where is the stomata located on a leaf
the epidermis
877570
and participatory plant breeding to find the best suited species such as heat and drought resistant crop varieties that could naturally evolve to the change in the face of food security challenges. Stoma In botany, a stoma (plural "stomata"), also called a stomata (plural "stomates") (from Greek στόμα, "mouth"), is a pore, found in the epidermis of leaves, stems, and other organs, that facilitates gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the stomatal opening. The term is usually used collectively to refer
Stoma
6280307
is used up and water leaves the guard cells, so they become flaccid and the stomatal pore closes. In this way, they reduce the amount of water vapour escaping from the leaf. The plant epidermis consists of three main cell types: pavement cells, guard cells and their subsidiary cells that surround the stomata and trichomes, otherwise known as leaf hairs. The epidermis of petals also form a variation of trichomes called conical cells. Trichomes develop at a distinct phase during leaf development, under the control of two major trichome specification genes: "TTG" and "GL1". The process may be controlled by
Epidermis (botany)
9903922
When a leaf is cleared with chloral hydrate and examined microscopically the oval stomata can be seen. They are surrounded by two crescent-shaped cells at right angles to the ostiole. The epidermis bears simple one- to three-celled warty hairs, and small glandular hairs. Cystoliths occur beneath the epidermis of the underside of the blade. The trunk has many, long, opposite, ascending branches, where the bark is yellowish in color. Flowers are usually white and the inflorescence shows large, dense, axillary spikes. Fruits are pubescent, and are with club-shaped capsules. The leaves of "Adhatoda vasica" contains phytochemicals such as alkaloids, tannins,
Justicia adhatoda
6280306
that lack chloroplasts. The stomata complex regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. Typically, the stomata are more numerous over the abaxial (lower) epidermis of the leaf than the (adaxial) upper epidermis. An exception is floating leaves where most or all stomata are on the upper surface. Vertical leaves, such as those of many grasses, often have roughly equal numbers of stomata on both surfaces. The stoma is bounded by two guard cells. The guard cells differ from the epidermal cells in the following aspects: At night, the sugar
Epidermis (botany)
877549
number of stomata on both leaf surfaces. In plants with floating leaves, stomata may be found only on the upper epidermis and submerged leaves may lack stomata entirely. Most tree species have stomata only on the lower leaf surface. Leaves with stomata on both the upper and lower leaf are called amphistomatous leaves; leaves with stomata only on the lower surface are hypostomatous, and leaves with stomata only on the upper surface are epistomatous or hyperstomatous. Size varies across species, with end-to-end lengths ranging from 10 to 80 µm and width ranging from a few to 50 µm. Carbon dioxide,
Stoma
3832867
the area of contact between the water droplet and the leaf. Ultrahydrophobicity is said to confer a very important evolutionary advantage. As an aquatic plant with leaves that rest on the water's surface, the genus "Nelumbo" is characterized by its concentration of stomata on the upper epidermis of its leaves, unlike most other plants which concentrate their stomata on the lower epidermis, underneath the leaf. The collection of water on the upper epidermis, whether that be by rain, mist, or the nearby disturbance of water, is very detrimental to the leaf's ability to perform gas exchange through its stomata. Thus,
Nelumbo
15687000
Stomatal conductance By definition, stomatal conductance, usually measured in mmol m⁻² s⁻¹, is the measure of the rate of passage of carbon dioxide (CO) entering, or water vapor exiting through the stomata of a leaf. Stomata are small pores on the top and or bottom of a leaf that are responsible for taking in and expelling CO and moisture from and to the outside air. The rate of stomatal conductance, or its inverse, stomatal resistance, is directly related to the boundary layer resistance of the leaf and the absolute concentration gradient of water vapor from the leaf to the atmosphere.
Stomatal conductance
12375503
complex. The opening and closing of the stomatal aperture is controlled by the stomatal complex and regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. Stomata therefore play the important role in allowing photosynthesis without letting the leaf dry out. In a typical leaf, the stomata are more numerous over the abaxial (lower) epidermis than the adaxial (upper) epidermis and are more numerous in plants from cooler climates. Most of the interior of the leaf between the upper and lower layers of epidermis is a "parenchyma" (ground tissue) or "chlorenchyma" tissue
Leaf
15687009
pressure deficit, formula_30 is the leaf-surface CO concentration, formula_31 is the CO compensation point. formula_32 and formula_33 are empirical coefficients. Stomatal conductance By definition, stomatal conductance, usually measured in mmol m⁻² s⁻¹, is the measure of the rate of passage of carbon dioxide (CO) entering, or water vapor exiting through the stomata of a leaf. Stomata are small pores on the top and or bottom of a leaf that are responsible for taking in and expelling CO and moisture from and to the outside air. The rate of stomatal conductance, or its inverse, stomatal resistance, is directly related to the
Stomatal conductance
8795685
leaf. The "Agrobacterium" suspension is then injected into the airspaces inside the leaf through stomata, or sometimes through a tiny incision made to the underside of the leaf. Vacuum infiltration is another way to introduce "Agrobacterium" deep into plant tissue. In this procedure, leaf disks, leaves, or whole plants are submerged in a beaker containing the solution, and the beaker is placed in a vacuum chamber. The vacuum is then applied, forcing air out of the intercellular spaces within the leaves via the stomata. When the vacuum is released, the pressure difference forces the "Agrobacterium" suspension into the leaves through
Agroinfiltration
14335934
Banksia novae-zelandiae Banksia novae-zelandiae is an extinct species of "Banksia", known only from fossil leaves found in the South Island of New Zealand. This species is based on several leaf fossils, all with triangular pinnate lobes cut all the way back to the midrib, and indistinct secondary venation. Stomata occur in areoles, and have very wrinkly subsidiary cells. Both leaf surfaces are covered in trichome bases, and the undersurface is covered in cuticular papillae. Fossil leaves were found at the Newvale Mine, Waimumu Coalfield, Southland District, South Island, New Zealand (), in a thin leaf litter bed located in a
Banksia novae-zelandiae
10985374
has been linked to the fall in the atmospheric carbon dioxide concentrations in the late Paleozoic era associated with a rise in density of stomata on leaf surface. This must have allowed for better transpiration rates and gas exchange. Large leaves with less stomata would have gotten heated up in the sun's heat, but an increased stomatal density allowed for a better-cooled leaf, thus making its spread feasible. Various physical and physiological forces like light intensity, humidity, temperature, wind speeds etc. are thought to have influenced evolution of leaf shape and size. It is observed that high trees rarely have
Plant evolutionary developmental biology
10550250
Abies numidica Abies numidica (Algerian fir) is a species of fir found only in Algeria, where it is endemic on Djebel Babor, the second-highest mountain (2,004 meters) in the Algerian Tell Atlas. "Abies numidica" is a medium-sized to large evergreen tree growing to 20–35 meters tall, with a trunk up to 1 meter diameter. The leaves are needle-like, moderately flattened, 1.5–2.5 centimeters long and 2–3 millimeters wide by 1 millimeters thick, glossy dark green with a patch of greenish-white stomata near the tip above, and with two greenish-white bands of stomata below. The tip of the leaf is variable, usually
Abies numidica
877550
a key reactant in photosynthesis, is present in the atmosphere at a concentration of about 400 ppm. Most plants require the stomata to be open during daytime. The air spaces in the leaf are saturated with water vapour, which exits the leaf through the stomata; this is known as transpiration. Therefore, plants cannot gain carbon dioxide without simultaneously losing water vapour. Ordinarily, carbon dioxide is fixed to ribulose-1,5-bisphosphate (RuBP) by the enzyme RuBisCO in mesophyll cells exposed directly to the air spaces inside the leaf. This exacerbates the transpiration problem for two reasons: first, RuBisCo has a relatively low affinity
Stoma
16868281
over guard cells and enter the leaf tissue through open stomata. Two germ tubes may even form from the same spore, the second protruding from the opposite end of the cell. This is the only known method of entry by "T.caerulescens", no direct penetration or appresoria have been observed in this species. Thus, infection occurs only on the underside of leaves, where stomata are found. In the saprophytic stage the single celled spores grow like yeast, that is to say they bud (replicate) directly. Spores may be disseminated by wind or rain. These cells then overwinter and serve as inoculum
Taphrina caerulescens
11500190
axil, sporangia are created from artificial cells. While stomata can be found following the leaf margin on the lower surface of the plant's leaves, stomata on the upper surface of "S. apoda" leaves disperse entirely following the laminae. The dorsal leaves of "S. apoda" have acuminate apices. The primary leaves of "S. apoda" significantly contrast in shape from the cotyledons of the plant. "Selaginella apoda" leaf blades have borders with a margin that is light green in appearance or simply identical to each other. The strobilus of "S. apoda" is often restricted to a length of 1-2 centimeters. Typically, the
Selaginella apoda
10788379
classification, "Memecylon" was placed in the Memecylaceae. Synapomorphies used in this phylogenetic analysis were anther connective and dehiscence, dorsal glands on stamen connectives, endothecium, placentation, locules, seeds, leaf venation, terminal leaf sclereids, paracytic stomata, stomata shape, leaf sclereids, indumentum, ant and mite domatia, wood and growth form characters, which excluded Memecylaceae from Melastomataceae. However, in "Memecylon" some characters such as seasonal flowering and small size of flowers contributed to the difficulty of assessing relationships based on the morphology. Later, several groups have been either included in broadly defined Memecylaceae or segregated from it. As a result, Memecylaceae comprised the groups
Memecylon
16001282
eventually infect new corn crop. In order for the pathogen to actually infect the host, high relative humidity and moisture (dew) on the leaves are necessary for inoculation. Primary inoculation occurs on lower regions of younger leaves, where conidia germinate across leaf surfaces and penetrate through stomata via a flattened hyphal organ, an appressorium. "Cercospora zeae-maydis" is atypical in that its conidia can grow and survive for days before penetration, unlike most spores that need to penetrate within hours to ensure survival. Once infection occurs, the conidia are produced in these lower leaf regions. Assuming favorable weather conditions (see Environment
Corn grey leaf spot
877565
However, dry climates are not the only places where they can be found. The following plants are examples of species with stomatal crypts or antechambers: "Nerium oleander", conifers, and "Drimys winteri" which is a species of plant found in the cloud forest. Stomata are obvious holes in the leaf by which, as was presumed for a while, pathogens can enter unchallenged. However, it has been recently shown that stomata do in fact sense the presence of some, if not all, pathogens. However, with the virulent bacteria applied to "Arabidopsis" plant leaves in the experiment, the bacteria released the chemical coronatine,
Stoma
2518866
benefit of CAM to the plant is the ability to leave most leaf stomata closed during the day. Plants employing CAM are most common in arid environments, where water comes at a premium. Being able to keep stomata closed during the hottest and driest part of the day reduces the loss of water through evapotranspiration, allowing such plants to grow in environments that would otherwise be far too dry. Plants using only carbon fixation, for example, lose 97% of the water they uptake through the roots to transpiration - a high cost avoided by plants able to employ CAM. The
Crassulacean acid metabolism
15102890
concentration increases. This is less tolerant to leakage and material ad/absorption. For CO to diffuse into the leaf, stomata must be open, which permits the outward diffusion of water vapour. Therefore, the conductance of stomata influences both photosynthetic rate (A) and transpiration (E), and the usefulness of measuring A is enhanced by the simultaneous measurement of E. The internal concentration (C) is also quantified, since C represents an indicator of the availability of the primary substrate (CO) for A. A carbon assimilation is determined by measuring the rate at which the leaf assimilates . The change in is calculated as
Photosynthesis system
10550275
Abies vejarii Abies vejarii is a species of fir native to northeastern Mexico, in the states of Coahuila and Nuevo León, where it grows at high altitudes (2,000–3,300 m) in the Sierra Madre Oriental. It is a medium-sized evergreen tree growing to 35–40 m tall. The leaves are needle-like, moderately flattened, 1–2.5 cm long and 1.3–2 mm wide by 1 mm thick, grey-green with scattered stomata above, and with two greenish-white bands of stomata below. The tip of the leaf is acutely pointed. The cones are glaucous purple, maturing grey-brown, 6–15 cm long and 4–6 cm broad, with about 150–200
Abies vejarii
10435953
mycelium protects the next generation of conidia and ensures survival through the winter via conidiophores, and the cycle starts again the next season. "Cercospora melongenae" overwinters in soil or plant debris as conidiophores which then can be dispersed to the plant by rain splash, irrigation water, wind or mechanical transport. The innoculum, conidia, enter through the stomata of the leaves where they germinate and produce more conidia on conidiophores. The conidia must have water or moisture in the form of heavy dew in order to germinate and therefore penetrate the leaf via. the stomata or other natural openings or wounds
Cercospora melongenae
1666305
by the processes of photosynthesis (see above) and transpiration. The latter process (which is responsible for about 90% of water use) is driven by the evaporation of water from the leaves of plants. Transpiration allows plants to transport water and mineral nutrients from the soil to growth regions, and also cools the plant. Diffusion of water vapour out of a leaf, the force that drives transpiration, is regulated by structures known as stomata. These structure also regulate the diffusion of carbon dioxide from the atmosphere into the leaf, such that decreasing water loss (by partially closing stomata) also decreases carbon
Primary production
12375479
controlling water loss. Their surfaces are waterproofed by the plant cuticle and gas exchange between the mesophyll cells and the atmosphere is controlled by minute (length and width measured in tens of µm) openings called stomata which open or close to regulate the rate exchange of carbon dioxide, oxygen, and water vapour into and out of the internal intercellular space system. Stomatal opening is controlled by the turgor pressure in a pair of guard cells that surround the stomatal aperture. In any square centimeter of a plant leaf there may be from 1,000 to 100,000 stomata. The shape and structure
Leaf
771635
unique stomata and isotopic profile give it a key role in recreations of the Mesozoic and Cenozoic. Leaf fossils that resemble the "Ginkgophytes" are known as "Ginkgoites". There are similar, now extinct, morphogens, such as "Sphenobaiera", which describes fan-shaped, deeply divided leaves without clear petioles. The distinctive shape of the modern "Ginkgo biloba" gives the impression of a very narrow leaf morphology, but the group is varied and diverse. The genus "Ginkgo" by itself contains a range of morphologies. "Ginkgo digitata", from the Jurassic, has long, wedge-shaped laminae with the intercostal regions covered in stomata and resin bodies, while "G.
Ginkgoales
12366073
of transpiration is governed by the number of stomata, stomatal aperture i.e. the size of the stoma opening, leaf area (allowing for more stomata), temperature differential, the relative humidity, the presence of wind or air movement, the light intensity, and the presence of a waxy cuticle. It is important to note, that whilst it is vital to keep stomata closed, they have to be opened for gaseous exchange in respiration and photosynthesis. Xerophytic plants may have similar shapes, forms, and structures and look very similar, even if the plants are not very closely related, through a process called convergent evolution.
Xerophyte
4185190
hours and moderate temperatures of 60 to 80 °F (15.6 to 26.7 °C). The Process: The infection process starts when urediniospores germinate to produce a single germ tube that grows across the leaf surface, until an appressorium forms. Appressoria form over anticlinal walls or over the center of epidermal cells, but rarely over stomata. Penetration of epidermal cells is by direct penetration through the cuticle by an appressorial peg. When appressoria form over stomata, the hyphae penetrate one of the guard cells rather than entering the leaf through the stomatal opening. This rust and related species are unique in their
Soybean rust
19277883
absorption of the ground are unfavourable either physically or physiologically. Examples of such structures are: (1) covering of wax, (2) thick cuticle, (3) sub-epidermal protective tissue, (4) water tissue, (5) covering of hairs (6) covering of the stomata, (7) sinking of the stomata, (8) inclusion of the stomata in a space protected from air currents, (9) diminution of the evaporating surface, &c. The matter however is so complicated that it is very difficult to reach an exact appraisal of these adaptations in characterizing the individual plant communities biologically. ... In general we must content ourselves with showing the most frequently
Leaf size
10203018
to disperse. A nitrogen-deficient plant as well as a plant with excess nitrogen favors disease prevalence, making well-timed fertilizer applications important. Other factors that can increase disease incidence are insufficient shade, herbicide injury, plant stress, and other diseases caused by nematodes. The reason for increased disease is that stressed plants are more susceptible. Conidia of "Mycosphaerella coffeicola" are produced year-round and enter the coffee plant through stomata on the underside of a leaf, or through the epidermal cuticle on the upper leaf surface. Inter- and intracellular hyphal growth creates vegetative lesions where sporulation occurs. Conidiophores and conidia are formed here,
Mycosphaerella coffeicola
14998088
cotyledons may develop blackened margins, shrivel, and drop. The bacteria progress through the vascular system to the young stems and leaves, where the disease manifests as V-shaped chlorotic to necrotic lesions extending from the leaf margins. Under humid conditions, bacteria present in guttation droplets can be spread by wind, rain, water splashes, and mechanical equipment to neighboring plants. The natural route of invasion by Xcc is through the hydathodes, though leaf wounds caused by insects and plant roots may also be portals of entry. Occasionally, infections occur through stomata. Hydathodes provide the pathogen a direct path from the leaf margins
Xanthomonas campestris pv. campestris
10162277
after the simple leafless plants had colonized the land in the Early Devonian. This spread has been linked to the fall in the atmospheric carbon dioxide concentrations in the Late Paleozoic era associated with a rise in density of stomata on leaf surface. This would have resulted in greater transpiration rates and gas exchange, but especially at high concentrations, large leaves with fewer stomata would have heated to lethal temperatures in full sunlight. Increasing the stomatal density allowed for a better-cooled leaf, thus making its spread feasible, but increased CO2 uptake at the expense of decreased water use efficiency. The
Evolutionary history of plants
18444781
bacterial leaf streak will exhibit an orange cast from leaf symptoms and suffer yield and quality loss. Bacterial leaf streak of wheat is a seed-borne disease and is primarily transported by seed, but can also be transmitted by plant-to-plant contact within its lifecycle. Epidemics are typically observed late in the growing season and in wet environments. Moisture facilitates the release of the pathogen from the inoculated seed, which leads to leaf colonization and invasion of tissue. Bacteria on the moist leaf surface enter through leaf openings, such as the stomata or wounds. Under moderately warm weather conditions (15-30 degrees Celsius)
Bacterial leaf streak
16853504
leaf or enter through a natural opening such as the stomata. The parenchymatous leaf tissue is invaded by the mycelium of the fungus; cells of the leaf tissue subsequently begin to turn brown and collapse. These lesions give rise to conidiophores which, upon favorable conditions, can either further infect the original host plant (kernels, husks, stalks, leaves) or release conidia to infect other nearby plants. The term 'favorable conditions' implies that water is present on the leaf surface and temperature of the environment is between 60 and 80 degrees Fahrenheit. Under these conditions, spores germinate and penetrate the plant in
Southern corn leaf blight
6280311
asymmetrically to form the subsidiary cells. Because stomata play such an important role in the plants survival, collecting information on their differentiation is difficult by the traditional means of genetic manipulation, as stomatal mutants tend to be unable to survive. Thus the control of the process is not well understood. Some genes have been identified. "TMM" is thought to control the timing of stomatal initiation specification and "FLP" is thought to be involved in preventing further division of the guard cells once they are formed. Environmental conditions affect the development of stomata, in particular their density on the leaf surface.
Epidermis (botany)
12366655
Transpiration Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth and metabolism. The remaining 97–99.5% is lost by transpiration and guttation. Leaf surfaces are dotted with pores called stomata, and in most plants they are more numerous on the undersides of the foliage. The stomata are bordered by guard cells and their stomatal accessory cells (together known as stomatal complex) that open and close the pore.
Transpiration
19428801
rare character. Leaf stems have narrow wings on each side, which is a continuation of the leaf blades. Blades are about 12 cm long and 4–5 cm wide, leathery with a rounded tip, have a foot that gradually narrows into the wings of the leaf stem, and have widely spaced teeth along the margins, particularly in the distal half. These teeth are clear to see in leaves on young shoots but become very subtle on leaves on older growth. The tip of the teeth is opaque. The stomata are restricted to the underside (or abaxial surface), and are of the
Strasburgeria
10435952
and open stomata. Multiple germ tubes from various conidia can enter the same stomata. This fungus has the best infection rates among young leaves and has a reduced infection rate of mature leaves. It is thought that the reduced infection rate of mature leaves is due to the saprophytic microflora on the leaves and the anti-fungal compounds produced by the mature leaf. This fungus produces secondary conidia within the same season; this furthers the disease cycle and allows the fungus to infect more plants. Mycelium rapidly develops. Under near perfect conditions, mycelium can develop within twelve hours of infection. The
Cercospora melongenae
19560968
Leaf expansion Leaf expansion is a process by which plants make efficient use of the space around them by causing their leaves to enlarge, or wither. This process enables a plant to maximize its own biomass, whether it be due to increased surface area; which enables more sunlight to be absorbed by chloroplasts, driving the rate of photosynthesis upward, or it enables more stomata to be created on the leaf surface, allowing the plant to increase its carbon dioxide intake. Initially, sensory organs, such as chloroplasts, the cambium, and roots, detect an external stimuli, such as light. The stimulus triggers
Leaf expansion
10391043
to a point at the end. Their outline is falcate, or sickle-like, to more or less straight and flat. The texture is somewhat leathery, but generally they are quite soft and flexible. The midvein is 0.2 to 0.5 mm wide on the abaxial surface, or underside, showing two broad and grey stomatal bands that are 0.8 to 2.1 mm wide with 13 to 24 rows of stomata, though the individual stomata are not readily visible to the naked eye. The leaf base is cuneate, or wedge-shaped, to shortly attenuate, while the apex is cuspidate, or fine pointed. The cusp, or
Cephalotaxus fortunei
5419693
susceptible hosts. The bacteria infect new plants through stomata and wounds. The wound can be caused by pruning or hedging that could cut open mesophyll tissues for direct infection. The rain can also cause water congestion on leaf surface, form column of water through stomata and promote infection through the natural opening. The infection can form on fruit, foliage and young stem. Leaves and stems are most susceptible to infection within the first six weeks of initial growth. Infection of fruit is most likely to occur during the 90 day period after petal fall during fruit formation. The varied size
Citrus canker
877564
1889, was further developed by Metcalfe and Chalk, and later complemented by other authors. It is based on the size, shape and arrangement of the subsidiary cells that surround the two guard cells. They distinguish for dicots: In monocots, several different types of stomata occur such as: In ferns, four different types are distinguished: Stomatal crypts are sunken areas of the leaf epidermis which form a chamber-like structure that contains one or more stomata and sometimes trichomes or accumulations of wax. Stomatal crypts can be an adaption to drought and dry climate conditions when the stomatal crypts are very pronounced.
Stoma
10550810
the shoot and down on the other side. The leaf blades are usually 15-25 millimeters long, 3-5 millimeters wide and ovate-lanceolate or ovate-elliptic in shape. Juvenile leaves are often larger. The narrow midrib of the leaf is conspicuous on the abaxial side. Stomata are present on both sides of the leaf. "Retrophyllum vitiense" is dioecious. The cylindrical male pollen cones are borne apically on short lateral or subterminal branchlets. They grow in groups of two or three. A pollen cone consists of numerous spirally arranged microsporophylls around a 10-25 millimeter long rachis. The microsporophylls are triangular and keeled, bearing two
Retrophyllum vitiense
9211874
and the rough upper leaf surface, which contains the gas exchange openings (stomata), can orient itself away from wind. Beachgrass is a dominant species on foredunes, and indeed is sometimes the only plant found there. It is much less vigorous further in from the coastline, which is puzzling. Why should a species that competes so well on foredunes be fairly unsuccessful just a few meters further in from the coast, where other plants usually dominate? One mechanism for this effect that has been extensively studied by Wim van der Putten and his colleagues is based on the susceptibility of "Ammophila"
Ammophila breviligulata
10102537
air currents, and their release from the lesions can be triggered by rainfall, or even just a sudden drop in humidity. When the conidium lands on a leaf, it will wait until the nighttime dew, and then germinate. It can either enter through the stomata, or penetrate directly through the top of the leaf, using its appressorium, infecting the leaf within 12 hours. At the cellular level, toxins are produced by AAL that are essential for pathogenicity on tomato. This host specific mycotoxin is called fumonisin B It was identified and confirmed by research conducted on fast atom bombardment and
Alternaria alternata
4206522
in the Pacific Northwest. "Abies grandis" is a large evergreen coniferous tree growing to 40–70 m (exceptionally 100 m) tall and with a trunk diameter of up to 2 m. The leaves are needle-like, flattened, 3–6 cm long and 2 mm wide by 0.5 mm thick, glossy dark green above, and with two green-white bands of stomata below, and slightly notched at the tip. The leaf arrangement is spiral on the shoot, but with each leaf variably twisted at the base so they all lie in two more-or-less flat ranks on either side of the shoot. On the lower leaf
Abies grandis
17626657
overwinters in dead leaves on the ground. In early spring (about petal fall), fungal fruiting bodies called apothecia develop in these leaves. Spores (ascospores) are produced in the apothecia and are forcibly discharged starting at petal fall. These ascospores are spread by wind or rain to the healthy, new, green leaves and thus serve as the primary inoculum in a new growing season. The ascospores can stick to the leaf and if a film of water and optimal temperature is present, germinate within hours of adhesion. Upon germination, the ascospores can enter the leaf through the stomata (natural openings) on
Cherry leaf spot
14788208
being able to escape diseases. Plant physiologists have investigated how the leaves of the tree differ depending on their location in the forest canopy finding they are thicker in the canopy and thinner in the understory. They have also measured how the water potential of their leaves changes and when their stomata open and close during the day; the findings suggest that rather than closing their stomata to control water loss, it is controlled by the leaf area instead. Population geneticists have examined the way in which its genes vary, at both the local scale and across its range using
Simarouba amara
8381498
de Navidad" (Christmas tree) in Mexico. The English name derives from the binomial "Abies religiosa", literally "religious fir". This comes from the use of its cut foliage in religious festivals in Mexico, notably at Christmas. "Abies religiosa" is a medium-sized to large evergreen coniferous tree growing to tall with a trunk diameter of up to . The leaves are needle-like, flattened, long and wide by thick, dark green above, and with two blue-white bands of stomata below; the leaf apex is acute. The leaf arrangement is spiral on the shoot, but with each leaf variably twisted at the base so
Abies religiosa
759263
ribosomes, but cells next to them, the companion cells, function to keep the sieve-tube members alive. The most abundant compound in all plants, as in all cellular organisms, is water which serves an important structural role and a vital role in plant metabolism. Transpiration is the main process of water movement within plant tissues. Water is constantly transpired from the plant through its stomata to the atmosphere and replaced by soil water taken up by the roots. The movement of water out of the leaf stomata creates a transpiration pull or tension in the water column in the xylem vessels
Vascular plant
18726956
Bryan Barlow in Nuytsia as a new species. The specific epithet ("pomphostoma") is from the Ancient Greek words "pomphos" meaning "a blister" and "stoma" meaning "mouth" referring to the raised stomata on the lower leaf surface. This melaleuca is confined to the Ravensthorpe district and the eastern end of the Fitzgerald River National Park in the Esperance Plains biogeographic region where it usually grows in sand or clayey loam "Melaleuca pomphostoma" is classified as "not threatened" by the Government of Western Australia Department of Parks and Wildlife. Melaleuca pomphostoma Melaleuca pomphostoma is a plant in the myrtle family, Myrtaceae, and
Melaleuca pomphostoma
2339374
lower surface of the leaf. Gases enter into the photosynthetic tissue of the leaf through dissolution onto the moist surface of the palisade and spongy mesophyll cells. The spongy mesophyll cells are loosely packed, allowing for an increased surface area, and subsequently an increased rate of gas-exchange. Uptake of carbon dioxide necessarily results in some loss of water vapor, because both molecules enter and leave by the same stomata, so plants experience a gas exchange dilemma: gaining enough without losing too much water. Therefore, water loss from other parts of the leaf is minimised by the waxy cuticle on the
Gas exchange
4975916
20–38 μm long and 15–25 μm wide are restricted to the underside of the leaf. Leaf shape, size and shape of the stomata and epidermal cells, the presence of non-glandular hairs, and of stalked glands that strongly differ in size on the lower leaf surface and on the margins including a terminal tentacle, as well as the head of the tentacle having an apical pore, are all characters shared with extant "Roridula" species. These fossils differ from today's dewsticks in having smaller tentacles, and in lacking a prominent midrib on the underside of the leaf. The pieces of amber with
Roridula
17758119
in an environment with much more than it otherwise would be, it performs more efficiently. A second mechanism, CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions. The most important benefit of CAM to the plant is the ability to leave most leaf stomata closed during the day. This reduces water loss due to evapotranspiration. The stomata open at night to collect , which is stored as the four-carbon acid malate, and then used during photosynthesis during the day. The pre-collected is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency. More
Evolution of photosynthesis
16450582
in plant debris and soil during unfavourable conditions. Many publications report "Phoma clematidina" to be a wound pathogen. However, although wounding may aid infection, scientific trials have shown that, in susceptible "Clematis" varieties, the fungus can cause extensive leaf spotting and wilt without any previous damage to plant tissues. When spores of "Phoma clematidina" land on a leaf of a susceptible plant under the right environmental conditions (moisture, temperature 15 to 25 °C), they will germinate within 6 hours and infect leaf tissues directly or via leaf hairs (but never via stomata). Initial symptoms are small brown lesions which then
Phoma clematidina
18442098
dried leaf. Spores germinate in the leaf surface with free water and humidity with above 85%. This pathogen can survive at least one year without a host which is called non-obligate. The temperature must be between 40°~94 °F (4°~34 °C) for germinating spore. The pathogen usually infects the leaves by penetrating through stomata in a high humidity level. The life cycle starts with the fungus overwintering as sclerotia on plants debris, in seeds and in soils as a saprophyte. Conidia also play an important role as survival structure, once that it are resistant to drying, and might survive up to
Tomato leaf mold
10308004
Plasmopara viticola Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet condition release zoospores. Zoospores are splashed by rain into the canopy, where they swim to and infect through stomata. After 7–10 days, yellow lesions appear on foliage. During favorable weather, the lesions sporulate and new secondary infections occur. "Plasmopara viticola", also known as grape downy mildew, is considered to be the most devastating disease of grapevines in climates with relatively warm and humid summers. It
Plasmopara viticola
7005296
altitudes of up to 1,800 m ASL. The flowers are usually colored in orange hues and often spotted, but background colors also include shades white, yellow and red. They are born in axillary cymes without bracteoles. "Gasteranthus" was previously included in the closely related genus "Besleria". The two genera have been separated on the basis of differences in their stomata (aggregated in "Gasteranthus", scattered in "Besleria") and fruits (fleshy capsule in "Gasteranthus", berry in "Besleria"). Characteristic are the whitish dots on the leaf undersides caused by aggregations of stomata in "Gasteranthus". Two main groups can be distinguished in this genus:
Gasteranthus
6000698
horizontal plane around the shoot. The leaf petioles in "Retrophyllum" are uniquely twisted on the lateral shoots in opposite directions on each side of a shoot orienting the leaf blades with the adaxial or ventral surface upwards on one side of the shoot and the abaxial or dorsal surface upwards on the opposite side of the shoot. The leaf blade varies in shape from lanceolate to narrowly ovate. The leaves have conspicuous midribs and are amphistomatic with stomata present on both sides. "Retrophyllum" are dioecious with male pollen cones and female seed cones on separate individual trees. The male pollen
Retrophyllum
13790597
Red thread disease Red thread disease is a fungal infection found on lawns and other turfed areas. It is caused by the corticioid fungus "Laetisaria fuciformis" and has two separate stages. The stage that gives the infection its name is characterised by very thin, red, needle-like strands extending from the grass blade. These are stromata, which can remain viable in soil for two years. After germinating, the stromata infect grass leaf blades through their stomata. The other stage is visible as small, pink, cotton wool-like mycelium, found where the blades meet. It is common when both warmth and humidity are
Red thread disease
10308017
European cultivars such as Regent have been developed from progeny of crosses between "V.vinifera" and resistant North American species in an effort to incorporate the most desirable qualities of both parental branches. Plasmopara viticola Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet condition release zoospores. Zoospores are splashed by rain into the canopy, where they swim to and infect through stomata. After 7–10 days, yellow lesions appear on foliage. During favorable weather, the lesions sporulate
Plasmopara viticola
1353256
grass has a rolled leaf that creates a localized environment of water vapour concentration within the leaf, and helps to prevent water loss. The stomata sit in small pits within the curls of the structure, which make them less likely to open and to lose water. The folded leaves have hairs on the inside to slow or stop air movement, much like many other xerophytes (though these are typically found on the outside of the plant, but in marram grass they are also within the leaf as this has now become a structure with more volume). This slowing of air
Ammophila (plant)
12365976
of water shortage. Succulent plants such as the cacti store water in the vacuoles of large parenchyma tissues. Other plants have leaf modifications to reduce water loss, such as needle-shaped leaves, sunken stomata, and thick, waxy cuticles as in the pine. The sand-dune marram grass has rolled leaves with stomata on the inner surface. Hydrophytes are plants in water habitats. They mostly grow in water or in wet or damp places. In these plants the water absorption occur through the whole surface of the plant, e.g., the water lily. Halophytes are plants living in marshy areas (close to sea). They
Osmoregulation
2121609
is fixed instead of carbon. This phenomenon is primarily temperature-dependent. High temperature decreases the concentration of dissolved in the moisture in the leaf tissues. This phenomenon is also related to water stress. Since plant leaves are evaporatively cooled, limited water causes high leaf temperatures. plants use the enzyme PEP carboxylase initially, which has a higher affinity for . The process first makes a 4-carbon intermediate compound, which is shuttled into a site of photosynthesis then de-carboxylated, releasing to boost the concentration of , hence the name plants. Crassulacean acid metabolism (CAM) plants keep their stomata (on the underside of the
RuBisCO
877557
in the closing of the stomatal pores. Guard cells have more chloroplasts than the other epidermal cells from which guard cells are derived. Their function is controversial. The degree of stomatal resistance can be determined by measuring leaf gas exchange of a leaf. The transpiration rate is dependent on the diffusion resistance provided by the stomatal pores, and also on the humidity gradient between the leaf's internal air spaces and the outside air. Stomatal resistance (or its inverse, stomatal conductance) can therefore be calculated from the transpiration rate and humidity gradient. This allows scientists to investigate how stomata respond to
Stoma
7031424
recognizable midrib. The nerves spring directly from the edge of the leaf rhachis and then run towards the plumage axis. The spars are hairy at least on young leaves. The hairs (trichomes) are colorless, branched or simple. The stomata for the gas exchange are found either only on the underside of the leaf, or in some species on both sides. Glands are not otherwise colored and difficult to identify. The cells of the leaf epidermis are extended parallel to the plumage axis. Like other cycads, coral-like roots are sometimes formed that grow up from the primary root and branch out
Dioon
3365718
emerging through stomata in the streak that has developed. Further epiphytic growth occurs before the re-entry of the hypha into the leaf through another stoma repeats the process. The optimal conditions for "M. fijiensis" as compared with "M. musicola" are a higher temperatures and higher relative humidity, and the whole disease cycle is much faster in "M. fijiensis". Black Sigatoka is also known as Black Leaf Streak, and is found mostly on the banana crop. The pathogen "Mycosphaerella fijiensis" causes streaks that run parallel to the leaves. It is an ascomycete fungus that affects banana trees specifically in tropical climates;
Black sigatoka
18726955
to 12 individual flowers, the spike about wide. They are greenish-yellow with the stamens arranged in five bundles around each flower, the bundles containing 11 to 18 stamens. The flowering season is in autumn and winter and is followed by fruit which are woody capsules long. "Melaleuca pomphostoma" is similar to "Melaleuca bracteosa" but differs from it in having fewer stamens ("M. bracteosa" has 7 to 11 per bundle), a different leaf shape and distinctive, numerous, white raised stomata, which are barely visible with a hand lens, on the leaf blades. "Melaleuca pomphostoma" was first formally described in 1992 by
Melaleuca pomphostoma
10550806
adaxial sides of the leaves face up on one side of the shoot and down on the other side. The leaf blades are most commonly 10-18 millimeters long and 3-5 millimeters wide. They are ovate-lanceolate or ovate-elliptic in shape with visible midribs and entire margins. Stomata can be found on both surfaces of the leaf. The species is dioecious. The male pollen cones are 5-7 millimeters long with spirally arranged triangular sporophylls. The female seed cones each have a single subterminal fertile cone scale with a single ovule developing into a seed. The seed is covered by a fleshy epimatium.
Retrophyllum rospigliosii
6103075
commonly found at and immediately below the tree line. It is a medium-sized tree growing to tall, exceptionally to tall, with a trunk up to across, and a very narrow conic crown. The bark on young trees is smooth, gray, and with resin blisters, becoming rough and fissured or scaly on old trees. The leaves are flat and needle-like, long, glaucous green above with a broad stripe of stomata, and two blue-white stomatal bands below; the fresh leaf scars are reddish. They are arranged spirally on the shoot, but with the leaf bases twisted to be arranged to the sides
Abies lasiocarpa
8834309
by concentrating within their leaves using carbon fixation or Crassulacean acid metabolism. However, most species used carbon fixation and must open their stomata to take in whenever photosynthesis is taking place. Wind has three very different effects on plants. Wind influences the way leaves regulate moisture, heat, and carbon dioxide. When no wind is present, a layer of still air builds up around each leaf. This is known as the boundary layer and in effect insulates the leaf from the environment, providing an atmosphere rich in moisture and less prone to convective heating or cooling. As wind speed increases, the
Ecophysiology
10425462
about five days before penetrating the leaf via a stoma. Once inside the leaf the invasive hypha forms a vesicle and fine hyphae grow through the mesophyll layers into an air chamber. More hyphae then grow into the palisade tissue and continue on into other air chambers, eventually emerging through stomata in the streak that has developed. Further epiphytic growth occurs before the re-entry of the hypha into the leaf through another stoma repeats the process. Both conidia and ascospores are important for dispersal of M. musicola with the ascospores being involved in the movement of the pathogen over longer
Mycosphaerella musicola
12366659
stomata into the atmosphere. Water is absorbed at the roots by osmosis, and any dissolved mineral nutrients travel with it through the xylem. The cohesion-tension theory explains how leaves pull water through the xylem. Water molecules stick together, or exhibit cohesion. As a water molecule evaporates from the surface of the leaf, it pulls on the adjacent water molecule, creating a continuous flow of water through the plant. Plants regulate the rate of transpiration by controlling the size of the stomatal apertures. The rate of transpiration is also influenced by the evaporative demand of the atmosphere surrounding the leaf such
Transpiration
18442099
one year in the absence of a susceptible host. When the condition are favorable the sclerotia produce new conidia, which act as primary inoculum to infect plants. The conidia produce mycelium that infects the plant through stomata when humidity is 85% or higher and produce conidiophores on the abaxial leaf surface of infected leaves. The symptoms usually start to appear 10 days after inoculation with spore formation, a large number of conidia are produced and these spores are easily spread from plant to plant by the wind, splash water, on tools, clothing of workers and also by insects. Spores are
Tomato leaf mold
8703288
pinnate with a single strand ("nerve") of vascular tissue. As in most ferns, young fronds have circinate vernation. In most species, the frond, apart from the vascular tissue, is only a single cell thick, and they do not have any stomata. The cuticle is also greatly reduced or absent, leaving filmy ferns very susceptible to desiccation where a reliable water supply is not present. The leaves occasionally bear hairs, but scales are generally not present. The sori are borne at the leaf margins at the end of the nerve. They are protected by conical, bivalvate, or tubular indusia. Within the
Hymenophyllaceae
3670968
may be sessile or short petiolate. The phyllotaxis or leaf arrangement is spiral and may be subopposite on some shoots. The leaves are usually linear-lanceolate or linear-elliptic in shape, though they can be broader lanceolate, ovate or nearly elliptic in some species. Juvenile leaves are often larger than adult leaves though similar in shape. The leaves are coriaceous and have a distinct midrib. The stomata are usually restricted to the abaxial or underside of the leaf, forming two stomatal bands around the midrib. "Podocarpus" are generally dioecious, with the male pollen cones and female seed cones borne on separate individual
Podocarpus
79125
plants such as cacti, chloroplasts are found in the stems, though in most plants, chloroplasts are concentrated in the leaves. One square millimeter of leaf tissue can contain half a million chloroplasts. Within a leaf, chloroplasts are mainly found in the mesophyll layers of a leaf, and the guard cells of stomata. Palisade mesophyll cells can contain 30–70 chloroplasts per cell, while stomatal guard cells contain only around 8–15 per cell, as well as much less chlorophyll. Chloroplasts can also be found in the bundle sheath cells of a leaf, especially in C plants, which carry out the Calvin cycle
Chloroplast
18251169
below the surface of the soil. The absence of stomata in the translucent tissue of the window prevents water loss in the plant. This allows succulents to minimize the exposure of leaf surface area to the outside environment and reduce the risk of desiccation under intense heat. The actual green, photosynthesizing surface is hidden in the underground part of the plant, so that it collects only the diffused light that strikes the windows, which in turn focusses and channels it to the leaves' inside surface. Experiments in the Lithops species of succulents, have shown that the size of leaf windows
Leaf window
17626658
the underside of the leaf. Ascospores cannot enter immature stomata very effectively. These ascospores grow in the intercellular spaces in the leaf. Incubation time will vary depending on the amount of available moisture and temperatures. The small purple lesions can appear within 5 days if there are damp conditions and the temperature remains steady between . This incubation period could take as long as 15 days though if lower temperatures and drier conditions occur. Generally leaves become less susceptible to the disease as they grow older during the course of the growing season. The first sign of disease may be
Cherry leaf spot
7173430
are shaded in parking lots, evaporative emissions from fuel and volatilized plastics will be greatly reduced. The volatile components of asphalt pavement evaporate more slowly in shaded parking lots and streets. The shade not only reduces emissions, but reduces shrinking and cracking so that maintenance intervals can be lengthened. Less maintenance means less hot asphalt (fumes) and less heavy equipment (exhaust). The same principle applies to asphalt-based roofing. Trees also reduce pollution by actively removing it from the atmosphere. Leaf stomata, the pores on the leaf surface, take in polluting gases which are then absorbed by water inside the leaf.
Urban forest
3680057
toward the ends. Stomata may be found on either both surfaces of the leaf or only the abaxial or underside. The leaf surface is coriaceous. "Nageia" are generally dioecious, with male pollen cones and female seed cones borne on separate individual plants but may sometimes be monoecious. The cones are pedunculate and develop from axillary buds. The pollen cones are long and ovoid-cylindric in shape. They may be solitary or grow in small spicate groups of two to six cones. Each pollen cone has numerous spirally inserted microsporophylls. The microsprophylls may be triangular or apiculate in shape. Each of them
Nageia
4975915
and a thick, hoof-shaped or egg-shaped head, with a small pore at its very tip. The stalks are 20–350 μm long (one stalk reaching 1.4 mm), the heads 20–120 μm long and 10–40 μm wide. Organic remains and hairs of other plant species are positioned on the heads, suggesting these were sticking to a secretion from the heads. The surface of the leaf consists of small six-sided cells at the base of the leaf and long, larger cells from the center to the tip of the leaf. These epidermal cells are 3–54 μm long and 6–18 μm wide. Stomata of
Roridula
772375
opposite pairs or whorls of 3 (−4). In many species with spirally arranged leaves, such as "Abies grandis" (pictured), the leaf bases are twisted to present the leaves in a very flat plane for maximum light capture. Leaf size varies from 2 mm in many scale-leaved species, up to 400 mm long in the needles of some pines (e.g. Apache Pine, "Pinus engelmannii"). The stomata are in lines or patches on the leaves, and can be closed when it is very dry or cold. The leaves are often dark green in colour, which may help absorb a maximum of energy
Pinophyta
10297546
sexual and an asexual stage. The asexual stage of this pathogen was first found in 1902, while the sexual stage was later discovered in 1942. The asexual stage produces conidiophores with conidia, and the sexual stage is an ascus with ascospores - produced by meiosis. Starting with the primary inoculum, the spores get disseminated by the wind. These spores go and infect the leaves by penetration through wounds or stomata penetration. Inter- and intracellular hyphae then infect into the leaf and a conidiophore tuft gets formed on the lower leaf surface. These conidiophore tufts produce conidia which are the second
Mycosphaerella angulata
15739025
that are thick and fleshy. These rhizomes are hard to pry since they are submerged in mud and are difficult to dig. The leaves float on the water surface, and have an external waxy coating which makes the leaf waterproof and thus allows the leaf stomata to breathe freely; they are glossy green, oval, 10–45 cm long and 7–30 cm wide, with a notch at one side to the leaf stem. The leaves provide shelter for fish. The rhizomes (underground stems) are round and submerged in mud. The flowers are 5–10 cm diameter, and have 6 to 12 (most often
Nuphar polysepala
2711321
increased by: Factors which influence this include the atmospheric abundance of the two gases, the supply of the gases to the site of fixation (i.e. in land plants: whether the stomata are open or closed), the length of the liquid phase (how far these gases have to diffuse through water in order to reach the reaction site). For example, when the stomata are closed to prevent water loss during drought: this limits the supply, while production within the leaf will continue. In algae (and plants which photosynthesise underwater); gases have to diffuse significant distances through water, which results in a
Photorespiration
6917315
causing a closure in stomata as to reduce the amount of carbon dioxide assimilation. Closing of the stomata also slows the rate of transpiration, which limits water loss and helps to prevent the wilting effects of moisture stress. This closing can be trigged by the roots sensing dry soil and in response producing the hormone ABA which when transported up the xylem into the leaves will reduce stomatal conductance and wall extensibility of growing cells. This lowers the rates of transpiration, photosynthesis and leaf expansion. ABA also increases the loosening of growing root cell walls and in turn increases root
Moisture stress
14335939
dispersal of seeds across thousands of kilometers of ocean. Banksia novae-zelandiae Banksia novae-zelandiae is an extinct species of "Banksia", known only from fossil leaves found in the South Island of New Zealand. This species is based on several leaf fossils, all with triangular pinnate lobes cut all the way back to the midrib, and indistinct secondary venation. Stomata occur in areoles, and have very wrinkly subsidiary cells. Both leaf surfaces are covered in trichome bases, and the undersurface is covered in cuticular papillae. Fossil leaves were found at the Newvale Mine, Waimumu Coalfield, Southland District, South Island, New Zealand (),
Banksia novae-zelandiae
2105803
stomata, where they can also be affected and destroyed by pressure similar to what can damage to stomatal tissue. Evidently, in both conifers and Lepidodendroids, the parichnoi, as the primary lenticular structure, appear as paired structures on either side of leaf scars. The development and increase in the number of these primitive lenticels were key to providing a system that was open for aeration and gas exchange in these plants. In plant bodies that produce secondary growth, lenticels promote gas exchange of oxygen, carbon dioxide, and water vapor. Lenticel formation usually begins beneath stomatal complexes during primary growth preceding the
Lenticel
16209070
revolute leaf margins are very likely an adaption to the harsh growing conditions of its range, presumably adding structural integrity to leaves often exposed to frost, sleet and driving wind, as well as very high UV levels. The margins would also reduce air movement across the stomata, presumably protecting the plant from desiccation. This is supported by observations that plants growing in shady subalpine pockets—where the need for sunlight may offset the need for a tough exterior—tend to have flatter or broader leaves with recurved rather than revolute margins. Little is known about fungal interactions with "O. revolutus", however there
Orites revolutus
15102883
Photosynthesis system Photosynthesis systems are electronic scientific instruments designed for non-destructive measurement of photosynthetic rates in the field. Photosynthesis systems are commonly used in agronomic and environmental research, as well as studies of the global carbon cycle. Photosynthesis systems function by measuring gas exchange of leaves. Atmospheric carbon dioxide is taken up by leaves in the process of photosynthesis, where is used to generate sugars in a molecular pathway known as the Calvin cycle. This draw-down of induces more atmospheric to diffuse through stomata into the air spaces of the leaf. While stoma are open, water vapor can easily diffuse
Photosynthesis system
16168829
many physiological factors, which makes it a powerful. (b) Stomatal conductance Canopy temperature depression is highly suitable for selecting physiologically superior lines in warm, low relative humidity environments where high evaporative demand leads to leaf cooling of up to 10 °C below ambient temperatures. This permits differences among genotypes to be detected relatively easily using infrared thermometry. However, such differences cannot be detected in high relative humidity environments because the effect of evaporative cooling of leaves is negligible. Nonetheless, leaves maintain their stomata open to permit the uptake of CO2, and differences in the rate of CO2 fixation may lead
Breeding for heat stress tolerance
6691083
two broad, vividly white bands of stomata below, and slightly notched at the tip. The leaf arrangement is spiral on the shoot, but with each leaf variably twisted at the base so they lie mostly either side of and above the shoot, with fewer below the shoot. The shoots are green-grey at first, maturing pinkish-grey, with scattered fine pubescence. The cones are long and broad, dark purple-blue before maturity; the scale bracts are long, green or yellow, and emerge between the scales in the closed cone. The winged seeds are released when the cones disintegrate at maturity about 5–6 months
Abies koreana
6120446
by 0.5 mm thick, matt dark green above, and with two white bands of stomata below, and slightly notched at the tip. The leaf arrangement is spiral on the shoot, but with each leaf variably twisted at the base so they lie flat to either side of and above the shoot, with none below the shoot. The shoots are orange-red with dense velvety pubescence. The cones are 5–11 cm long and 3–4 cm broad, dark purple-blue before maturity; the scale bracts are short, and hidden in the closed cone. The winged seeds are released when the cones disintegrate at maturity
Abies mariesii
46207
be seated or have a leafstalk. The leaf blade is usually simple, entire or dissected, rarely trifoliolate or pinnately compound. A leaf rosette at the base may be present or absent. The leaves along the stem are almost always alternately arranged, rarely apparently opposite. The stomata are of the anisocytic type. The genome size of Brassicaceae compared to that of other Angiosperm families is very small to small (less than 3.425 million base pairs per cell), varying from 150 Mbp in "Arabidopsis thaliana" and "Sphaerocardamum" spp., to 2375 Mbp "Bunias orientalis". The number of homologous chromosome sets varies from four
Brassicaceae
4293578
white endosperm, and a vestigial wing; they are dispersed by the pinyon jay, which plucks the seeds out of the open cones. The jay, which uses the seeds as a food resource, stores many of the seeds for later use, and some of these stored seeds are not used and are able to grow into new trees. The Parry pinyon frequently hybridises with single-leaf pinyon ("P. monophylla") where their ranges meet in southern California and northern Baja California. Hybrids are distinguished by intermediate features, with needles usually fascicles of 2–3 with some stomata on the outer surface. It has been
Pinus quadrifolia
17471665
colonise stony soil, boulders and snowy grikes above the treeline. In Europe, it is often found in arctic and boreal regions, while further south it is restricted to montane landscapes and alpine areas. It is also found in Asia, Africa, the Americas, Australia, New Zealand and Antarctica. In some localities, "Polytrichum alpinum" may be confused with "Pogonatum urnigerum". Key distinguishing features are that the spore capsules of the Alpine moss are at the bottom of large single-celled stomata; the capsule outer wall has smooth cells; the leaf sheath is much longer than that of "Pogonatum urnigerum" and the leaf blade
Polytrichum alpinum
14335935
seam of the middle Gore Lignite Measures. "B. novae-zelandiae" was first published in 2010. The specific epithet refers to New Zealand, where the fossils were found. The fossils are assigned to Banksieae based on several structural grounds, including brachyparacytic stomata, a trichome base architecture unique to Banksieae, "banksioid" venation, and the pinnate leaf lobes. Within Banksieae they are assigned to genus "Banksia" because of their cuticular papillae and the division of the leaves into triangular lobes all the way back to the midrib, neither of which occurs in any other Banksieae genus. (Before the 2007 transfer of "Dryandra" into "Banksia",
Banksia novae-zelandiae
14788224
much higher than in the branches of smaller trees (~20 m). Phillips, Bond and Ryan suggested that this is probably due to the branches of taller trees having a lower leaf-to-sapwood ratio than those of small branches. Dye staining shows that cavitation is common in the branches of "S. amara". They concluded that water flux in "S. amara" is controlled by structural (leaf area), rather than physiological (closing stomata) means. Leaves absorb light in the photosynthetically active radiation (PAR) spectrum at wavelengths between 400 nm and 700 nm with a high efficiency, but the efficiency decreases at longer wavelengths. Generally
Simarouba amara
877559
respectively. The rate of evaporation from a leaf can be determined using a photosynthesis system. These scientific instruments measure the amount of water vapour leaving the leaf and the vapor pressure of the ambient air. Photosynthetic systems may calculate water use efficiency ("A/E"), "g", intrinsic water use efficiency ("A/g"), and "C". These scientific instruments are commonly used by plant physiologists to measure CO uptake and thus measure photosynthetic rate. There is little evidence of the evolution of stomata in the fossil record, but they had appeared in land plants by the middle of the Silurian period. They may have evolved
Stoma
3832868
"Nelumbo's" ultrahydrophobicity allows the water droplets to accumulate together very quickly, and then roll off of the leaf very easily at the slightest disturbance of the leaf, a process which allows its stomata to function normally without restriction due to blockage by water droplets. A unique property of the genus "Nelumbo" is that it can generate heat., which it does by using the alternative oxidase pathway (AOX). This pathway involves a different, alternative exchange of electrons from the usual pathway that electrons follow when generating energy in mitochondria, known as the AOX, or alternative oxidase pathway. The typical pathway in
Nelumbo