Are both Todea and Stephanocereus names for plant genus'?
yes
Stephanocereus
Stephanocereus is genus of cactus from Brazil, related to "Arrojadoa".
 This genus was monotypic until "Pilosocereus luetzelburgii" was included here, resulting in the combination "Stephanocereus luetzelburgii".
Todea
The fern genus Todea is known from only two living species. "
Todea barbara" L., known as the king fern, is native to South Africa, New Zealand, and Australia while "Todea papuana" H. is known only from Papua New Guinea.
 Species in the genus "Todea", as "Leptopteris", are distinct from other in Osmundaceae in that sporangia are born on laminar pinnules.
Nemacaulis
Nemacaulis is a monotypic plant genus in the buckwheat family containing the single species Nemacaulis denudata, which is known by the common names woollyheads and cottonheads.
 This plant is a somewhat nondescript delicate annual herb with thin, spindly, naked stems and woolly white flowerheads.
 It can be found in sandy habitats in California, Arizona, and northern Mexico. Glaucocarpum
Glaucocarpum is a monotypic plant genus containing the single species Glaucocarpum suffrutescens (syn.
 "Hesperidanthus suffrutescens", "Schoenocrambe suffrutescens"), a rare species of flowering plant in the mustard family known by the common names Uinta Basin waxfruit, waxfruit mustard, toad-flax cress, and shrubby reed-mustard.
 It is endemic to Utah in the United States, where it is known only from Duchesne and Uintah Counties.
 It is threatened by habitat degradation and destruction.
 It is federally listed as an endangered species of the United States. Croton (plant)
Croton is an extensive flowering plant genus in the spurge family, Euphorbiaceae.
 The plants of this genus were described and introduced to Europeans by Georg Eberhard Rumphius.
 The common names for this genus are rushfoil and croton, but the latter also refers to "Codiaeum variegatum".
 The generic name comes from the Greek κρότος ("krótos "), which means "tick" and refers to the shape of the seeds of certain species. Centaurea
Centaurea ( ) is a genus of between 350 and 600 species of herbaceous thistle-like flowering plants in the family Asteraceae.
 Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich.
 Common names for this genus are centaury, centory, starthistles, knapweeds, centaureas and the more ambiguous "bluets"; a vernacular name used for these plants in parts of England is "loggerheads" (common knapweed).
 The "Plectocephalus" group – possibly a distinct genus – is known as basketflowers.
 "Cornflowers" is used for a few species, but that term more often specifically means "C. cyanus" (sometimes also called "basket flower").
 The common name "centaury" is sometimes used, although this also refers to the unrelated plant genus "Centaurium". List of Lithocarpus species
The "World Checklist of Selected Plant Families" and "The Plant List" recognise about 330 accepted taxa (of species and infraspecific names) in the plant genus "Lithocarpus" of the beech family Fagaceae. Mandragora officinarum
Mandragora officinarum is the type species of the plant genus "Mandragora".
 It is often known as mandrake, although this name is also used for other plants.
 s of 2015 , sources differ significantly in the species they use for "Mandragora" plants native to the Mediterranean region.
 In the narrowest circumscription, "M. officinarum" is limited to small areas of northern Italy and the coast of former Yugoslavia, and the main species found around the Mediterranean is called "Mandragora autumnalis", the autumn mandrake.
 In a broader circumscription, all the plants native to the countries around the Mediterranean Sea are placed in "M. officinarum", which thus includes "M. autumnalis".
 The names autumn mandrake and Mediterranean mandrake are then used.
 Whatever the circumscription, "Mandragora officinarum" is a perennial herbaceous plant with ovate leaves arranged in a rosette, a thick upright root, often branched, and bell-shaped flowers followed by yellow or orange berries. List of Diospyros species
s of July 2014 the "World Checklist of Selected Plant Families" and "The Plant List" recognise about 750 accepted taxa (of species and infraspecific names) in the plant genus "Diospyros". List of Scleria species
s of June 2014 "The Plant List" recognises about 266 accepted taxa (of species and infraspecific names) in the plant genus "Scleria".