92.
Draba reptans
(Lamarck) Fernald, Rhodora. 36: 368. 1934.
Arabis reptans
Lamarck in J. Lamarck et al., Encycl. 1: 222. 1783;
Draba caroliniana
Walter;
D. caroliniana
var.
dolichocarpa
O. E. Schulz;
D. caroliniana
var.
hunteri
Payson & H. St. John;
D. caroliniana
var.
micrantha
(Nuttall) A. Gray;
D. caroliniana
subsp.
stellifera
(O. E. Schulz) Payson & H. St. John;
D. caroliniana
var.
umbellata
Torrey & A. Gray;
D. coloradensis
Rydberg;
D. hispidula
Michaux;
D. micrantha
Nuttall;
D. reptans
var.
micrantha
(Nuttall) Fernald;
D. reptans
subsp.
stellifera
(O. E. Schulz) Abrams;
D. reptans
var.
stellifera
(O. E. Schulz) C. L. Hitchcock;
D. umbellata
Muhlenberg;
Tomostima caroliniana
(Walter) Rafinesque;
T. hispidula
(Michaux) Rafinesque;
T. micrantha
(Nuttall) Lunell
Annuals;
scapose or subscapose.
Stems
(simple or few from, or distal to, base), unbranched, (0.1-)0.3-1.2 (-1.6) dm, sparsely to densely pubescent proximally, trichomes 2 (or 3)-rayed, 0.1-0.6 mm, sometimes with simple or spurred ones, to 0.9 mm, distally usually glabrous, rarely with few trichomes.
Basal leaves
not rosulate; petiole obscure; blade elliptic or spatulate to obovate or suborbicular, 0.5-2.3(-3) cm × 1.5-8(-13) mm, margins entire, surfaces pubescent abaxially with stalked, 2-4-rayed trichomes, 0.1-0.5 mm, adaxially with simple trichomes, 0.6-1 mm, with stalked, 2-rayed ones, to 0.7 mm.
Cauline leaves
usually 0, rarely 1-3; sessile; blade similar to basal.
Racemes
(3-)5-12(-16)-flowered, ebracteate, (subumbellate), not elongated in fruit; rachis not flexuous, usually glabrous, rarely sparsely pubescent.
Fruiting pedicels
horizontal to divaricate-ascending, straight, (1-)2-7(-9) mm, glabrous or glabrate.
Flowers:
(late-season ones cleistogamous, apetalous); sepals oblong, 1.5-2.3 mm, pubescent, (trichomes simple); petals (rarely absent), white, spatulate, 2-4.5 × 1-1.5 mm; anthers ovate, 0.4-0.5 mm.
Fruits
linear to linear-oblong, plane, flattened, (5-)7-16(-20) × 1.2-2.3 mm; valves glabrous or pubescent, trichomes usually simple and antrorse, 0.1-0.3 mm, rarely with fewer, spurred or 2-rayed ones; ovules 32-88 per ovary; style 0.02-0.1 mm.
Seeds
oblong to ovoid, 0.5-0.8 × 0.3-0.5 mm.
2
n
= 16, 30, 32.
Flowering Feb-Jun(-Aug). Rock outcrops, dry slopes and hillsides, prairies, glades, roadsides, disturbed sites; 0-3000 m; Alta., B.C., Man., Ont., Sask.; Ala., Ariz., Ark., Calif., Colo., Ga., Idaho, Ill., Iowa, Kans., Mass., Mich., Minn., Mo., Mont., Nebr., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., S.C., S.Dak., Tenn., Tex., Utah, Wash., Wis., Wyo.
Draba reptans
is often confused with
D. cuneifolia
, but the two are easily separated. The rachises and pedicels of
D. reptans
are usually glabrous (rarely with a few isolated trichomes); those of
D. cuneifolia
are always densely pubescent. Interestingly, both species show parallel variations in chromosome number; it is currently unclear whether this variation is real or the result of misidentified specimens and/or erroneous counts.
