Draba hitchcockii |
Draba verna |
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lost river Draba |
common Draba, common whitlow-grass, early witlow grass, nailwort, shadflower, spring Draba, spring whitlow-grass, spring whitlow-mustard, vernal whitlow grass, whitlow grass, whitlow wort |
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Habit | Perennials; (densely cespitose); caudex branched (densely covered with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. | Annuals; scapose. |
Stems | unbranched, (0.1–)0.3–1(–1.3) dm, hirsute throughout, trichomes simple, 0.4–1 mm, and 2–4-rayed, 0.1–0.6 mm. |
(few to many from base), unbranched, (0.2–)0.5–2(–3) dm, pubescent proximally, glabrous distally, trichomes simple and 2(–4)-rayed, 0.1–0.4 mm. |
Basal leaves | (densely imbricate); rosulate; sessile; blade narrowly oblanceolate to oblong-linear, 0.3–1.2(–1.5) cm × 1–2 mm, margins entire, (ciliate, trichomes simple, 0.3–1.2 mm), surfaces pubescent abaxially with stalked, 2–4-rayed trichomes, 0.08–0.45 mm, (midvein obscure), adaxially glabrous proximally, sparsely pubescent distally with mostly simple trichomes. |
rosulate; petiolate; blade obovate, spatulate, oblanceolate, lanceolate, oblong, or, rarely, linear, 0.2–1.8(–3) cm × (0.5–)1–5(–10) mm, margins entire or 1–5-toothed on each side, surfaces pubescent with simple or stalked, 2–4-rayed trichomes, 0.1–0.5 mm. |
Cauline leaves | 0. |
0. |
Racemes | 4–15-flowered, ebracteate, elongated in fruit; rachis not flexuous, hirsute as stem. |
4–20(–30)-flowered, ebracteate, usually considerably elongated in fruit; rachis usually flexuous, glabrous. |
Flowers | sepals oblong, 2.5–3.5 mm, hirsute, (trichomes simple and stalked, 2–4-rayed); petals white, obovate, 5–6.5 × 2–3.5 mm; anthers ovate, 0.5–0.6 mm. |
sepals (green or purplish), oblong, 1–2.5 mm, glabrescent or pubescent, (trichomes simple or 2-rayed); petals white, deeply 2-fid, (1.5–)2–4.5(–6) × 1–2 mm; anthers ovate, 0.2–0.4 mm. |
Fruiting pedicels | ascending, straight, (2–)4–13(–18) mm, hirsute as stem. |
divaricate to ascending, straight or slightly curved upward, (2–)5–20(–35) mm, glabrous. |
Fruits | ovate to broadly oblong or elliptic, plane, flattened, (3–)4–7(–10) × (2.5–)3.5–5 mm; valves pubescent, trichomes simple and short-stalked, 2(–4)-rayed, 0.06–0.5 mm; ovules 8–12 per ovary; style (0.8–)1–1.7(–2) mm. |
obovate, oblanceolate, lanceolate, elliptic, oblong, or linear, plane, flattened, (2.5–)4–9(–12) × 1.5–2.5(–3.5) mm; valves glabrous; ovules (20–)32–70(–84) per ovary; style 0.02–0.2 mm. |
Seeds | oblong, 1.4–1.8 × 0.8–1 mm. |
ovoid (slightly flattened), 0.3–0.6(–0.8) × 0.2–0.4 mm. |
2n | = 54. |
= 14, 16, 20, 24, 28, 30, 32, 34, 36, 38, 40, 52, 54, 58, 60, 64. |
Draba hitchcockii |
Draba verna |
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Phenology | Flowering May–Jun. | Flowering Feb–May. |
Habitat | Limestone outcrops and gravelly soil | Cedar glades, lawns, fields, pastures, waste places, grassy hillsides, disturbed sites, roadsides |
Elevation | 1800-2200 m (5900-7200 ft) | 0-2500 m (0-8200 ft) |
Distribution |
ID |
AL; AR; CA; CT; DC; DE; GA; IA; ID; IL; IN; KY; MA; MD; ME; MI; MO; MS; MT; NC; NH; NJ; NV; NY; OH; OR; PA; RI; SC; TN; UT; VA; VT; WA; WV; WY; AB; BC; NB; ON; QC; Europe; Asia; nw Africa [Introduced in North America; introduced also in Central America, South America, Australia]
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Discussion | Draba hitchcockii is known from the Lost River Range in Butte and Custer counties. Based on morphological and chromosomal evidence, M. D. Windham (2004) suggested that it may be an allopolyploid resulting from hybridization between D. oreibata and D. paysonii. Draba hitchcockii is superficially similar to D. jaegeri, a taxon known from the Charleston Mountains of Clark County, Nevada. Both are cespitose perennials with relatively large, white flowers and a chromosome number (2n = 54) otherwise unknown in Draba (Windham). Features distinguishing these two taxa are provided in the discussion of 51. D. jaegeri. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Draba verna represents a highly variable and taxonomically difficult complex within which species, subspecies, varieties, and forms have been named (O. E. Schulz 1927); only those synonyms pertaining to North America are listed above. Most of the taxonomic difficulties are the results of disploidy, autogamy, and hybridization. The morphological extremes are connected by intermediate forms in every conceivable character. Furthermore, there appears to be no correlation between morphology, cytology, geography, and ecology to support the division of this complex into meaningful taxa. A complex cytological picture was presented by Ø. Winge (1940), including the highest count of 2n = 94, which has not been confirmed by subsequent botanists. Erophila vulgaris de Candolle is an illegitimate name for Draba verna. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 311. | FNA vol. 7, p. 345. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. boerhaavii, D. praecox, D. verna var. aestivalis, D. verna var. boerhaavii, Erophila boerhaavii, Erophila krockeri, Erophila praecox, Erophila verna, Erophila verna subsp. praecox | |
Name authority | Rollins: J. Arnold Arbor. 64: 500. (1983) | Linnaeus: Sp. Pl. 2: 642. (1753) |
Web links |
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