21. Eriogonum mortonianum Reveal, Brittonia. 26: 90, fig. 1. 1974.
Fredonia wild buckwheat
Shrubs, erect to spreading, not scapose, (3-)4-10 × 5-20 dm, essentially glabrous and bright green. Stems spreading, without persistent leaf bases, up to 1/3 height of plant; caudex stems absent; aerial flowering stems erect to spreading, slender, solid, not fistulose, 0.2-2 dm, glabrous. Leaves cauline on proximal 3 of stem, 1 per node; petiole (0.2-)0.3-0.8(-1) cm, floccose or glabrous; blade elliptic, 1.5-4(-4.5) × (0.3-)0.6-1(-1.3) cm, glabrous and green on both surfaces, margins plane. Inflorescences cymose, open, 15-25 × 13-30 cm; branches often with involucres racemosely arranged at tips of inflorescence branches, glabrous; bracts 3, scalelike, triangular, 1-2 mm. Peduncles absent. Involucres 1 per node, turbinate, 2-2.5 × 1.2-1.8(-2) mm, glabrous; teeth 5, erect, 0.2-0.3 mm. Flowers (2-)2.5-3 mm; perianth pale yellow to yellow or whitish, glabrous; tepals connate proximal 4, dimorphic, those of outer whorl obovate, 1-1.3 mm wide, those of inner whorl oblanceolate, 0.8-1 mm wide; stamens included to slightly exserted, 2-2.5 mm; filaments pilose proximally. Achenes brown, 3-3.5 mm, glabrous. 2n = 40.
Flowering Jul-Sep. Red, gypsophilous clay flats and outcrops, mixed grassland, saltbush, and blackbrush communities; of conservation concern; 1400-1600 m; Ariz.
Eriogonum mortonianum is restricted to a series of low, gypsophilous hills southwest of Fredonia, Mohave County.