117.
Draba verna
Linnaeus, Sp. Pl. 2: 642. 1753.
Whitlow grass, whitlow wort
Draba boerhaavii
(H. C. Hall) Raus;
D. praecox
Steven;
D. verna
var.
aestivalis
Lejeune;
D. verna
var.
boerhaavii
H. C. Hall;
Erophila boerhaavii
(H. C. Hall) Dumortier;
E. krockeri
Andrzejowski;
E. praecox
(Steven) de Candolle;
E. verna
(Linnaeus) L. Chevallier;
E. verna
subsp.
praecox
(Steven) Walters
Annuals;
scapose.
Stems
(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.
Basal leaves
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.
Cauline leaves
0.
Racemes
4-20(-30)-flowered, ebracteate, usually considerably elongated in fruit; rachis usually flexuous, glabrous.
Fruiting pedicels
divaricate to ascending, straight or slightly curved upward, (2-) 5-20(-35) mm, glabrous.
Flowers:
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.
Fruits
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.
Seeds
ovoid (slightly flattened), 0.3-0.6(-0.8) × 0.2-0.4 mm.
2
n
= 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.
Draba verna
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
n =
94, which has not been confirmed by subsequent botanists.
Erophila vulgaris
de Candolle is an illegitimate name for
Draba verna
.
