Draba aurea |
Draba ventosa |
|
---|---|---|
golden Draba, golden Draba whitlow-grass, golden whitlow-grass, twisted-pod Draba |
wind river Draba, wind river whitlow-grass |
|
Habit | Perennials; (not cespitose); caudex simple or branched; not scapose. | Perennials; (cespitose); caudex branched (covered with persistent leaves, branches creeping, sometimes terminating in sterile rosettes); scapose. |
Stems | sometimes branched distally, (0.5–) 1–3.5(–5.2) dm, pubescent throughout, trichomes simple (non-crisped), 0.4–1.3 mm, and 3–6-rayed ones, 0.1–0.5 mm. |
unbranched, (0.1–)0.2–0.4(–0.6) dm, densely pubescent throughout, trichomes 2–6-rayed, 0.1–0.6 mm. |
Basal leaves | rosulate; petiolate; petiole (distinct or obscure) ciliate, (trichomes simple, to 0.8 mm); blade oblanceolate to obovate, (0.4–)1–3.7(–5) cm × (1–)2–7(–10) mm, margins entire or denticulate, surfaces pubescent, trichomes stalked, (2–)4–7 (or 8)-rayed, 0.2–0.5(–0.6) mm. |
(imbricate); rosulate; subsessile; petiole base and margin not ciliate; blade obovate to oblanceolate, (0.4–)0.5–1 cm × 1.5–4.5 mm, margins entire, surfaces densely pubescent with stalked, 2–6-rayed trichomes, (0.1–)0.2–0.9 mm. |
Cauline leaves | 5–20(–26); sessile; blade oblong to lanceolate or ovate, margins entire or dentate, surfaces pubescent as basal, sometimes adaxially with simple trichomes. |
0. |
Racemes | (10–)18–52(–72)-flowered, usually bracteate on proximalmost 1–12(–17) flowers, rarely ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem. |
5–10(–16)-flowered, ebracteate, slightly elongated in fruit; rachis not flexuous, densely pubescent as stem. |
Flowers | sepals (green or yellowish), oblong, 2.2–3 mm, pubescent, (trichomes simple and branched); petals yellow, oblanceolate, 3.5–5 × 1.5–2.5 mm; anthers ovate, 0.4–0.5 mm. |
sepals broadly ovate, 2–2.5 mm, pubescent, (trichomes short-stalked, 2–6-rayed); petals yellow, obovate, 3.5–5.5 × 1.5–3 mm; anthers oblong, 0.5–0.6 mm. |
Fruiting pedicels | divaricate-ascending to ascending or suberect, straight, 3–13(–20) mm, pubescent as stem. |
horizontal to divaricate-ascending, straight or slightly curved upward, 2–7(–9) mm, densely pubescent, trichomes 2–6-rayed, (0.1–0.6 mm). |
Fruits | (often subappressed to rachis), lanceolate to linear-lanceolate or narrowly oblong, slightly twisted or plane, flattened, (6–)9–14(–17) × 2–3.5 mm; valves pubescent, trichomes simple and short-stalked, 2–4-rayed, 0.05–0.3 mm; ovules 28–38(–44) per ovary; style 0.5–1.2(–1.5) mm. |
suborbicular to broadly ovate, plane, inflated basally, flattened distally, 4–7.5(–9) × 3.5–5 mm; valves densely pubescent, trichomes short-stalked, 2–6-rayed, 0.15–0.5 mm; ovules 8–12 per ovary; style (0.5–)0.7–1.4 mm. |
Seeds | oblong, 0.9–1.3 × 0.5–0.7 mm. |
oblong, 1.4–1.9 × 0.9–1.2 mm. |
2n | = 74. |
= 36. |
Draba aurea |
Draba ventosa |
|
Phenology | Flowering Jun–Aug. | Flowering Jul–Aug. |
Habitat | Rock outcrops, talus, damp gullies and meadows, subalpine conifer woodlands, alpine slopes and turf, tundra, road banks, river gravel | Talus slopes and alpine tundra |
Elevation | (0-)700-4200 m ((0-)2300-13800 ft) | 2000-4000 m (6600-13100 ft) |
Distribution |
AK; AZ; CO; ID; MT; NM; NV; SD; UT; WA; WY; AB; BC; MB; NF; NT; NU; ON; QC; SK; YT; Greenland
|
CO; UT; WY; AB; BC; YT |
Discussion | Draba aurea is extremely variable in plant size, number of cauline leaves, number of bracteate flowers, style length, and fruit size, shape, orientation, twisting, and indumentum. Much of the variation in the number of bracts, style length, fruit twisting, and growth habit occurs in Greenland, where the type specimen was collected and where the species is found near sea level. The highly deviant chromosome counts (e.g., 2n = 40 + 1, 64, 82) listed by R. C. Rollins (1993) and S. I. Warwick and I. A. Al-Shehbaz (2006) are mostly unvouchered and have to be disregarded; counts of 2n = ca. 80 have been re-assigned to Draba glabella. Published (G. A. Mulligan 2002) and unpublished counts made by Mulligan and M. D. Windham from Alaska, British Columbia, Colorado, Quebec, Utah, and Yukon indicate that the most common chromosome number of D. aurea is 2n = 74 (or 72). This suggests that the species is an allopolyploid (hexaploid or higher), incorporating genomes from both euploid and aneuploid lineages (M. A. Beilstein and Windham 2003). Detailed cytological and molecular studies are much needed to fully understand this widely distributed and highly variable species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
G. A. Mulligan (1971b) first reported apomixis in Draba ventosa based on studies of Canadian populations. This has now been confirmed in one of the southernmost populations (Duchesne County, Utah; M. D. Windham, unpubl.) as well. The species is easily overlooked and the large geographic gap between the Canadian and United States populations is likely to be narrowed or eliminated by additional collecting in western Montana. The limits of this species were expanded by C. L. Hitchcock (1941) to include D. ruaxes, but there are clear differences between them that support their recognition as distinct species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 294. | FNA vol. 7, p. 344. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. aurea var. aureiformis, D. aurea var. leiocarpa, D. aurea var. luteola, D. aureiformis, D. aureiformis var. leiocarpa, D. bakeri, D. decumbens, D. henneana var. maccallae, D. luteola, D. luteola var. minganensis, D. maccallae, D. minganensis, D. surculifera, D. uber | |
Name authority | Vahl ex Hornemann: Fors. Oecon. Plantel. ed. 2, 599. (1806) | A. Gray: Amer. Naturalist 8: 212. (1874) |
Web links |