Boechera microphylla

(Nuttall) Dorn

Vasc. Pl. Wyoming ed. 3, 376. 2001.

Basionym: Arabis microphylla Nuttall in J. Torrey and A. Gray, Fl. N. Amer. 1: 82. 1838
Synonyms: Arabis tenuicula Greene
Treatment appears in FNA Volume 7. Treatment on page 390. Mentioned on page 364, 370, 380, 383, 389.

Perennials; long-lived; (cespitose); sexual or apomictic; caudex woody. Stems 1 or several per caudex branch, arising from center or margin of rosette near ground surface, 0.8–2.8 (–3.5) dm, sparsely pubescent proximally, trichomes simple and subsessile, 2-rayed, 0.3–0.6 mm, glabrous distally. Basal leaves: blade oblanceolate to linear-oblanceolate, 1–4 (–6) mm wide, margins entire or subapically toothed, ciliate proximally, trichomes (simple), to 0.6 mm, surfaces densely pubescent, trichomes short-stalked, 4–8-rayed, 0.05–0.1 mm. Cauline leaves: 2–6, not concealing stem; blade auricles 0.5–1.5 mm, surfaces of distalmost leaves glabrous. Racemes 5–17-flowered, usually unbranched. Fruiting pedicels ascending to divaricate-ascending, straight, 4–14 mm, glabrous. Flowers ascending at anthesis; sepals glabrous or pubescent; petals lavender to purple, 3.5–5.5 × 1–1.8 mm, glabrous; pollen ellipsoid or spheroid. Fruits ascending to divaricate-ascending, not appressed to rachis, not secund, straight to slightly curved, edges parallel, 3–7 cm × 1–1.5 mm; valves glabrous; ovules 52–72 per ovary; style 0.05–0.3 mm. Seeds uniseriate, 1–1.5 × 0.7–1 mm; wing often distal, ca. 0.1 mm wide. 2n = 14, 15.


Phenology: Flowering Apr–Jun.
Habitat: Cliffs and rocky slopes in sagebrush, mountain shrub, and open conifer forests
Elevation: 400-2400 m

Distribution

V7 553-distribution-map.gif

B.C., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.

Discussion

Boechera microphylla is recognizable by its minute (0.05–0.1 mm), 4–8-rayed leaf trichomes, mat-forming habit, simple and 2-rayed trichomes on stems proximally, and ascending fruits. Both sexual and apomictic collections are known; further study is needed to determine whether they truly are conspecific. The taxa traditionally treated as Arabis (Boechera) microphylla vars. macounii and thompsonii are here recognized as B. macounii and B. cascadensis, respectively (see M. D. Windham and I. A. Al-Shehbaz 2007 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."dm" is not declared as a valid unit of measurement for this property.

... more about "Boechera microphylla"
oblong +  and ovate +
Ihsan A. Al-Shehbaz +  and Michael D. Windham +
(Nuttall) Dorn +
not +  and rosulate +
Arabis microphylla +
appendaged +  and unappendaged +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
not +  and auriculate +
lyrate-pinnatifid +, dentate +  and entire +
dissected +, repand +, sinuate +, crenate +  and dentate +
oblanceolate;linear-oblanceolate +
much smaller +  and reduced +
0.1 cm1 mm <br />0.001 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
urceolate +, campanulate +  and tubular +
branched +  and simple +
petiolate +  and sessile +
well-developed +
indistinct +
not +  and differentiated +
emarginate +  and entire +
B.C. +, Idaho +, Mont. +, Nev. +, Oreg. +, Utah +, Wash. +  and Wyo. +
3 cm30 mm <br />0.03 m <br /> (7 cm70 mm <br />0.07 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
400-2400 m +
straight +  and curved +
not winged +  and unappendaged +
connate +  and distinct +
actinomorphic +
straight +  and slightly curved +
ascending +  and divaricate-ascending +
torulose +, falcate +, lanceolate +, oblong +  and linear +
Cliffs and rocky slopes in sagebrush, mountain shrub, and open conifer forests +
annular +  and semiannular +
sessile +  and petiolate +
alternate +, not +  and rosulate +
cauline +  and basal +
connate +  and distinct +
decurrent +
dentate +  and entire +
toothed;entire +
prominent +  and obscure +
tenuinucellate +, crassinucellate +  and bitegmic +
campylotropous +  and anatropous +
lavender +  and purple +
3.5mm;5.5mm +
rudimentary +
oblanceolate +  and spatulate +
0.1 cm1 mm <br />0.001 m <br /> (0.18 cm1.8 mm <br />0.0018 m <br />) +
Flowering Apr–Jun. +
trinucleate +  and 3(-11)-colpate +
spheroid +  and ellipsoid +
Vasc. Pl. Wyoming ed. +
unbranched;5-17-flowered +
ascending +  and divaricate-ascending +
slender +
0.4 cm4 mm <br />0.004 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
mucilaginous +
margined +, not winged +  and winged +
biseriate +, sub-biseriate +  and uniseriate +
not +  and mucilaginous +
white +, black +, brown +  and yellow +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
orbicular +, oblong +  and flattened +
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 +
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 +
several +  and 1 +
subsessile +, sessile +  and petiolate +
persistent +
distinct +
0.005 cm0.05 mm <br />5.0e-5 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
glabrous +  and pubescent +
Arabis tenuicula +
Boechera microphylla +
Boechera +
species +
short-stalked +, subsessile +  and simple +
0.005 cm0.05 mm <br />5.0e-5 m <br /> (0.01 cm0.1 mm <br />1.0e-4 m <br />) +
coiled +, 1-7-veined +  and veined +
anastomosing +
perennial +  and long-lived +
hispid +, hirsute +, pubescent +  and glabrous +
apomictic +  and sexual +
rhizomatous +, taprooted +, scapose +  and not +
perennial +, biennial +  and annual +
subshrub +  and herb +
aquatics +  and terrestrial +
glabrous +  and pubescent +