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.

CHORIZANTHE

SPINEFLOWER

Annual, perennial herb, glabrous or hairy, sometimes glandular
Stem generally scapose (made up of inflorescence axes)
Leaves basal (rarely some cauline); stipule 0; blade generally ± oblanceolate
Inflorescence open or of few heads, sometimes 1-sided; bracts generally opposite, leaf-like to scale-like; involucres 1–several per axil, sessile, tube cylindric to bell-shaped, generally ± cross-ridged or net-veined, bracts (and ribs) 3–6, awns straight or hooked; flowers 1–2 per involucre
Flower: perianth white to red or yellow, lobes 6, entire to fringed or toothed; stamens 3–9
Fruit 1.5–4.5 mm, generally ± brown, glabrous
Species in genus: 50 species: temp w North America, sw South America
Etymology: (Greek: divided flower, from perianth)
Reference: [Reveal & Hardham 1989 Phytologia 66(2):98–198]

Native

C. polygonoides Torr. & A. Gray

KNOTWEED SPINEFLOWER

Stem prostrate, 1–15 cm, greenish or reddish, soft-hairy
Leaf: blade 3–10 mm, thinly hairy
Inflorescence: involucral tube 1.5–2.5 mm, bell-shaped, 3-angled, often reddish, thinly hairy, prominent bracts 3, 1.5–3 mm, spreading, awns hooked (0–2 smaller bracts between larger), none leaf-like
Flower: perianth 1.5–2 mm, white to rose, densely hairy; stamens 9, attached near top of perianth tube
Chromosomes: n=20
Ecology: Diverse sandy to gravelly places
Elevation: < 1400 m.
Bioregional distribution: Northwestern California, Cascade Range, n Sierra Nevada Foothills, Sacramento Valley, Central Western California, Peninsular Ranges
Distribution outside California: n Baja California

Native

var. polygonoides

Plant generally greenish
Inflorescence: involucre (including awns) generally ± 5 mm, tube 2–3 mm, bracts 1.5–2 mm including awns
Ecology: Habitat of sp.
Bioregional distribution: Northwestern California, Cascade Range, n Sierra Nevada Foothills, Sacramento Valley, Central Western California.