Boechera platysperma

(A. Gray) Al-Shehbaz

Novon 13: 388. 2003.

Basionym: Arabis platysperma A. Gray Proc. Amer. Acad. Arts 6: 519. 1865
Synonyms: Arabis inamoena Greene Arabis oligantha Greene
Treatment appears in FNA Volume 7. Treatment on page 397. Mentioned on page 353, 375, 385, 398, 411.

Perennials; long-lived; sexual; caudex woody. Stems usually 1 per caudex branch, arising from center of rosette, elevated on woody base above or near ground surface, 0.6–2.8 (–3.5) dm, densely pubescent proximally, trichomes short-stalked, 2–5-rayed, 0.1–0.3 mm, glabrous or sparsely pubescent distally. Basal leaves: blade narrowly oblanceolate, 3–7 (–10) mm wide, margins entire, ciliate near petiole base, trichomes (simple or spurred), to 1 mm, surfaces densely pubescent, trichomes short-stalked, 2–4 (or 5) -rayed 0.1–0.3 mm. Cauline leaves: 3–7 (–12), not concealing stem; blade auricles absent, surfaces of distalmost leaves glabrous or sparsely pubescent. Racemes 2–7-flowered, unbranched. Fruiting pedicels ascending, straight, 3–13 mm, glabrous or sparsely pubescent, trichomes appressed, branched. Flowers ascending at anthesis; sepals pubescent; petals creamy white to purplish, 4–6 × 1–2 mm, sparsely pubescent (often some trichomes abaxially); pollen ellipsoid. Fruits ascending, not appressed to rachis, not secund, straight to slightly curved, edges undulate (not parallel), (2.5–) 4–8.5 cm × 3–5.5 mm; valves glabrous; ovules 16–44 per ovary; style 0.05–1 mm. Seeds uniseriate, 3–6 (–8) × 2–3.5 mm; wing continuous, 0.8–2.5 mm wide. 2n = 14.


Phenology: Flowering Jun–Aug.
Habitat: Rock outcrops and gravelly soil in dry pine forests and lodgepole-chaparral woodlands
Elevation: 1600-3000 m

Discussion

Previous authors have adopted broader circumscriptions of Boechera platysperma, including plants herein called B. covillei, B. elkoensis, and B. howellii. In our opinion, the differences between these taxa are sufficient to justify their treatment as distinct species (see M. D. Windham and I. A. Al-Shehbaz 2006, 2007, 2007b for detailed comparison). Reports of B. platysperma from Nevada (e.g., R. C. Rollins 1993; N. H. Holmgren 2005b) are based on plants of B. howellii or apomictic hybrids with other species.

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.

... more about "Boechera platysperma"
oblong +  and ovate +
Ihsan A. Al-Shehbaz +  and Michael D. Windham +
(A. Gray) Al-Shehbaz +
not +  and rosulate +
Arabis platysperma +
appendaged +  and unappendaged +
lyrate-pinnatifid +, dentate +  and entire +
dissected +, repand +, sinuate +, crenate +  and dentate +
oblanceolate +
much smaller +  and reduced +
3mm;7mm +
urceolate +, campanulate +  and tubular +
branched +  and simple +
petiolate +  and sessile +
well-developed +
indistinct +
not +  and differentiated +
emarginate +  and entire +
Calif. +  and Oreg. +
2.5 cm25 mm <br />0.025 m <br /> (4 cm40 mm <br />0.04 m <br />) +
4 cm40 mm <br />0.04 m <br /> (8.5 cm85 mm <br />0.085 m <br />) +
undulate +
0.3 cm3 mm <br />0.003 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
1600-3000 m +
straight +  and curved +
not winged +  and unappendaged +
connate +  and distinct +
actinomorphic +
straight +  and slightly curved +
torulose +, falcate +, lanceolate +, oblong +  and linear +
Rock outcrops and gravelly soil in dry pine forests and lodgepole-chaparral woodlands +
annular +  and semiannular +
sessile +  and petiolate +
alternate +, not +  and rosulate +
cauline +  and basal +
connate +  and distinct +
decurrent +
pinnatifid +
prominent +  and obscure +
tenuinucellate +, crassinucellate +  and bitegmic +
campylotropous +  and anatropous +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
rudimentary +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Flowering Jun–Aug. +
trinucleate +  and 3(-11)-colpate +
ellipsoid +
unbranched;2-7-flowered +
elongated +
reflexed +, ascending +  and erect +
slender +
mucilaginous +
margined +, not winged +  and winged +
biseriate +, sub-biseriate +  and uniseriate +
0.6 cm6 mm <br />0.006 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
not +  and mucilaginous +
White (?) +, Black (?) +, Brown (?) +  and Yellow (?) +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
orbicular +, oblong +  and flattened +
0.2 cm2 mm <br />0.002 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
persistent +  and caducous +
distinct +
spreading +, ascending +  and erect +
oblong +  and ovate +
reduced +
latiseptate +, schizocarpic +, samaroid +  and lomentaceous +
indehiscent +  and dehiscent +
angustiseptate +, flat +, angled +, terete +, torulose +, not +, segmented +  and nutletlike +
tetradynamous +
branched +  and unbranched +
procumbent +  and decumbent +
subsessile +, sessile +  and petiolate +
persistent +
distinct +
0.005 cm0.05 mm <br />5.0e-5 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
pubescent +  and glabrous +
Arabis inamoena +  and Arabis oligantha +
Boechera platysperma +
Boechera +
species +
branched +  and short-stalked +
pubescent +  and glabrous +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
coiled +, 1-7-veined +  and veined +
anastomosing +
perennial +  and long-lived +
pubescent +  and glabrous +
0.3 cm3 mm <br />0.003 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
rhizomatous +, taprooted +, scapose +  and not +
perennial +, biennial +  and annual +
subshrub +  and herb +
aquatics +  and terrestrial +
glabrous +  and pubescent +
0.8mm;2.5mm +