POLYGONACEAE

BUCKWHEAT FAMILY

James C. Hickman

Annual to trees, some dioecious
Stem: nodes often swollen
Leaves simple, basal or cauline, alternate, opposite, or whorled, generally entire; stipules 0 or obvious and fused into a generally scarious sheath around stem
Inflorescence: small cluster, axillary or arrayed in cymes or panicles; involucres sometimes subtending 1–many flowers
Flower generally bisexual, small, ± radial; perianth generally 5–6-lobed, base ± tapered, often jointed to pedicel; stamens 2–9, often in 2 whorls; ovary superior, styles generally 3, generally fused at base
Fruit: achene, generally enclosed by persistent perianth, generally 3-angled, ovoid, and glabrous
Genera in family: 50 genera, 1100 species: worldwide, especially n temp; some cultivated for food (Fagopyrum ; Rheum , rhubarb; Rumex , sorrel) or ornamental (Antigonon , coral-vine; Muehlenbeckia ; Polygonum )
Reference: [Ronse Decraene & Akeroyd 1988 Bot J Linn Soc 98:321–371; Reveal et al. 1989 Phytologia 66(2–4):83–414]
Treatments of the 15 eriogonoid genera are based on the monographic work of James L. Reveal, who is gratefully acknowledged.

NEMACAULIS

Species in genus: 1 sp
Etymology: (Latin: thread stem)
Reference: [Reveal & Ertter 1980 Madroño 27:101–109]

Native

N. denudata Nutt.

WOOLLY-HEADS

Annual, prostrate to erect, 4–40 cm, woolly
Leaves basal; stipule 0; petiole indistinct; blade 5–80 mm, linear to oblanceolate
Inflorescence open, 20–80 cm diam; branches wiry; bracts 3 per node, 1–5 mm, generally linear; involucral bracts many, 1–4 mm, oblanceolate, upper surface very woolly; flowers 5–30 per involucre
Flower: perianth 0.8–1.5 mm, greenish white to dark red, glabrous or glandular, lobes 6; stamens 3
Fruit ± 1 mm, brown to black
Ecology: Coastal strand, desert scrub, etc., in sandy soils
Elevation: < 400 m.
Bioregional distribution: Southwestern California, Mojave Desert (Devil's Playground), Sonoran Desert
Distribution outside California: Arizona, nw Mexico