Strawflower wild buckwheat

Eriogonum microtheca Nuttall subsp. helichrysoides Gandoger, Bull. Soc. Roy. Bot. Belgique 42: 192. 1906; E. effusum Nuttall subsp. helichrysoides (Gandoger) S. Stokes; E. effusum var. rosmarnioides Bentham

Shrubs, spreading, not scapose, 1.5-3(-4) × 3-8 dm, floccose and dark green. Stems spreading, often without persistent leaf bases, up to 1/ 3 height of plant; caudex stems absent; aerial flowering stems erect to slightly spreading, slender, solid, not fistulose, 0.02-0.04 dm, floccose. Leaves cauline, 1 per node; petiole 0.2-0.7 cm, floccose; blade linear to linear-oblanceolate, (2-)3-6 × 0.1-0.3 cm, densely tomentose abaxially, floccose and green adaxially, margins revolute.  Inflorescences cymose, compact, 0.5-1.3(-1.6) dm; branches dichotomous, floccose to nearly glabrous; bracts 3, scalelike, triangular, 0.5-2 mm. Peduncles absent or erect, 0.5-2.5 cm, floccose.  Involucres 1 per node, turbinate, 2.5-3 × 1-2 mm, floccose or glabrous; teeth 5, erect, 0.3-0.6 mm. Flowers 2-2.5(-3) mm; perianth white, becoming rose, glabrous; tepals connate proximal 4, essentially monomorphic, elliptic to obovate; stamens exserted, 2.5-4.5 mm; filaments sparsely pilose. Achenes brown, 2-2.5 mm, glabrous.

Flowering Jul-Sep. Clay slopes or chalky limestone outcrops, mixed grassland communities; 900-1100 m; Kans.

Eriogonum helichrysoides is limited to west-central Kansas (Ellis, Gove, Lane, Logan, Scott, and Trego counties). The plants' dark green color and narrow leaf blades readily segregate the species from E. effusum.