Annuals, 5–85 cm (herbage glabrous); taprooted (roots deep, slender to thick). Stems usually 1, erect, simple proximally, branched distally, glabrous. Leaves cauline (opposite proximally); ± sessile; blades linear to filiform, margins entire. Heads borne singly. Peduncles not inflated distally, usually bracteate. Calyculi of 8, ovate to lanceolate bractlets. Involucres narrowly cylindric, 4–5 mm diam. Phyllaries 8 in 1–2 series, linear, margins scarious, apices acute (keeled). Receptacles flat, pitted, glabrous, epaleate. Florets 8–11; corollas pale purple or lavender, with white-tips. Cypselae pale green or tan, subcylindric to ± fusiform, apices abruptly constricted, not beaked, ribs 8–10, scabrous distally; pappi of 30–50, basally connate, white, ± equal, smooth or barbellulate bristles in ± 1 series. x = 6.

Distribution

c North America.

Discussion

Species 1.

Shinnersoseris rostrata was included in Lygodesmia; Tomb presented evidence for placing it in a separate genus. It differs from Lygodesmia in having opposite proximal leaves, shorter, obscure ligules, shorter style branches, 8–10-ribbed cypselae, echinate pollen, and a different base chromosome number (x = 9 in Lygodesmia.)

Selected References

None.

Lower Taxa

Shinnersoseris rostrata