Draba brachycarpa |
Draba pennellii |
|
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short-pod whitlowgrass, shortfruit Draba, shortpod Draba |
schell creek Draba |
|
Habit | Annuals; not scapose. | Perennials; (cespitose, often forming mats); caudex branched (elongated, with persistent leaf bases, branches sometimes terminating in sterile rosettes); sometimes scapose. |
Stems | usually branched, rarely unbranched, (0.3–)0.4–1.9(–2.2) dm, pubescent throughout, trichomes sessile, cruciform, 0.2–0.6(–0.8) mm (rays often equal, or those parallel to stem axis longer). |
unbranched, (0.15–)0.3–0.7(–1) dm, pubescent proximally, trichomes simple and spurred, 0.4–0.8 mm, and short-stalked, 2–4-rayed, 0.1–0.4 mm, (sometimes with simple trichomes distally). |
Basal leaves | not rosulate; petiolate; petiole (to 0.5 cm), not ciliate; blade oblanceolate to obovate, 0.5–2 cm × 2–8 mm, margins entire, surfaces pubescent, trichomes cruciform, 0.2–0.6(–0.8) mm. |
subrosulate; sessile; blade oblanceolate to oblong, (0.3–)0.5–0.8 cm × 1–3 mm, (base ciliate, trichomes simple, 0.2–0.8 mm), margins entire, (not ciliate), surfaces usually pubescent, with stalked, (2–)4 (or 5)-rayed trichomes, 0.2–0.5 mm, adaxially sometimes glabrate, or primarily with simple trichomes, 0.3–0.8 mm. |
Cauline leaves | (4–)6–11; sessile; blade lanceolate to oblong or linear, margins entire, surfaces pubescent as basal. |
(0 or) 1–4; sessile; blade ovate to oblong, margins entire, surfaces pubescent as basal. |
Racemes | (main branch) (20–)25–65(–74)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
(3–)7–15(–20)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | (late ones cleistogamous, apetalous); sepals (green or pink), oblong, 0.7–1.2(–1.5) mm, pubescent; petals white, spatulate, 2–3 × 0.8–1.1 mm; anthers ovate, 0.15–0.25 mm. |
sepals ovate to oblong, 2–3 mm, pubescent, (trichomes simple, with fewer, short-stalked, 2-rayed ones); petals white, obovate, 3.5–6 × 1.5–2.8 mm; anthers oblong, 0.5–0.6 mm. |
Fruiting pedicels | horizontal to divaricate-ascending, straight, (1–)1.5–4(–5) mm, pubescent, trichomes cruciform. |
divaricate-ascending to ascending, straight, 3–10 mm, pubescent, trichomes simple and short-stalked, 2–4-rayed, (0.1–0.4 mm). |
Fruits | usually elliptic to linear-elliptic, rarely ovate-elliptic, plane, flattened, (2–)2.5–5(–6) × 0.9–1.4(–1.9) mm; valves glabrous; ovules 8–16(–20) per ovary; style 0.05–0.1 mm. |
broadly or, rarely, narrowly lanceolate to elliptic or ovate, plane or slightly twisted, flattened, (4)5–8(–10) × 2–3.2 mm; valves (each with distinct midvein), pubescent, trichomes simple and short-stalked, 2-rayed, 0.08–0.2 mm; ovules 12–24 per ovary; style (0.7–)1–1.8(–2.1) mm. |
Seeds | (winged), ovoid, 0.5–0.7 × 0.4–0.5 mm. |
oblong, 0.9–1.3 × 0.7–1 mm. |
2n | = 16. |
= 32. |
Draba brachycarpa |
Draba pennellii |
|
Phenology | Flowering Feb–May. | Flowering May–Jul. |
Habitat | Open woods, cedar glades, pastures and lawns, roadsides, disturbed sites | Rock outcrops and talus slopes in pinyon-juniper, sagebrush, mountain shrub, and mixed conifer communities |
Elevation | 0-300 m (0-1000 ft) | 1900-3500 m (6200-11500 ft) |
Distribution |
AL; AR; AZ; FL; GA; IL; IN; KS; KY; LA; MO; MS; NC; OH; OK; OR; SC; TN; TX; VA
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NV |
Discussion | Draba brachycarpa is closely related to D. aprica and the two are sometimes confused. It is readily distinguished by having leaves with sessile (versus stalked) trichomes, glabrous (versus pubescent) fruits, and smaller (0.5–0.7 versus 0.9–1.1 mm) seeds. The records from Arizona and Oregon are based on old collections, Porter 802 (Devil’s Canyon, 22 Feb 1926, US) and Howell s.n. (near Cobarg, Willamette Valley, 7 Apr 1887, US); it is not known if these records represent introductions or remnants of a previously wider distribution. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Draba pennellii is known from White Pine County in east-central Nevada. It is easily distinguished from other white-flowered species in the region by its elongated, many-branched caudices, long styles, usually few-leaved or, rarely, leafless flowering stems, and distinct midvein on fruit valves. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 296. | FNA vol. 7, p. 329. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | Abdra brachycarpa | |
Name authority | Nuttall ex Torrey & A. Gray: Fl. N. Amer. 1: 108. (1838) | Rollins: J. Arnold Arbor. 64: 502. (1983) |
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