Boechera oxylobula

(Greene) W. A. Weber

Phytologia 51: 370. 1982.

Basionym: Arabis oxylobula Greene Pittonia 4: 195. 1900
Synonyms: Arabis aprica Osterhout ex A. Nelson Arabis demissa Greene Arabis rugocarpa Osterhout Boechera demissa (Greene) W. A. Weber
Treatment appears in FNA Volume 7. Treatment on page 391. Mentioned on page 351, 352, 387, 392.

Perennials; short to long-lived; (cespitose); sexual; caudex usually not woody. Stems usually 3–7 per caudex branch, arising from margin of rosette near ground surface, or arising laterally proximal to sterile shoots, 0.4–2.5 dm, glabrous or pubescent proximally, trichomes simple and short-stalked, 2-rayed, 0.1–0.4 mm, glabrous distally. Basal leaves: blade linear to linear-oblanceolate, 1–2.5 mm wide, margins usually entire, rarely denticulate, often ciliate, trichomes (simple), 0.3–0.7 mm, surfaces glabrous or sparsely pubescent, trichomes short-stalked, 2-rayed or 3-rayed, 0.1–0.4 mm. Cauline leaves: 3–12, not concealing stem; blade auricles absent, surfaces of distalmost leaves usually glabrous, rarely sparsely pubescent. Racemes 2–12-flowered, unbranched. Fruiting pedicels divaricate-ascending to horizontal, slightly to strongly recurved, 3–8 mm, glabrous or sparsely pubescent, trichomes (isolated), simple. Flowers ascending-divaricate at anthesis; sepals glabrous or pubescent; petals white to pale lavender, 4–5 × 1.5–2 mm, glabrous; pollen ellipsoid. Fruits pendent, not appressed to rachis, not or, rarely, weakly secund, straight, edges parallel, 1.5–3.5 cm × 1.2–2 mm; valves glabrous; ovules 28–44 per ovary; style 0.1–0.4 mm. Seeds uniseriate, 0.9–1.2 × 0.6–1 mm; wing often continuous, 0.07–0.1 mm wide.


Phenology: Flowering May–Jul.
Habitat: Cliffs, rocky slopes, gravelly soil in sagebrush and open conifer forests
Elevation: 2100-3600 m

Discussion

Most of the collections assigned here have been called Arabis (Boechera) demissa by other authors (e.g., R. C. Rollins 1993; N. H. Holmgren 2005b). Because the holotype of A. demissa is identical to B. oxylobula in nearly every way (see M. D. Windham and I. A. Al-Shehbaz 2006 for detailed comparison), we treat them as conspecific. Boechera oxylobula is restricted to Garfield, Gunnison, Hinsdale, Lake, Mineral, Park, and Saguache counties in central Colorado. The taxon traditionally treated as A. (Boechera) demissa var. languida is here recognized as an apomictic species of hybrid origin (see Windham and Al-Shehbaz 2007b for detailed comparison).

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 oxylobula"
oblong +  and ovate +
Ihsan A. Al-Shehbaz +  and Michael D. Windham +
(Greene) W. A. Weber +
not +  and rosulate +
Arabis oxylobula +
appendaged +  and unappendaged +
not +  and auriculate +
lyrate-pinnatifid +, dentate +  and entire +
dissected +, repand +, sinuate +, crenate +  and dentate +
linear;linear-oblanceolate +
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 +
branched +  and simple +
petiolate +  and sessile +
well-developed +
indistinct +
not +  and differentiated +
emarginate +  and entire +
1.5 cm15 mm <br />0.015 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
0.12 cm1.2 mm <br />0.0012 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
2100-3600 m +
straight +  and curved +
not winged +  and unappendaged +
connate +  and distinct +
actinomorphic +
ascending-divaricate +
straight +
torulose +, falcate +, lanceolate +, oblong +  and linear +
Cliffs, rocky slopes, gravelly soil in sagebrush and open conifer forests +
annular +  and semiannular +
sessile +  and petiolate +
alternate +, not +  and rosulate +
cauline +  and basal +
connate +  and distinct +
decurrent +
denticulate +
prominent +  and obscure +
tenuinucellate +, crassinucellate +  and bitegmic +
campylotropous +  and anatropous +
white +  and pale lavender +
rudimentary +
oblanceolate +  and spatulate +
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 +
ellipsoid +
unbranched;2-12-flowered +
reflexed +, ascending +  and erect +
slender +
mucilaginous +
margined +, not winged +  and winged +
biseriate +, sub-biseriate +  and uniseriate +
not +  and mucilaginous +
white +, black +, brown +  and yellow +
0.09 cm0.9 mm <br />9.0e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
orbicular +, oblong +  and flattened +
0.06 cm0.6 mm <br />6.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
persistent +  and caducous +
distinct +
spreading +, ascending +  and erect +
pubescent +  and glabrous +
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 +
pubescent +  and glabrous +
3 +  and 7 +
subsessile +, sessile +  and petiolate +
persistent +
distinct +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
pubescent +  and glabrous +
Arabis aprica +, Arabis demissa +, Arabis rugocarpa +  and Boechera demissa +
Boechera oxylobula +
Boechera +
species +
simple +  and short-stalked +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
coiled +, 1-7-veined +  and veined +
anastomosing +
perennial +  and long-lived +
divaricate-ascending +  and horizontal +
pubescent +  and glabrous +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
rhizomatous +, taprooted +, scapose +  and not +
perennial +, biennial +  and annual +
subshrub +  and herb +
aquatics +  and terrestrial +
glabrous +  and pubescent +
0.07mm;0.1mm +