Draba alpina |
Draba reptans |
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alpine Draba |
Carolina Draba, Carolina whitlow-grass, Carolina whitlow-mustard, creeping Draba |
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Habit | Perennials; (cespitose); caudex branched (covered with persistent leaves or leaf remains); scapose. | Annuals; scapose or subscapose. |
Stems | unbranched, (0.3–)0.5–1.7(–2.8) dm, pubescent throughout, trichomes simple and 2-rayed, 0.3–0.8 mm, with 3–5-rayed ones, 0.1–0.3 mm. |
(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 | rosulate; petiolate; petiole base (not thickened), ciliate, (trichomes simple, 0.3–1 mm); blade oblanceolate to obovate or lanceolate to oblong, 0.8–3(–4.5) cm × 2.5–6(–9) mm, margins entire, surfaces abaxially pubescent with stalked, 2–4-rayed trichomes, 0.1–0.5 mm, with simple ones (midvein obscure, not thickened), adaxially glabrous or sparsely pubescent with simple and stalked, 2–4-rayed trichomes. |
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 | 0. |
usually 0, rarely 1–3; sessile; blade similar to basal. |
Racemes | 6–18-flowered, ebracteate, considerably elongated in fruit; rachis not flexuous, pubescent as stem. |
(3–)5–12(–16)-flowered, ebracteate, (subumbellate), not elongated in fruit; rachis not flexuous, usually glabrous, rarely sparsely pubescent. |
Flowers | sepals (purplish tinged), narrowly ovate, 2.5–3 mm, pubescent, (trichomes simple and fewer, stalked, 2-rayed); petals bright yellow, narrowly obovate, 3.5–5 × 1.7–2.5 mm; anthers ovate, 0.3–0.4 mm. |
(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. |
Fruiting pedicels | ascending to divaricate-ascending, straight or, sometimes, slightly curved upwards, 4–14(–30) mm, pubescent, trichomes simple and 2–4-rayed. |
horizontal to divaricate-ascending, straight, (1–)2–7(–9) mm, glabrous or glabrate. |
Fruits | elliptic, plane, flattened, 6–10 × 2–3 mm; valves glabrous or glabrescent, trichomes simple, (not confined to replum); ovules 12–24 per ovary; style 0.2–0.3 mm (stigma about as wide as style). |
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 | (pale brown), ovoid, 0.9–1.3 × 0.6–0.9 mm. |
oblong to ovoid, 0.5–0.8 × 0.3–0.5 mm. |
2n | = 80. |
= 16, 30, 32. |
Draba alpina |
Draba reptans |
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Phenology | Flowering Jun–Aug. | Flowering Feb–Jun(-Aug). |
Habitat | Moist tundra and ridges, sand and gravel flats or beaches | Rock outcrops, dry slopes and hillsides, prairies, glades, roadsides, disturbed sites |
Elevation | 0-1000 m (0-3300 ft) | 0-3000 m (0-9800 ft) |
Distribution |
LB; MB; NU; ON; QC; Greenland; Europe (Finland, Norway, Russia, Sweden)
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AL; AR; AZ; CA; CO; GA; IA; ID; IL; KS; MA; MI; MN; MO; MT; NC; ND; NE; NM; NY; OH; OK; OR; PA; SC; SD; TN; TX; UT; WA; WI; WY; AB; BC; MB; ON; SK
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Discussion | The synonymy above includes two North American names overlooked by C. L. Hitchcock (1941) and R. C. Rollins (1993). Draba alpina was broadly delimited by O. E. Schulz (1927) and included 17 varieties, some of which (e.g., corymbosa, oxycarpa, pilosa) are recognized herein as distinct species. The name D. alpina was so misapplied that it was used for any circumpolar or alpine, scapose, yellow-flowered, perennial Draba. Various chromosome numbers (e.g., 2n = 64, 80, 112, 120; S. I. Warwick and I. A. Al-Shehbaz 2006) have been reported for the species. As circumscribed here, it has the narrow distribution outlined above and includes plants with 2n = 80. Reports of the species from Alaska, Canadian Northwest Territories and Yukon, Siberia, eastern Asia, Russian Far East, and the Central Asian republics are either suspect or very unlikely. The entire D. alpina complex (including the above three species, D. glacialis Adams, D. macounii, etc.) is in need of critical molecular, cytological, and morphological study. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 290. | FNA vol. 7, p. 333. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. alpina var. hydeana, D. alpina var. inflatisiliqua | Arabis reptans, D. caroliniana, D. caroliniana var. dolichocarpa, D. caroliniana var. hunteri, D. caroliniana var. micrantha, D. caroliniana subsp. stellifera, D. caroliniana var. umbellata, D. coloradensis, D. hispidula, D. micrantha, D. reptans var. micrantha, D. reptans subsp. stellifera, D. reptans var. stellifera, D. umbellata, Tomostima caroliniana, Tomostima hispidula, Tomostima micrantha |
Name authority | Linnaeus: Sp. Pl. 2: 642. (1753) | (Lamarck) Fernald: Rhodora 36: 368. (1934) |
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