Linnaeus, Sp. Pl. 2: 642. 1753.
Whitlow grass, whitlow wort
(H. C. Hall) Raus;
H. C. Hall;
(H. C. Hall) Dumortier;
(Steven) de Candolle;
(Linnaeus) L. Chevallier;
(few to many from base), unbranched, (0.2-)0.5-2(-3) dm, pubescent proximally, glabrous distally, trichomes simple and 2(-4)-rayed, 0.1-0.4 mm.
rosulate; petiolate; blade obovate, spatulate, oblanceolate, lanceolate, oblong, or, rarely, linear, 0.2-1.8(-3) cm × (0.5-)1-5(-10) mm, margins entire or 1-5-toothed on each side, surfaces pubescent with simple or stalked, 2-4-rayed trichomes, 0.1-0.5 mm.
4-20(-30)-flowered, ebracteate, usually considerably elongated in fruit; rachis usually flexuous, glabrous.
divaricate to ascending, straight or slightly curved upward, (2-) 5-20(-35) mm, glabrous.
sepals (green or purplish), oblong, 1-2.5 mm, glabrescent or pubescent, (trichomes simple or 2-rayed); petals white, deeply 2-fid, (1.5-)2-4.5(-6) × 1-2 mm; anthers ovate, 0.2-0.4 mm.
obovate, oblanceolate, lanceolate, elliptic, oblong, or linear, plane, flattened, (2.5-)4-9(-12) × 1.5-2.5(-3.5) mm; valves glabrous; ovules (20-)32-70(-84) per ovary; style 0.02-0.2 mm.
ovoid (slightly flattened), 0.3-0.6(-0.8) × 0.2-0.4 mm.
= 14, 16, 20, 24, 28, 30, 32, 34, 36, 38, 40, 52, 54, 58, 60, 64.
Flowering Feb-May. Cedar glades, lawns, fields, pastures, waste places, grassy hillsides, disturbed sites, roadsides; 0-2500 m; introduced; Alta., B.C., N.B., Ont., Que.; Ala., Ark., Calif., Conn., Del., D.C., Ga., Idaho, Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Miss., Mo., Mont., Nev., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., R.I., S.C., Tenn., Utah, Vt., Va., Wash., W.Va., Wyo.; Europe; Asia; nw Africa; introduced also in Central America, South America, Australia.
represents a highly variable and taxonomically difficult complex within which species, subspecies, varieties, and forms have been named (O. E. Schulz 1927); only those synonyms pertaining to North America are listed above. Most of the taxonomic difficulties are the results of disploidy, autogamy, and hybridization. The morphological extremes are connected by intermediate forms in every conceivable character. Furthermore, there appears to be no correlation between morphology, cytology, geography, and ecology to support the division of this complex into meaningful taxa. A complex cytological picture was presented by Ø. Winge (1940), including the highest count of 2
94, which has not been confirmed by subsequent botanists.
de Candolle is an illegitimate name for