Draba trichocarpa |
Draba zionensis |
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stanley creek Draba |
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Habit | Perennials; (cespitose, densely pulvinate); caudex branched (covered with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose); caudex branched (with persistent leaf bases, branches sometimes terminating in sterile rosettes); scapose. |
Stems | unbranched, 0.07–0.35 dm, pubescent throughout, trichomes (soft), stalked, subdendritic, (somewhat crisped), 0.1–0.5 mm, (simple ones absent). |
unbranched, 0.5–1.5(–1.8) dm, usually sparsely pubescent proximally, usually glabrous distally, rarely throughout, trichomes simple, 0.3–0.8 mm, often with smaller, 2–4-rayed ones. |
Basal leaves | (densely imbricate); rosulate; sessile; blade oblong to obovate, 0.2–0.4 cm × 0.5–1.5 mm, margins entire, (ciliate, trichomes simple and branched, subdendritic, or spurred, 0.3–0.8 mm), surfaces sparsely pubescent, abaxially with stalked, 4–6-rayed stellate trichomes, 0.1–0.4 mm, adaxially with simple and 4–6-rayed trichomes, mainly on distal 1/2. |
rosulate; shortly petiolate; petiole base sometimes ciliate (margin not ciliate, trichomes simple and 2-rayed, 0.2–0.5 mm); blade spatulate to obovate, 0.7–3.5 cm × 3–10(–12) mm, margins usually entire, rarely obscurely dentate (near apex), surfaces sparsely pubescent with stalked, (2–)4 (or 5)-rayed trichomes, 0.05–0.5 mm, (midvein obscure). |
Cauline leaves | 0 (or 1); sessile; blade similar to basal. |
0. |
Racemes | 2–9-flowered, ebracteate, slightly elongated in fruit; rachis not flexuous, pubescent as stem. |
14–36-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous. |
Flowers | sepals ovate, 2–3 mm, pubescent, (trichomes short-stalked); petal color unknown, broadly obovate, 2–4 × 2–2.5 mm; anthers oblong, 0.5–0.6 mm. |
sepals ovate, 2–3 mm, glabrous or sparsely pubescent, (trichomes simple and short-stalked, 2–4-rayed); petals orange-yellow (fading pale yellow), broadly spatulate to subovate, 5–6 × 1.8–2.8 mm; anthers ovate, 0.4–0.5 mm. |
Fruiting pedicels | divaricate-ascending to ascending, straight, 1–4.5 mm, pubescent as stem. |
ascending to divaricate-ascending, straight, (not expanded basally), (4–)5–12(–15) mm, glabrous. |
Fruits | ovoid, plane, slightly inflated basally, flattened distally, 2–6 × 2–3.5 mm; valves densely pubescent, trichomes 4-rayed, 0.1–0.4 mm, (often some rays spurred or branched); ovules 4–10 per ovary; style 0.3–0.7 mm. |
lanceolate to linear-lanceolate or ovate, plane (not curved), flattened, 6–12(–17) × 2–3 mm; valves glabrous; ovules 12–20 per ovary; style 0.4–1 mm. |
Seeds | oblong, 1.4–2 × 0.8–1.2 mm. |
oblong, 1–1.3 × 0.6–0.8 mm. |
2n | = 26. |
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Draba trichocarpa |
Draba zionensis |
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Phenology | Flowering Jun–Jul. | Flowering Mar–May. |
Habitat | Gravelly metamorphic soil at ecotone between sagebrush steppe and open conifer forests | Sandstone (rarely limestone) rock outcrops and sandy slopes in pinyon-juniper or pine communities |
Elevation | ca. 2000 m (ca. 6600 ft) | 1000-2500 m (3300-8200 ft) |
Distribution |
ID |
UT |
Discussion | Of conservation concern. Draba trichocarpa is an apomictic polyploid that appears to be closely related to D. novolympica. It is readily distinguished from that species by the primarily dendritic trichomes (and absence of simple trichomes) on the stems, pedicels, and fruits. Draba trichocarpa is known from the Stanley Basin of central Idaho (Custer County). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
R. C. Rollins (1993) treated Draba zionensis as a variety of D. asprella, but its true relationships appear to lie with two other southern Utah endemics, D. sobolifera and D. subalpina. Draba zionensis is easily distinguished from D. subalpina by having orange-yellow (versus white) petals, and from D. asprella and D. sobolifera by its glabrous (versus pubescent) pedicels and stems distally. Nearly all populations of the species are found in and around Zion National Park in southwestern Utah (Iron, Kane, and Washington counties). A specimen supposedly from the Deep Creek Mountains (Juab County) may be mislabeled. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 344. | FNA vol. 7, p. 346. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | D. asprella var. zionensis | |
Name authority | Rollins: Contr. Gray Herb. 214: 4. (1984) | C. L. Hitchcock: Revis. Drabas W. N. Amer., 49, plate 2, fig. 16. (1941) |
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