Eriogonum umbellatum var. polyanthum

(Bentham) M. E. Jones

Contr. W. Bot. 11: 5. 1903.

Common names: American River sulphur flower
Endemic
Basionym: Eriogonum polyanthum Bentham in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 12. 1856
Synonyms: Eriogonum umbellatum subsp. polyanthum (Bentham) S. Stokes
Treatment appears in FNA Volume 5. Treatment on page 351. Mentioned on page 336, 342, 343, 352.

Shrubs, round, rather open, 4–10 × 5–10 dm. Aerial flowering stems erect, 1–2 dm, floccose, without one or more leaflike bracts ca. midlength. Leaves in rather open, terminal rosettes; blade oblanceolate to narrowly elliptic, 1–3 × 0.3–1(–1.3) cm, densely white-tomentose abaxially, thinly floccose or glabrous and light green adaxially, margins plane. Inflorescences umbellate or compound-umbellate, branched 1–2(–3) times; branches thinly floccose or glabrous, occasionally central branch seemingly with a whorl of bracts ca. midlength; involucral tubes 2.5–4 mm, floccose, lobes 2–3.5 mm. Flowers 4–7 mm; perianth bright yellow.


Phenology: Flowering Jun–Sep.
Habitat: Serpentine flats and slopes, oak and montane conifer woodlands
Elevation: 800-1500 m

Discussion

The inflorescences of var. polyanthum are commonly compound-umbellate, but plants with reduced yet bracteated inflorescences do occur. Those with a reduced inflorescence technically consist of a long (6–10 cm), central, bractless peduncle and two lateral branches (3–4 cm), with each of the latter bearing a peduncle (3–6 cm). Such branches seem to have a whorl of leaflike bracts, but actually the bracts are positioned between the branch and involucres (technically at the base of the peduncle) and thus are like other members of the genus.

The name var. polyanthum has been misapplied in California to plants here attributed to var. modocense and var. dumosum.

Selected References

None.

Lower Taxa

None.
James L. Reveal +
(Bentham) M. E. Jones +
Eriogonum polyanthum +
American River sulphur flower +
800-1500 m +
Serpentine flats and slopes, oak and montane conifer woodlands +
Flowering Jun–Sep. +
Contr. W. Bot. +
Eriogonum umbellatum subsp. polyanthum +
Eriogonum umbellatum var. polyanthum +
Eriogonum umbellatum +
variety +