Perennial subscapose glabrous herbs, with thick roots', pinnately decompound leaves, and white flowers (in our species) in peduncled umbels. Involucre of several bracts or none. Involucels of 1 to numerous bracts. Calyx-teeth rather prominent. Petals inflexed at the apex. Stylopodium depressed. Fruit globose, ovoid or ellipsoid, flattened laterally or not at all. Carpels dorsally flattened, with 3-5 flat equal wings; oil-tubes several or solitary in the intervals, few or several on the commissural side. [Greek, wave-winged, referring to the fruit.]

About 13 species, natives of western and central North America, the following typical.

1. Cymopterus Acaùlis (Pursh) Rydberg. Plains Cymopterus

Fig. 3145

Selinum acaule Pursh, Fl. Am. Sept. 732. 1814.

Cymopterus glomeratus Raf. Journ. Phys. 89: 100. 1819.

Cymopterus acaulis Rydberg, Bot. Surv. Neb. 3: 38. 1894.

Low, the stem seldom over 1' high. Leaves erect or ascending, bright green, 3'-8' long, slender-petioled, pinnate or bipinnate into linear-oblong obtuse entire or lobed segments; umbels slender-peduncled, compact, 1' or less broad, several-rayed; rays only 1"-2 1/2" long; pedicels very short; involucre none; involucel of a single palmately-lobed bractlet; fruit broadly oval, about 3" in diameter when mature; oil-tubes 4-5 in the intervals; seed-face nearly flat.

In dry soil, Minnesota, Wisconsin and Iowa to Arkansas, Assiniboia, British Columbia and Colorado. April-May.