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AMARANTHACEAE

AMARANTH FAMILY

James Henrickson

Annual to tree
Stem prostrate to erect
Leaves alternate or opposite, simple, generally entire, bract-like upward; stipules 0
Inflorescence: cymes, often arrayed ± in spikes or panicles; bracts 1–3 per flower, generally membranous-scarious, tip often short-pointed or spine-like
Flower generally small, uni- or bisexual, radial; sepals 0–5, fused at base or free, often ± scarious; petals 0; stamens 0–5, opposite sepals (staminodes sometimes alternating), filaments sometimes fused at base; ovary superior, 1-chambered, ovules 1–several, erect or pendent on ± basal stalks, styles 0–3, stigma head-like or 2–3-lobed
Fruit: utricle to circumscissile capsule
Seed lenticular to spheric, hard
Genera in family: ± 65 genera, ± 900 species: tropical, subtropical
Reference: [Robertson 1981 J Arnold Arbor 62:267–313]

AMARANTHUS

PIGWEED, AMARANTH

Annual, monoecious or dioecious
Leaves alternate; blade linear to ovate
Inflorescence: cymes in dense, spike-like clusters; bract 1, tip generally short-pointed or -spined, generally scarious; bractlets 0–2
Staminate flower: sepals 3–5, ± equal, ± as bracts; stamens (1)3–5, filaments free; staminodia 0
Pistillate flower: sepals (3–)5, ± equal, scarious except midvein, fused at base, falling with fruit; ovary compressed-ovoid, styles (2)3, stigmas slender, papillate, ovule 1, erect
Fruit circumscissile or indehiscent, smooth or inflated-wrinkled; walls membranous to spongy-hardened
Seed 1, lenticular, smooth, reddish to black
Species in genus: ± 60 species: worldwide; some potherbs, some cultivated for seed
Etymology: (Greek: unfading, from persistent bracts and sepals)
Some species (especially A. cruentus, A. powellii, A. retroflexus) hybridize complexly
Reference: [Tucker & Sauer Madroño 1958 14:252–261]

Native

A. torreyi (A. Gray) Benth.

Plant erect, 1–7 dm, monoecious
Leaf: petiole 4–16 mm; blade 12–50 mm, oblanceolate to ovate
Inflorescence: axillary clusters scattered to stem base, crowded above into terminal, leafy spike < or = 10 cm, 7–15 mm wide; bracts 1.3–3.5 mm, midrib green, margins scarious below, sparsely glandular-hairy
Staminate flower: sepals 5, 2.5–4 mm; stamens 3
Pistillate flower: sepals 5, 1.4–2.5 mm, narrowly spoon-shaped, tips rounded to slightly notched, jagged
Fruit 1.4–2 mm, circumscissile; lid coarsely wrinkled-inflated near base
Seed ± 1 mm wide, black
Ecology: Uncommon. Sandy flats, arroyos, after late summer rains
Elevation: 1200–1700 m.
Bioregional distribution: Mojave Desert
Distribution outside California: w Arizona

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