Draba globosa |
Draba brachystylis |
|
---|---|---|
beavertip Draba, rockcress Draba, round-fruit Draba |
shortstyle Draba |
|
Habit | Perennials; (cespitose, pulvinate); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. | Annuals or perennials; (short-lived); caudex often simple (poorly developed); not scapose. |
Stems | unbranched, 0.1–0.5 dm, glabrous. |
unbranched or branched, 0.6–3(–3.7) dm, pubescent throughout, trichomes simple, 0.4–0.9 mm, and 2–4-rayed, 0.05–0.4 mm. |
Basal leaves | rosulate; sessile; blade (not fleshy), narrowly oblanceolate or lanceolate to linear, (0.2–)0.3–0.8 cm × 0.5–1.6(–2) mm, margins entire (ciliate, trichomes simple, 0.1–0.8 mm, apex acute, trichomes usually longer), surfaces glabrous, (midvein obscure abaxially). |
rosulate; subsessile; petiole base ciliate, (trichomes simple, 0.3–0.9 mm); blade oblanceolate, 1–3.5 cm × 4–7(–12) mm, margins entire or denticulate, surfaces pubescent, abaxially with stalked, (2–)4-rayed trichomes, 0.1–0.5 mm, adaxially with simple trichomes, 0.2–0.6 mm, with smaller, 2–4-rayed ones. |
Cauline leaves | 0. |
(1 or) 2–6(–8); sessile; blade lanceolate or oblanceolate to ovate, margins entire or denticulate, surfaces pubescent as basal. |
Racemes | 2–5(–7)-flowered, ebracteate, slightly elongated in fruit; rachis not flexuous, glabrous. |
(5–)10–35(–47)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
Flowers | sepals (persistent to near fruit maturity), ovate to broadly oblong, 2–3 mm, glabrous; petals white to pale yellow, obovate, 2.5–4 × 1.2–2 mm; anthers oblong, 0.4–0.6 mm. |
sepals ovate, 2–2.7 mm, pubescent, (trichomes simple and short-stalked, 2-rayed); petals pale yellow (fading white), oblanceolate, 2.5–3.7 × 0.9–1.2 mm; anthers ovate, 0.2–0.3 mm. |
Fruiting pedicels | divaricate-ascending, straight or slightly curved, 2–6 mm, glabrous. |
divaricate-ascending, straight or only slightly curved upward, (1.5–)3–8(–10) mm, pubescent throughout, trichomes simple and stalked, 2–4-rayed. |
Fruits | ovate, plane, flattened, 4.5–8 × 2.5–4 mm; valves (distinctly veined), glabrous; ovules 8–16 per ovary; style (0.1–)0.2–0.6 mm. |
narrowly elliptic to lanceolate, plane, flattened, (7–)10–16(–19) × 2–3.5 mm; valves pubescent, trichomes simple, spurred, and short-stalked, 2-rayed, 0.05–0.2(–0.3) mm; ovules 20–36(–42) per ovary; style 0.2–0.6(–0.8) mm. |
Seeds | oblong, 1.1–1.4 × 0.8–1 mm. |
oblong, 0.9–1.3 × 0.6–0.7 mm. |
2n | = 44. |
|
Draba globosa |
Draba brachystylis |
|
Phenology | Flowering Jun–Aug. | Flowering Jun–Jul. |
Habitat | Ridges, talus, alpine tundra and meadows | Fir and aspen communities, moist areas on rocky slopes |
Elevation | 2700-3900 m (8900-12800 ft) | 1700-3000 m (5600-9800 ft) |
Distribution |
ID; MT; UT; WY
|
UT |
Discussion | Draba globosa is an apomictic species closely related to D. burkei (M. D. Windham, unpubl.). Though often treated as a variety of D. densifolia, it is morphologically and phyletically distinct from that species. Both R. C. Rollins (1993) and N. H. Holmgren (2005b) indicated that the species occurs in Colorado, but we have not seen material for that state. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Based on morphological and chromosomal data (L. Allphin and M. D. Windham, unpubl.), Draba brachystylis is hypothesized to be an allopolyploid derived through hybridization between D. albertina and D. santaquinensis. It is known to us only from Cache, Duchesne, Juab, Salt Lake, and Utah counties. C. L. Hitchcock (1941) indicated that the species grows in the Charleston Mountains of Clark County, Nevada, but we have not seen unequivocal material of it from that area. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 308. | FNA vol. 7, p. 297. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. apiculata, D. densifolia var. apiculata, D. densifolia var. decipiens, D. densifolia var. globosa | |
Name authority | Payson: Amer. J. Bot. 4: 257. (1917) | Rydberg: Bull. Torrey Bot. Club 29: 240. (1902) |
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