Rafinesquia

Annuals, 15–150 cm; taprooted. Stems 1–3, erect, simple or distally branched (hollow), glabrous. Leaves basal and cauline; basal petiolate or sessile, blades oblong to oblanceolate, pinnately lobed (lobes broad or narrow); cauline sessile, sometimes auriculate clasping, distal smaller, becoming entire and bractlike. Heads (erect) borne singly (at ends of branches) or in open, paniculiform arrays. Involucres cylindro-conic, (4–)6–15+ mm diam. Calyculi of 8–14, spreading to reflexed, unequal bractlets (lengths to 1/2 phyllaries). Phyllaries 7–20 in 1 series, linear-lanceolate, ± equal, margins scarious, apices acuminate. Receptacles flat, smooth, glabrous, epaleate. Florets 15–30; corollas white, sometimes with rose or purplish veins abaxially (outer surpassing phyllaries). Cypselae tan to mottled grayish brown, fusiform, 9–18(–20) mm, bodies tapering to beaks, ribs or ridges 5, outer usually with antrorse hairs or papillate or scaly indument, inner mostly smooth to cross-rugulose, glabrous; pappi (borne on small discs) ± persistent, of 5–21, white or sordid, ± plumose (at least proximally, barbs sometimes entangled) bristles in 1 series. x = 8.

Distribution

sw United States, nw Mexico.

Discussion

Species 2 (2 in the flora).

Selected References

None.

Lower Taxa

Rafinesquia californica, Rafinesquia neomexicana

Key

1	Ligules surpassing phyllaries by 5–7 mm; cypselae 9–14 mm, including beaks 5–7 mm; pappus bristles wholly plumose, barbs straight, separate	Rafinesquia californica
1	Ligules surpassing phyllaries by 15–20 mm; cypselae 12–18(–20) mm, including beaks 3–6 mm; pappus bristles plumose on proximal 65–80%, barbs crooked, entangled	Rafinesquia neomexicana