Draba burkei

(C. L. Hitchcock) Windham & Beilstein

Madroño 50: 221. 2004.

Basionym: Draba maguirei var. burkei C. L. Hitchcock Revis. Drabas W. N. Amer., 72, plate 5, fig. 37c. 1941
Treatment appears in FNA Volume 7. Treatment on page 298. Mentioned on page 280, 308.

Perennials; (cespitose, forming loose mats); caudex branched (with persistent leaves, branches sometimes terminating in sterile rosettes); scapose. Stems unbranched, 0.3–0.6 (–0.9) dm, glabrous. Basal leaves subrosulate; subsessile; blade oblanceolate to obovate, 0.3–0.8 (–1.3) cm × 1–2.5 mm, margins entire, (ciliate, trichomes simple, subsetiform, 0.25–0.8 mm), surfaces glabrous. Cauline leaves 0. Racemes 4–10-flowered, ebracteate, elongated in fruit; rachis not flexuous, glabrous. Fruiting pedicels divaricate-ascending to ascending, straight, 4–9 (–15) mm, glabrous. Flowers: sepals broadly ovate, 2–3.5 mm, glabrous or sparsely pubescent, (trichomes simple, 0.07–0.35 mm); petals yellow, oblanceolate, 4–6 × 1.5–2 mm; anthers ovate, 0.4–0.5 mm. Fruits ovate, plane, flattened, 3–5.5 × 2–3.2 mm; valves glabrous or puberulent, trichomes simple, 0.02–0.08 mm; ovules 4–10 per ovary; style 0.5–1.7 mm. Seeds ovoid, 1–1.4 × 0.7–1 mm. 2n = 20.


Phenology: Flowering May–Jul.
Habitat: Rocky ridges, steep talus slopes, rock outcrops and crevices
Elevation: 1600-3000 m

Discussion

Of conservation concern.

Draba burkei was treated by C. L. Hitchcock (1941) and R. C. Rollins (1993) as a variety of D. maguirei. Chromosome numbers (2n = 20 versus 2n = 32), plant morphology, and molecular data support the recognition of these taxa as independent species (M. D. Windham 2004). Draba burkei is easily distinguished from D. maguirei by having exclusively simple trichomes confined to leaf blade margins (versus mostly branched trichomes on margins and surfaces) and smaller seeds (1–1.4 × 0.7–1 versus 1.6–2 × 1–1.3 mm). It is known from Box Elder, Cache, Morgan, and Weber counties, where it approaches but does not overlap the range of D. maguirei. Draba burkei (as D. maguirei var. burkei) is in the Center for Plant Conservation’s National Collection of Endangered Plants and is listed in NatureServe as a plant of conservation concern.

Selected References

None.

Lower Taxa

None.

"elongated" is not a number."thick" is not a number."dm" is not declared as a valid unit of measurement for this property."dm" is not declared as a valid unit of measurement for this property.

... more about "Draba burkei"
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
Ihsan A. Al-Shehbaz +, Michael D. Windham +  and Reidar Elven +
(C. L. Hitchcock) Windham & Beilstein +
Draba maguirei var. burkei +
appendaged +  and unappendaged +
0.8 cm8 mm <br />0.008 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
not +  and auriculate +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
lobed +, toothed +  and entire +
oblanceolate;obovate +
much smaller +  and reduced +
0.1 cm1 mm <br />0.001 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
urceolate +, campanulate +  and tubular +
scapose +  and branched +
sessile +  and petiolate +
well-developed +
distinct +
well-differentiated +
emarginate +  and entire +
1600-3000 m +
straight +  and curved +
not winged +  and unappendaged +
connate +  and distinct +
not basally +  and dilated +
actinomorphic +
orange;purple;orange;purple;pink;white;yellow +
spreading +, ascending +  and erect +
linear +, oblanceolate +, spatulate +, obovate +, subsaccate +, not saccate +, oblong +  and ovate +
latiseptate +, twisted +  and sessile +
indehiscent +  and dehiscent +
0.3 cm3 mm <br />0.003 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
flattened +, plane +  and ovate +
0.2 cm2 mm <br />0.002 m <br /> (0.32 cm3.2 mm <br />0.0032 m <br />) +
Rocky ridges, steep talus slopes, rock outcrops and crevices +
sessile +  and petiolate +
alternate +, not +  and rosulate +
cauline +  and basal +
connate +  and distinct +
decurrent +
pinnatifid +
tenuinucellate +, crassinucellate +  and bitegmic +
campylotropous +  and anatropous +
rudimentary +
oblanceolate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Flowering May–Jul. +
trinucleate +  and 3(-11)-colpate +
ebracteate;4-10-flowered +
ascending +  and erect +
slender +
0.9 cm9 mm <br />0.009 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
straight +  and not flexuous +
divaricate-ascending +  and ascending +
mucilaginous +
not +  and mucilaginous +
white +, black +, brown +  and yellow +
0.1 cm1 mm <br />0.001 m <br /> (0.14 cm1.4 mm <br />0.0014 m <br />) +
0.07 cm0.7 mm <br />7.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
persistent +  and caducous +
distinct +
spreading +, ascending +  and erect +
pubescent +  and glabrous +
0.2 cm2 mm <br />0.002 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
reduced +
latiseptate +, twisted +  and sessile +
indehiscent +  and dehiscent +
terete +, plane +, subglobose +, ovoid +, suborbicular +, linear +, oblong +, elliptic +, lanceolate +  and ovate +
latiseptate +, twisted +  and sessile +
indehiscent +  and dehiscent +
terete +, plane +, subglobose +, ovoid +, suborbicular +, linear +, oblong +, elliptic +, lanceolate +  and ovate +
tetradynamous +
procumbent +  and decumbent +
prostrate +  and decumbent +
usually erect +  and ascending +
subsessile +, sessile +  and petiolate +
persistent +
distinct +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
Abdra +, Erophila +, Nesodraba +  and Tomostima +
Draba burkei +
species +
cruciform +  and forked +
0.002 cm0.02 mm <br />2.0e-5 m <br /> (0.008 cm0.08 mm <br />8.0e-5 m <br />) +
coiled +, 1-7-veined +  and veined +
puberulent +  and glabrous +
anastomosing +
scapose +  and not +
pubescent +  and glabrous +
rhizomatous +, taprooted +, scapose +  and not +
perennial +, biennial +  and annual +
subshrub +  and herb +
aquatics +  and terrestrial +
glabrous +  and pubescent +