Boechera davidsonii

(Greene) N. H. Holmgren in A. Cronquist et al.

in A. Cronquist et al., Intermount. Fl. 2(B): 368. 2005.

Basionym: Arabis davidsonii Greene Leafl. Bot. Observ. Crit. 2: 159. 1911
Synonyms: Arabis bruceae M. E. Jones Arabis cognata Jepson Arabis davidsonii var. parva Rollins Arabis lyallii var. davidsonii (Greene) Smiley
Treatment appears in FNA Volume 7. Treatment on page 372. Mentioned on page 351, 373, 389, 406, 410.

Perennials; long-lived; (cespitose); sexual; caudex woody (thickly covered by persistent, crowded leaf-bases). Stems usually 1 per caudex branch, arising from center of rosette near ground surface, 0.6–2.3 dm, glabrous throughout. Basal leaves: blade oblanceolate, 3.5–14 mm wide, margins usually entire, rarely slightly dentate, not ciliate, surfaces glabrous. Cauline leaves: 3–10, not concealing stem; blade auricles absent, glabrous. Racemes 4–24-flowered, usually unbranched. Fruiting pedicels ascending, straight, 3–18 mm, glabrous. Flowers ascending at anthesis; sepals glabrous; petals white to lavender, 6–10 × 2.5–4 mm, glabrous; pollen ellipsoid. Fruits ascending to divaricate-ascending, not appressed to rachis, not secund, straight to slightly curved, edges parallel, 2.5–7 cm × 1.5–2.5 mm; valves glabrous; ovules 28–50 per ovary; style 0.1–0.8 mm. Seeds uniseriate, 1.8–2.2 × 0.8–1.7 mm; wing distal or continuous, 0.1–0.5 mm wide.


Phenology: Flowering Apr–Jul.
Habitat: Ledges and crevices of rock outcrops
Elevation: 1200-3400 m

Discussion

Plants of Boechera davidsonii sometimes are confused with completely glabrous individuals of B. lyallii, and G. A. Mulligan (1996) treated it as a synonym of the latter. It is easily distinguished from B. lyallii by the thick covering of persistent leaf bases on caudex branches, ascending (versus erect and appressed) fruits, and uniseriate (versus biseriate to sub-biseriate) seeds. Boechera davidsonii is nearly unique among western North American species of the genus in showing no evidence of hybridization 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 davidsonii"
oblong +  and ovate +
Ihsan A. Al-Shehbaz +  and Michael D. Windham +
(Greene) N. H. Holmgren in A. Cronquist et al. +
not +  and rosulate +
Arabis davidsonii +
appendaged +  and unappendaged +
lyrate-pinnatifid +, dentate +  and entire +
dissected +, repand +, sinuate +, crenate +  and dentate +
oblanceolate +
much smaller +  and reduced +
3.5mm;14mm +
urceolate +, campanulate +  and tubular +
branched +  and simple +
petiolate +  and sessile +
well-developed +
indistinct +
not +  and differentiated +
emarginate +  and entire +
Calif. +, Nev. +  and Oreg. +
2.5 cm25 mm <br />0.025 m <br /> (7 cm70 mm <br />0.07 m <br />) +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
1200-3400 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 +
Ledges and crevices of rock outcrops +
annular +  and semiannular +
sessile +  and petiolate +
alternate +, not +  and rosulate +
cauline +  and basal +
connate +  and distinct +
decurrent +
dentate +  and entire +
pinnatifid +
prominent +  and obscure +
tenuinucellate +, crassinucellate +  and bitegmic +
campylotropous +  and anatropous +
0.6 cm6 mm <br />0.006 m <br /> (1 cm10 mm <br />0.01 m <br />) +
rudimentary +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
Flowering Apr–Jul. +
trinucleate +  and 3(-11)-colpate +
ellipsoid +
in A. Cronquist et al., Intermount. Fl. +
unbranched;4-24-flowered +
elongated +
slender +
0.3 cm3 mm <br />0.003 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
mucilaginous +
margined +, not winged +  and winged +
biseriate +, sub-biseriate +  and uniseriate +
not +  and mucilaginous +
White (?) +, Black (?) +, Brown (?) +  and Yellow (?) +
0.18 cm1.8 mm <br />0.0018 m <br /> (0.22 cm2.2 mm <br />0.0022 m <br />) +
orbicular +, oblong +  and flattened +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.17 cm1.7 mm <br />0.0017 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 +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
Arabis bruceae +, Arabis cognata +, Arabis davidsonii var. parva +  and Arabis lyallii var. davidsonii +
Boechera davidsonii +
Boechera +
species +
dendritic +, branched +  and simple +
coiled +, 1-7-veined +  and veined +
anastomosing +
perennial +  and long-lived +
hispid +, hirsute +, pubescent +  and glabrous +
rhizomatous +, taprooted +, scapose +  and not +
perennial +, biennial +  and annual +
subshrub +  and herb +
aquatics +  and terrestrial +
glabrous +  and pubescent +
0.1mm;0.5mm +