Draba brachycarpa |
Draba trichocarpa |
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short-pod whitlowgrass, shortfruit Draba, shortpod Draba |
stanley creek Draba |
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Habit | Annuals; not scapose. | Perennials; (cespitose, densely pulvinate); caudex branched (covered with persistent leaves, branches sometimes terminating in sterile rosettes); 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, 0.07–0.35 dm, pubescent throughout, trichomes (soft), stalked, subdendritic, (somewhat crisped), 0.1–0.5 mm, (simple ones absent). |
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. |
(densely imbricate); rosulate; sessile; blade oblong to obovate, 0.2–0.4 cm × 0.5–1.5 mm, margins entire, (ciliate, trichomes simple and branched, subdendritic, or spurred, 0.3–0.8 mm), surfaces sparsely pubescent, abaxially with stalked, 4–6-rayed stellate trichomes, 0.1–0.4 mm, adaxially with simple and 4–6-rayed trichomes, mainly on distal 1/2. |
Cauline leaves | (4–)6–11; sessile; blade lanceolate to oblong or linear, margins entire, surfaces pubescent as basal. |
0 (or 1); sessile; blade similar to basal. |
Racemes | (main branch) (20–)25–65(–74)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
2–9-flowered, ebracteate, slightly 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, 2–3 mm, pubescent, (trichomes short-stalked); petal color unknown, broadly obovate, 2–4 × 2–2.5 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, 1–4.5 mm, pubescent as stem. |
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. |
ovoid, plane, slightly inflated basally, flattened distally, 2–6 × 2–3.5 mm; valves densely pubescent, trichomes 4-rayed, 0.1–0.4 mm, (often some rays spurred or branched); ovules 4–10 per ovary; style 0.3–0.7 mm. |
Seeds | (winged), ovoid, 0.5–0.7 × 0.4–0.5 mm. |
oblong, 1.4–2 × 0.8–1.2 mm. |
2n | = 16. |
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Draba brachycarpa |
Draba trichocarpa |
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Phenology | Flowering Feb–May. | Flowering Jun–Jul. |
Habitat | Open woods, cedar glades, pastures and lawns, roadsides, disturbed sites | Gravelly metamorphic soil at ecotone between sagebrush steppe and open conifer forests |
Elevation | 0-300 m (0-1000 ft) | ca. 2000 m (ca. 6600 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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ID |
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 trichocarpa is an apomictic polyploid that appears to be closely related to D. novolympica. It is readily distinguished from that species by the primarily dendritic trichomes (and absence of simple trichomes) on the stems, pedicels, and fruits. Draba trichocarpa is known from the Stanley Basin of central Idaho (Custer County). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 296. | FNA vol. 7, p. 344. |
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: Contr. Gray Herb. 214: 4. (1984) |
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