Draba exunguiculata |
Draba micropetala |
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clawless Draba |
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Habit | Perennials; (densely cespitose); caudex branched (covered with persistent, somewhat thickened, dry petioles); not scapose. | Perennials; caudex branched (with persistent leaf remains); scapose. |
Stems | unbranched, 0.15–0.7 dm, glabrous throughout or sparsely pubescent, trichomes simple, 0.3–0.9 mm. |
unbranched, (0.05–)0.15–0.7(–1.1) dm, pubescent throughout, sometimes sparsely so distally, trichomes stalked, 2–4-rayed, and simple, 0.05–0.6 mm. |
Basal leaves | rosulate; petiolate; petiole ciliate, (trichomes simple, 0.3–1.1 mm); blade linear to linear-oblanceolate, (0.5–)0.8–2(–2.5) cm × 1–3 mm, margins entire, (pubescent as petiole), surfaces abaxially sparsely pubescent with simple and stalked, 2- or 3-rayed trichomes, 0.1–0.4 mm, adaxially glabrous or subapically sparsely pubescent with simple trichomes. |
(not imbricate); rosulate; petiolate; petiole (base thickened), margin ciliate, (trichomes coarse, simple and 2-rayed, 0.3–1.3 mm); blade broadly oblanceolate to broadly obovate, 0.6–2 cm × 4–12 mm, margins entire, (apex obtuse to rounded, trichomes multibranched, subcruciform), surfaces pubescent abaxially with stalked, 2–4-rayed and, rarely, simple trichomes, 0.1–0.6 mm, adaxially glabrous or with mostly simple trichomes. |
Cauline leaves | 1–4; sessile; blade linear to linear-oblanceolate, margins entire, surfaces pubescent as basal. |
0. |
Racemes | 4–13(–20)-flowered, ebracteate, elongated in fruit; rachis not flexuous, usually glabrous, rarely sparsely pubescent, trichomes simple, to 1 mm. |
2–7(–10)-flowered, ebracteate, often elongated in fruit; rachis often flexuous, pubescent as stem. |
Flowers | sepals ovate, 2–2.5 mm, pubescent, (trichomes simple); petals (erect), yellow, obovate, 2–2.5(–3) × 1.5–2 mm, (not clawed); anthers oblong, 0.6–0.9 mm. |
sepals oblong, 1.8–2.5 mm, pubescent, (trichomes simple, with short-stalked, 2-rayed ones); petals pale yellow, narrowly spatulate or oblanceolate, 2–3 × (0.7–)1–1.5 mm; anthers ovate, 0.3–0.4 mm. |
Fruiting pedicels | divaricate-ascending, straight or slightly curved upward, 1–6 mm, usually glabrous, rarely with few, simple trichomes. |
divaricate to ascending, straight, 1–3(–4) mm, pubescent as stem. |
Fruits | lanceolate to oblong-lanceolate, plane, flattened, 5–13 × 1.5–3 mm; valves glabrous; ovules 20–24 per ovary; style 0.3–1 mm. |
elliptic-ovate, plane, slightly flattened, 5–10 × 2–3.2 mm; valves often densely pubescent, trichomes simple and spurred, 0.1–0.5 mm; ovules (16–)18–28 per ovary; style 0.05–0.3 mm (stigma about as wide as style). |
Seeds | ovoid, 1–1.3 × 0.6–0.8 mm. |
oblong, 1–1.1 × 0.5–0.6 mm. |
2n | = 56 ± 5. |
= 48. |
Draba exunguiculata |
Draba micropetala |
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Phenology | Flowering Jul–Aug. | Flowering Jun–Jul. |
Habitat | Open knolls, talus, gravelly alpine slopes, rocky alpine tundra | Meadows, mesic tundra, swales, gravelly soils |
Elevation | 3600-4300 m (11800-14100 ft) | 0-900 m (0-3000 ft) |
Distribution |
CO |
AK; NT; NU; Greenland; Europe (Norway [Spitsbergen]); e Asia (Russian Far East, Siberia) |
Discussion | Of conservation concern. Draba exunguiculata occupies alpine areas of Clear Creek, El Paso, Grand, and Summit counties in central Colorado. Draba grayana is found in the same general area; both species are apomicts that occasionally grow sympatrically. Draba exunguiculata is easily distinguished from D. grayana by having stems and fruiting pedicels glabrous or sparsely pubescent with simple trichomes (versus moderately to densely pubescent with simple and 2- or 3-rayed trichomes), and by having erect, non-clawed petals, 2–3 mm and slightly longer than sepals (versus flared, clawed petals 3–4.5 mm and nearly twice as long as sepals). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Draba micropetala, which was not listed by C. L. Hitchcock (1941) or R. C. Rollins (1993), is frequently confused with the closely related tetraploid (2n = 32) D. pauciflora. It is distinguished from the latter by having elongated (versus congested) fruiting racemes, narrower [2–3.2 versus (3–)3.5–5 mm] and elliptic-ovate (versus obovate) fruits, more [(16–)18–28 versus 8–16(–20)] seeds per fruit, and obtuse to rounded (versus subacute to acute) leaf apices with multibranched, subcruciform (versus simple and/or 2-branched) trichomes. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 306. | FNA vol. 7, p. 319. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. chrysantha var. exunguiculata, D. chrysantha | D. alpina var. micropetala, D. oblongata subsp. minuta, D. pauciflora var. micropetala |
Name authority | (O. E. Schulz) C. L. Hitchcock: Revis. Drabas W. N. Amer., 46. (1941) | Hooker: in W. E. Parry, App. Parry J. Sec. Voy., 385. (1825) |
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