Herbs, narrowly erect, (0.5-)1-6 dm, tomentose, whitish to grayish. Stems: aerial flowering stems erect, (0.3-)1-3 dm, tomentose. Leaves cauline; petiole 0.3-1.5 cm; blade narrowly oblanceolate to broadly elliptic, (0.7-)1-3 × 0.5-1.5 cm, densely white-tomentose and whitish to grayish on both surfaces. Inflorescences narrowly cymose, distally uniparous due to suppression of secondary branches, open, (5-)10-50 × 10-25 cm; branches tomentose; bracts 1.5-3 × 1-2.5 mm. Peduncles absent. Involucres appressed to branches, turbinate, 1.5-2.5 × 1-2 mm, tomentose, rarely glabrous; teeth 5, erect, 0.4-1 mm. Flowers (1-)1.5-2 mm; perianth white, becoming pink or red, glabrous; tepals dimorphic, those of outer whorl broadly fan-shaped, those of inner whorl oblanceolate; stamens included, 1-1.5 mm; filaments pilose proximally. Achenes dark brown, 3-gonous, 1-1.3 mm. 2n = 26.
Flowering year-round. Sandy to gravelly washes, flats, and slopes, saltbush, creosote bush, greasewood, blackbrush, and sagebrush communities, oak, pinyon and/or juniper, and montane conifer woodlands; (200-)500-2200(-2500) m; Ariz., Calif., N.Mex., Tex., Utah; Mexico (Chihuahua, Durango, Sonora).
Eriogonum polycladon is widely distributed from near Needles, San Bernardino County, California (where not found since the 1930s), eastward to western Texas, and from southern Utah throughout much of central and southern Arizona into western and southern New Mexico. It is found also in the Mexican states of Chihuahua, Durango, and Sonora. It can be locally common and occasionally weedy, especially in southeastern Arizona and southwestern New Mexico.
Duration: Annual
Nativity: Native
Lifeform: Forb/Herb
General: Annual herb, 15-60 cm tall, from a slender taproot; stems erect, whitish- to grayish-tomentose, branching in the inflorescence, the branches narrowly ascending to erect, emerging at a narrow angle.
Leaves: Alternate along the stem, on petioles 3-15 mm long; blades lanceolate or oblanceolate, 5-15 mm long, densely tomentose on both surfaces, with margins curled under.
Flowers: Pink to white, in loose clusters of 10 or fewer short-stalked flowers held together by cup-shaped structures called involucres. Involucres sessile and arranged in racemes along the upper branches. Each individual flower is 1-2 mm high, with 6 ruffled petal-like tepals, these pink or whitish.
Fruits: Achenes trigonous, about 1 mm long, dark brown.
Ecology: Found on roadsides and in washes, from 2,500-7,500 ft (760-2286 m); flowers June-November.
Distribution: UT, AZ, NM, s TX; south to n MEX.
Notes: This annual wild buckwheat is distinguished by its slender growth form, leaves and stems covered with long hairs (tomentose), leaves with curled-under margins scattered along the stem, and white or pink flowers. Host plant for Rita Blue butterfly. There are a number of quite similar annual buckwheats, so it is wise to make a collection. Eriogonum cernuum is one of the more common similar species. It is distinguished from this species by its leaves, which are white to gray-hairy mostly on the underside (E. polycladon leaves are densely hairy in both surfaces); its glabrous stems (E. polycladon has tomentose stems); and its flower clusters (involucres) which are on often-dangling stalks 1-2 cm long (E. polycladon has sessile involucres.)
Ethnobotany: Unknown
Etymology: Eriogonum is from the Greek erion, wool, and gony, knee, alluding to the hairy nodes of the first species described, E. tomentosum; polycladon means many-branched.
Synonyms: Eriogonum densum, E. vimineum var. densum
Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2017
