Are both Oxypetalum and Metasequoia types of trees?
no
Metasequoia
Metasequoia (dawn redwood) is a fast-growing, deciduous tree, and the sole living species, "Metasequoia glyptostroboides", is one of three species of conifers known as redwoods.
 It is native to Lichuan county in Hubei province, China.
 Although the least tall of the redwoods, it grows to at least 200 feet (60 meters) in height.
 Local villagers refer to the original tree from which most others derive as "Shui-sa", or "water fir", which is part of a local shrine.
 Since its rediscovery in 1944, the dawn redwood has become a popular ornamental.
Oxypetalum
Oxypetalum is a genus of flowering plants in the Apocynaceae family, first described with this name in 1810.
 The genus is native to South America.
Sequoia (genus)
Sequoia is a genus of redwood coniferous trees in the subfamily Sequoioideae of the family Cupressaceae.
 The only extant species of the genus is "Sequoia sempervirens" in the Northern California coastal forests ecoregion of Northern California and Southwestern Oregon in the United States.
 The two other genera, "Sequoiadendron" and "Metasequoia", in the subfamily Sequoioideae are closely related to "Sequoia".
 It includes the largest trees in the world. Sequoiadendron giganteum
Sequoiadendron giganteum (giant sequoia; also known as giant redwood, Sierra redwood, Sierran redwood, Wellingtonia or simply Big Treea nickname used by John Muir) is the sole living species in the genus "Sequoiadendron", and one of three species of coniferous trees known as redwoods, classified in the family Cupressaceae in the subfamily Sequoioideae, together with "Sequoia sempervirens" (coast redwood) and "Metasequoia glyptostroboides" (dawn redwood).
 The common use of the name "sequoia" generally refers to "Sequoiadendron giganteum", which occurs naturally only in groves on the western slopes of the Sierra Nevada Mountains of California. GiST
In computing, GiST or Generalized Search Tree, is a data structure and API that can be used to build a variety of disk-based search trees.
 GiST is a generalization of the B+ tree, providing a concurrent and recoverable height-balanced search tree infrastructure without making any assumptions about the type of data being stored, or the queries being serviced.
 GiST can be used to easily implement a range of well-known indexes, including B+ trees, R-trees, hB-trees, RD-trees, and many others; it also allows for easy development of specialized indexes for new data types.
 It cannot be used directly to implement non-height-balanced trees such as quad trees or prefix trees (tries), though like prefix trees it does support compression, including lossy compression.
 GiST can be used for any data type that can be naturally ordered into a hierarchy of supersets. Not only is it extensible in terms of data type support and tree layout, it allows the extension writer to support any query predicates that they choose.
 The most widely used GiST implementation is in the PostgreSQL relational database; it was also implemented in the Informix Universal Server, and as a standalone library, libgist. Hammock (ecology)
Hammock is a term used in the southeastern United States for stands of trees, usually hardwood, that form an ecological island in a contrasting ecosystem.
 Hammocks grow on elevated areas, often just a few inches high, surrounded by wetlands that are too wet to support them.
 The term hammock is also applied to stands of hardwood trees growing on slopes between wetlands and drier uplands supporting a mixed or coniferous forest.
 Types of hammocks found in the United States include tropical hardwood hammocks, temperate hardwood hammocks, and maritime or coastal hammocks.
 Hammocks are also often classified as hydric (wet soil), mesic (moist soil) or xeric (dry soil).
 The types are not exclusive, but often grade into each other. Weeping tree
Weeping trees are characterized by soft, limp twigs.
 This characterization may lead to a bent crown and pendulous branches that can cascade to the ground.
 While weepyness occurs in nature, most weeping trees are cultivars. Because of their shape, weeping trees are popular in landscaping; generally they need a lot of space and are solitary so that their effect is more pronounced.
 There are over a hundred different types of weeping trees.
 Some trees, such as the cherry, have a variety of weeping cultivars. Artificial Christmas tree
An artificial Christmas trees is an artificial pine and fir tree manufactured for the specific purpose of use as a Christmas tree.
 The earliest artificial Christmas trees were wooden, tree-shaped pyramids or feather trees, both developed by Germans.
 Most modern trees are made of polyvinyl chloride (PVC) but many other types of trees have been and are available, including aluminum Christmas trees and fiber-optic illuminated Christmas trees. Forests of KwaZulu-Natal
Areas of forest which grow in KwaZulu-Natal, South Africa mostly on south facing slopes in higher rainfall areas, and along the humid coastal areas.
 Different types of forest can be identified by their species composition which depends mostly on the altitude, latitude and substrate (soil and rock types) in which they grow.
 South facing slopes are favourable for the development of forest as they are more shaded, and therefore cooler and retain more moisture than the northern slopes.
 The extra moisture on the south slopes is not only favoured by forest trees, but also helps to prevent or subdue wildfires.
 Fires can also be blocked by cliff faces and rocks or boulders on these slopes, and by streams or rivers at the base of the slopes.
 The coastal regions are conducive to forest formation, because of high rainfall and humidity which are favoured by forest trees and also help to prevent or subdue fires.
 The rivers of the coastal areas are also broader than further inland, which may often prevent fires from spreading long distances, and fires generally burn uphill and therefore more often away from areas at low altitude. Empty category
In linguistics, in the study of syntax, an empty category is a nominal element that does not have any phonological content and is therefore unpronounced.
 Empty categories may also be referred to as covert nouns, in contrast to overt nouns which are pronounced.
 The phenomenon was named by Noam Chomsky in his 1981 framework.
 Some empty categories are governed by the empty category principle.
 When representing empty categories in trees, linguists use a null symbol to depict the idea that there is a mental category at the level being represented, even if the word(s) are being left out of overt speech.
 There are four main types of empty categories: NP-trace, Wh-trace, PRO, and "pro".
 The types are differentiated by their two binding features: the anaphoric feature [a] and the pronominal feature [p].
 The four possible combinations of plus or minus values for these features yield the four types of empty categories.
 Empty categories are present in most of the world's languages, although different languages allow for different categories to be empty.