Thelesperma fraternum Shinners; T. megapotamicum (Sprengel) Kuntze var. ambiguum (A. Gray) Shinners

Perennials or subshrubs, 10–30(–50) cm. Cauline leaves crowded to ± scattered over proximal ¹/3–¹/2 of plant heights, internodes mostly 5–50(–80+) mm; lobes mostly linear to filiform, sometimes oblanceolate, (5–)15–75 × 0.5–1(–2) mm. Calyculi of 3–5+ ovate to oblong bractlets 1–3 mm. Ray florets usually 8, rarely 0; laminae yellow, 4–8(–12+) mm. Disc corollas red-brown, throats shorter than lobes. Cypselae 4–5+ mm; pappi usually 1.5–2+ mm, rarely 0. 2n = 44.

Flowering Mar–Jun. Disturbed sites on sands or clays; 10–200 m; N.Mex., Tex.; Mexico (Nuevo León, Tamaulipas).

Thelesperma ambiguum is similar to T. megapotamicum; it may be better treated as a variety of the latter.