Xanthisma spinulosum var. glaberrimum
Sida 20: 1408. 2003.
Perennials, 20–50 cm, often woody at base. Stems stiffly erect, branched in distal 1/3; mid internodes 2–5 mm. Leaves numerous, strictly ascending, not reduced distally, margins pinnatifid, lobes oblong-lanceolate to triangular, 2–7 mm, faces usually glabrous, sometimes lightly tomentose, eglandular. Heads 2–10+, (subsesssile) usually clustered. Peduncles relatively terminal and lateral, 0.5–2 cm. Involucres 8–15 mm wide. 2n = 8, 16.
Phenology: Flowering spring–fall.
Habitat: Sandy to gravelly prairies, hillsides, and roadsides
Elevation: 800–1400 m
Colo., Iowa, Kans., Nebr., N.Mex., N.Dak., Okla., Tex., Wyo.
G. L. Nesom (2003) recognized Xanthisma spinulosum var. glaberrium at species level, as it occurs sympatrically with variety spinulosum in the Texas panhandle, where the two taxa behave like biological species; on the eastern plains of Colorado, however, hybridization and autoploidy have been documented (D. P. Hauber 1986).
"spreading" is not a number.