Flora of North America species comparison

1–several, ascending or decumbent, often branched distally, 3–10 dm, sericeous-tomentose with white hairs.

without nodal spines (Amaranthus spinosus sometimes with paired nodal spines).

usually crowded at base, few on stems, sessile or short-petiolate;

blade lanceolate, proximal leaves 3–12 × 0.5–2.5 cm, base attenuate, apex acute or rarely obtuse, scaberulous or canescent adaxially, sericeous-tomentose with bright whitish hairs abaxially.

alternate or opposite, exstipulate, usually petiolate;

blade margins entire (entire or serrulate in Iresine; entire, crispate, or erose in Amaranthus).

cymules arranged in spikes, panicles, thyrses, heads, glomerules, clusters, or racemes; each flower subtended by 1 bract and 2 bracteoles (latter sometimes 1 or absent in Amaranthus).

dense, stout, flowers arranged in 3-ranked spiral;

bracteoles dark, glabrous.

(3.5–)4–5.5 mm;

perianth lobes narrowly oblong, apex obtuse, or acutish, pubescence dense, bright white;

filament lobes stramineous or darkened, blunt.

bisexual or unisexual (plants then monoecious or dioecious), hypogynous, generally small or minute;

tepals mostly (1–)4–5 or absent, distinct or connate into cups or tubes, scarious, chartaceous, membranaceous, or indurate;

stamens 2–5, filaments basally connate into cups or tubes, rarely distinct, alternating with pseudostaminodes (appendages on staminal tubes) or not, anthers 2-locular with 1 line of dehiscence or 4-locular with 2 lines of dehiscence;

ovary superior, 1-locular;

ovules 1 or, rarely, 2–many;

style 1 or absent;

stigmas 1–3(–5).

utricles, dry, dehiscent or not.

black, reddish brown, or brown, lenticular, subglobose or globose (rarely cylindric), usually small;

embryo peripheral, surrounding mealy perisperm.

narrowly or broadly winged laterally, 2.5–5.5 × 3–4.5 mm, longer than broad, wing margins irregularly dentate, 1 or both surfaces of perianth with 1 or more basal tubercles or spines.