Draba incerta |
Draba lonchocarpa |
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whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
lance-fruit Draba, lance-fruit whitlow-grass, lance-pod Draba, lance-pod whitlow-grass, lancefruit Draba whitlow-wort, spear-fruit Draba |
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Habit | Perennials; (cespitose, often pulvinate); caudex branched (dense with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose, sometimes forming mats); caudex branched (covered with persistent leaf bases); often scapose. |
Stems | unbranched, (0.2–)0.4–1.4(–2.1) dm, often pubescent throughout, sometimes glabrous distally, trichomes often simple and 2–5-rayed, 0.1–0.5 mm, (sometimes with mostly subpectinate ones). |
unbranched, (0.1–)0.3–1.1 dm, glabrous throughout or pubescent proximally or throughout, trichomes minutely stalked, 8–12-rayed, (non-crisped), 0.08–0.3 mm. |
Basal leaves | rosulate; petiolate; petiole (0–1 cm), ciliate throughout; blade narrowly oblanceolate to linear, (0.4–)0.6–1.7(–2.5) cm × (1–)1.5–3.5(–5) mm, margins entire, (ciliate, trichomes usually simple, rarely 2-rayed, 0.2–1.1 mm), surfaces usually pubescent with short-stalked, pectinate trichomes, 0.15–0.5 mm, sometimes also with 4–6-rayed ones, (midvein usually obscure abaxially), sometimes glabrous adaxially. |
rosulate; shortly petiolate; petiole (obsolete), margin ciliate proximally, (trichomes soft, simple, 2-rayed, 0.2–0.6 mm); blade oblanceolate to obovate, (0.2–)0.3–1.5 cm × 1–3(–5) mm, margins entire, surfaces pubescent abaxially with short-stalked, stellate, 8–12-rayed, (non-crisped) trichomes, 0.15–0.4 mm, (midvein obscure), adaxially glabrous basally or with simple and long-stalked, branched trichomes. |
Cauline leaves | usually 0 (or 1, as a bract); sessile; blade linear to oblong, margins entire, surfaces pubescent as basal. |
0 or 1(–4); sessile; blade ovate or oblong, margins entire, surfaces pubescent as basal. |
Racemes | 3–14(–30)-flowered, usually ebracteate, rarely proximalmost flowers bracteate, elongated in fruit; rachis not flexuous, glabrous or pubescent as stem. |
3–9-flowered, usually ebracteate, rarely proximalmost 1(–4) flowers bracteate, elongated in fruit; rachis often slightly flexuous (in fruit), glabrous or pubescent as stem. |
Flowers | sepals broadly ovate, 2.5–3.5(–4) mm, pubescent, (trichomes simple and 2- or 3-rayed); petals yellow (fading white), oblanceolate to obovate, 4–6 × 1.5–2.5 mm; anthers ovate, 0.3–0.5 mm. |
sepals ovate, 1.5–2 mm, pubescent, (trichomes simple and short-stalked, 2–5-rayed); petals white, oblanceolate, 2–3.5 × 1–1.5 mm; anthers ovate, 0.2–0.3 mm. |
Fruiting pedicels | ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
ascending, usually straight, rarely curved upward, 2–9(–15) mm, glabrous or pubescent as stem. |
Fruits | broadly ovate to lanceolate, plane, flattened, 5–9(–11) × 2–4 mm; valves glabrous or puberulent, trichomes simple and 2-rayed, 0.05–0.3 mm; ovules 8–16(–20) per ovary; style 0.2–0.9 mm. |
linear to narrowly lanceolate or narrowly oblong, slightly twisted or plane, flattened, 6–15(–18) × 1–2(–3) mm; valves glabrous or sparsely puberulent, trichomes simple and minutely stalked, 2-rayed, 0.1–0.2 mm; ovules 16–24(–28) per ovary; style (0.05–)0.1–0.25(–0.35) mm. |
Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
ovoid, 0.7–1 × 0.5–0.6 mm. |
2n | = 112. |
= 16. |
Draba incerta |
Draba lonchocarpa |
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Phenology | Flowering Jun–Aug. | Flowering Jun–Jul. |
Habitat | Rock outcrops, talus, gravelly areas, tundra | Rocky outcrops and ridges, loose talus, tundra |
Elevation | 0-3300 m (0-10800 ft) | (300-)2800-4000 m ((1000-)9200-13100 ft) |
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
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AK; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC; NT; YT; e Asia (Russian Far East, Siberia)
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Discussion | Draba incerta was shown by G. A. Mulligan (1972) to be sexually reproducing and 14-ploid with x = 8. It is often confused with the apomict D. oligosperma (2n = 32, 64). Draba incerta is readily separated from D. oligosperma by having well-formed (versus abortive) anthers and pollen, stalked (versus sessile) leaf trichomes, and ciliate (versus non-ciliate) basal leaves with obscure (versus prominent) midveins. Although both species have leafless scapes, one often finds a bract adnate to, or subtending, the proximalmost pedicel in D. incerta. Draba incerta is found near sea level in Alaska. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Draba lonchocarpa is a highly variable species within which O. E. Schulz (1927), G. A. Mulligan (1974), and R. C. Rollins (1993) recognized three to five varieties. By contrast, C. L. Hitchcock (1941) united it with D. nivalis and recognized six varieties (see 68. D. nivalis for differences). Some of the infraspecific taxa of D. lonchocarpa are based on trivial characteristics and are listed in the synonymy above without further comment. The most problematic are briefly discussed below. Authors recognizing var. vestita claim that it differs from var. lonchocarpa by having pubescent (versus glabrous) stems and pedicels, 1- or 2-leaved (versus 0 or 1-leaved) scapes, and fruits appressed (versus not appressed) to the rachises. These characteristics do not appear to be strongly correlated. A case in point is the holotype sheet of var. semitonsa, which includes plants with puberulent or glabrous fruits, as well as with pubescent and glabrous stems that are 0–4-leaved. Leafless and densely pubescent scapes are found in Trelease 3913 (MO), whereas completely glabrous, 0–2-leaved stems, and fully appressed fruits are found in Calder 5617a (DAO). Other exceptions can be cited, though the vast majority of the plants examined have leafless, glabrous scapes. An examination of the type collections of var. thompsonii, Thompson 9512 (holotype, UC; isotypes, DS, GH, MO, NY, RSA, US), clearly shows that the taxon usually has oblong to lanceolate fruits 2–3.2 mm wide, as opposed to linear fruits less than 2 mm wide in var. lonchocarpa. Indeed, a casual observation would immediately justify the recognition of var. thompsonii. Both fruit types can be found in plants of the same population (e.g., the RSA isotype) or even on the same plant (e.g., Thompson 10816, MO). Furthermore, fruits to 2.5 mm wide occur sporadically in various parts of the species range. For these reasons, and in the absence of a comprehensive study of the species, we choose to not recognize var. thompsonii at present. Draba lonchocarpa is found at elevations of 300–1200 m in Alaska. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 313. | FNA vol. 7, p. 317. |
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba |
Sibling taxa | ||
Synonyms | D. exalata, D. incerta var. laevicapsula, D. incerta var. peasei, D. laevicapsula, D. peasei | D. nivalis var. elongata, D. lonchocarpa var. denudata, D. lonchocarpa var. exigua, D. lonchocarpa var. semitonsa, D. lonchocarpa var. thompsonii, D. lonchocarpa var. vestita, D. nivalis var. denudata, D. nivalis var. exigua, D. nivalis subsp. lonchocarpa, D. nivalis var. thompsonii |
Name authority | Payson: Amer. J. Bot. 4: 261. (1917) | Rydberg: Mem. New York Bot. Gard. 1: 181. (1900) |
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