Draba ruaxes |
Draba weberi |
|
---|---|---|
coast mountain Draba, coast mountain whitlow-grass, coast mountain whitlow-grass Draba, Rainier Draba |
weber's Draba |
|
Habit | Perennials; (cespitose, forming tufts); caudex branched (with persistent leaf bases, branches some terminating in sterile rosettes); scapose. | Perennials; (cespitose); caudex branched (covered with persistent, somewhat thickened, petioles); not scapose. |
Stems | unbranched, 0.2–0.6(–0.8) dm, often pubescent throughout, sometimes glabrate distally, trichomes simple, 0.4–1 mm, and 2–4-rayed, 0.1–0.4 mm. |
unbranched, 0.2–0.6(–1) dm, glabrous or sparsely pubescent throughout, trichomes simple, sessile or subsessile, 2- or 3-rayed, 0.2–0.6 mm. |
Basal leaves | rosulate; subsessile; petiole base and margin ciliate, (trichomes simple, 0.4–1.4 mm); blade oblanceolate to obovate or suborbicular, 0.3–1 cm × 2–4.5 mm, margins entire, surfaces pubescent, abaxially with stalked, 2–10-rayed, stellate trichomes, 0.2–0.8 mm, adaxially with simple trichomes, 0.4–1 mm, sometimes with smaller, 2–4-rayed ones, (midvein obscure). |
rosulate; petiolate; petiole margin ciliate, (trichomes simple, 0.2–0.6 mm); blade linear-oblanceolate, 0.4–1.5 cm × 0.8–1.7 mm, margins entire, (pubescent as petiole), surfaces pubescent abaxially with (appressed), simple, subsessile or sessile, 2–4-rayed trichomes, 0.1–0.4 mm, glabrous or subapically sparsely pubescent adaxially with simple trichomes. |
Cauline leaves | 0. |
1–3; sessile; blade linear-oblong, margins entire, surfaces pubescent as basal. |
Racemes | (2–)4–10(–14)-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent as stem or glabrous. |
5–15-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous or pubescent as stem. |
Flowers | sepals ovate, 2–3 mm, pubescent, (trichomes simple with fewer, 2-rayed ones); petals bright yellow, obovate, 4–6 × 2–3.5 mm; anthers oblong, 0.4–0.5 mm. |
sepals ovate, 1.5–2 mm, pubescent, (trichomes simple and 2-rayed); petals yellow, spatulate, 3–4 × 1.2–1.8 mm, (flared, clawed); anthers ovate, 0.3–0.4 mm. |
Fruiting pedicels | ascending to divaricate-ascending, straight or slightly curved upward, 3–7(–9) mm, pubescent or glabrous, trichomes simple and 2–4-rayed. |
divaricate-ascending, straight, 2–6 mm, glabrous or sparsely pubescent as stem. |
Fruits | elliptic to lanceolate or ovate to suborbicular, plane, flattened, 4–8(–10) × 3–4.5 mm; valves puberulent, trichomes simple with fewer 2-rayed ones, 0.1–0.35 mm; ovules 12–16 per ovary; style 0.5–0.9(–1.1) mm. |
ovate, plane, flattened, 4–8 × 2–3 mm; valves glabrous; ovules 16–18 per ovary; style 0.2–0.3 mm. |
Seeds | oblong, 1.5–2 × 1–1.3 mm. |
ovoid, 1–1.2 × 0.6–0.7 mm. |
2n | = 72. |
|
Draba ruaxes |
Draba weberi |
|
Phenology | Flowering Jun–Jul. | Flowering Jun–Jul. |
Habitat | Rock outcrops, talus slopes, ridges, alpine summits | Rock crevices along streamlets near timberline |
Elevation | 500-2400 m (1600-7900 ft) | ca. 3500 m (ca. 11500 ft) |
Distribution |
AK; WA; AB; BC; YT
|
CO |
Discussion | C. L. Hitchcock (1941) treated Draba ruaxes as a variety of D. ventosa; as demonstrated by G. A. Mulligan (1971b), the two are quite distinct. Draba ruaxes is an outcrossing hexaploid with well-formed anthers and pollen, and abundant, simple trichomes on leaves, stems, sepals, and fruits. By contrast, D. ventosa is an apomictic triploid with abortive anthers and/or pollen, and no simple trichomes anywhere on the plant. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Draba weberi is an apomictic species allied to D. exunguiculata, D. grayana, and D. streptobrachia. From those, it is distinguished by having ovate fruits, clawed petals, and sessile, 2–4-rayed trichomes with untwisted rays often appressed to leaf and stem surfaces. Draba weberi is known from near North Star Peak in central Colorado (Summit County). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 334. | FNA vol. 7, p. 346. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. ventosa var. ruaxes | |
Name authority | Payson & H. St. John: Proc. Biol. Soc. Wash. 43: 117. (1930) | R. A. Price & Rollins: Harvard Pap. Bot. 1(3): 75, fig. 3. (1991) |
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