Draba stenoloba |
Draba verna |
|
---|---|---|
Alaska Draba, Alaska whitlow-grass |
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 |
|
Habit | Biennials or perennials; (short-lived, not cespitose); caudex simple (not fleshy); scapose. | Annuals; scapose. |
Stems | often unbranched, (0.2–)0.4–3(–3.4) dm, pubescent proximally, usually glabrous distally, rarely sparsely pubescent, trichomes short-stalked, 2–4-rayed, 0.1–0.4(–0.5) 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 | rosulate; petiole (obscure), margin ciliate, (trichomes simple, 0.2–0.4 mm); blade oblanceolate to obovate, 0.4–2.6(–3.1) cm × 1.5–7(–10) mm, margins entire or denticulate, (ciliate as petiole), surfaces pubescent, abaxially with short-stalked, 3- or 4-rayed trichomes, 0.1–0.5 mm, adaxially with simple and stalked, 2–4-rayed trichomes, 0.1–0.5 mm. |
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 or) 1 or 2 (3 or 4); sessile; blade elliptic to lanceolate or ovate, margins toothed, surfaces pubescent, abaxially with short-stalked 3- or 4-rayed trichomes, adaxially with simple and short-stalked, 2–4-rayed trichomes. |
0. |
Racemes | (2–)4–10(–15)-flowered, ebracteate, elongated in fruit; rachis not flexuous, usually glabrous, rarely sparsely pubescent. |
4–20(–30)-flowered, ebracteate, usually considerably elongated in fruit; rachis usually flexuous, glabrous. |
Flowers | (chasmogamous, petaliferous); sepals (green or purplish), oblong, 1.5–2.5 mm, glabrous or pubescent, (trichomes simple); petals yellow, oblanceolate, 2.5–3.5 × 0.6–1 mm; anthers ovate, 0.25–0.4 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 | horizontal to divaricate-ascending, straight, 3–14(–19) mm (subequaling or shorter than fruit), usually glabrous, rarely pubescent, trichomes 2–4-rayed. |
divaricate to ascending, straight or slightly curved upward, (2–)5–20(–35) mm, glabrous. |
Fruits | linear or, rarely, linear-elliptic, plane, flattened, (8–)10–17(–20) × 1.5–2 mm; valves usually glabrous, rarely sparsely puberulent, trichomes simple; ovules 24–36 per ovary; style 0.01–0.15 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 | ovoid, 0.9–1 × 0.5–0.6 mm. |
ovoid (slightly flattened), 0.3–0.6(–0.8) × 0.2–0.4 mm. |
2n | = 40. |
= 14, 16, 20, 24, 28, 30, 32, 34, 36, 38, 40, 52, 54, 58, 60, 64. |
Draba stenoloba |
Draba verna |
|
Phenology | Flowering Jun–Jul. | Flowering Feb–May. |
Habitat | Grassy knolls, glacial moraines and creek banks, mesic meadows, alpine thickets | Cedar glades, lawns, fields, pastures, waste places, grassy hillsides, disturbed sites, roadsides |
Elevation | 600-2300 m (2000-7500 ft) | 0-2500 m (0-8200 ft) |
Distribution |
AK; OR; WA; AB; BC; YT
|
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]
|
Discussion | Draba stenoloba is occasionally confused with D. albertina, but is easily recognized by having exclusively 2–4-rayed (versus mostly simple) trichomes on stems proximally. It is rarely encountered and apparently confined to the Pacific Northwest. In contrast, D. albertina is common and widespread in the mountains of western North America. (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. 340. | FNA vol. 7, p. 345. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. acinacis, D. hirta var. siliquosa, D. macouniana, D. nemorosa var. stenoloba, D. nitida var. praelonga, D. oligantha, D. stenoloba var. oligantha | 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 | Ledebour: Fl. Ross. 1: 154. (1841) | Linnaeus: Sp. Pl. 2: 642. (1753) |
Web links |
|
|