Amaranthus L.
Annual, rarely perennial, usually monoecious, sometimes dioecious, prostrate to erect herbs. Lvs alternate, entire. Infl. cymose, composed of axillary or terminal spikes; spikes sessile or pedunculate, solitary or clustered (paniculate). Fls densely arranged and each subtended by a bract and 2 bracteoles; bracts and bracteoles occasionally spiny, often varying in length in each cymose cluster. Tepals (2)-3 or (4)-5, membranous, green, brown, red, or hyaline, persistent. Stamens as many as tepals, free; staminodes 0. Stylar branches 2-3-(4), with stigmatic surface to near base; ovule 1, sessile. Fr. dry, membranous, indehiscent, or dehiscent and circumscissile; pericarp usually smooth, enclosed in persistent perianth. Seed usually glossy, smooth and black or dark brown.
Key
c. 60 spp., tropical and subtropical regions. Naturalised spp. 11.
Amaranths are commonly found as weeds of waste and dry places in towns and cities and are well-known in temperate countries as casual adventives around docks, railway yards and other places where merchandise enters the country. N.Z. is no exception, and additional spp. to those described below can be expected to occur at any time. The small seeds are also found as impurities in crop seeds. The spp. that are fully naturalised here show an enormous range of stature according to environmental conditions. Unless otherwise stated, mention of perianth and tepals refers to ♀ fls.
