Wildflowers of Southern Arizona
Buckwheat (Polygonaceae) family.
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.) 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.
Santa Catalina Mountains.
Location: Arizona Trail 0.25 mile beyond campground road.
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