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Montana Field Guide

Montana Field Guides

Small-leaf Rockcress - Boechera microphylla var. macounii

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Native Species

Global Rank: G5
State Rank: SNR

Agency Status


External Links

General Description
This description follows Al-Shehbaz and Windham (2006, Fl. North America, Vol. 7), who treat it as a species, but who recognize the species only in WA and OR:

FNA | Family List | FNA Vol. 7 | Brassicaceae | Boechera

10. Boechera cascadensis Windham & Al-Shehbaz, Harvard Pap. Bot. 11: 260. 2007.

Arabis microphylla Nuttall var. thompsonii Rollins, Rhodora 43: 429. 1941, not Boechera thompsonii (S. L. Welsh) N. H. Holmgren 2005

Cespitose, long-lived perennials; caudex somewhat woody. Stems usually 1 per caudex branch, arising from center of rosette near ground surface, 0.5-2.2 dm, sparsely pubescent proximally, hairs simple and short-stalked, 2- or 3-rayed, 0.1-0.2 mm, glabrous distally. Basal leaves: blade linear-oblanceolate, 0.7-2 mm wide, margins entire, ciliate proximally, hairs to 0.4 mm, surfaces densely pubescent, hairs short-stalked, (2- or) 3-6-rayed, 0.05-0.2(-0.3) mm. Cauline leaves: 4-6, not concealing stem; blade auricles 0.5-1 mm, surfaces of distal-most leaves glabrous. Racemes 3-11-flowered, unbranched. Fruiting pedicels ascending to divaricate-ascending, straight, 3-8 mm, glabrous. Flowers ascending at anthesis; sepals glabrous or sparsely pubescent; petals lavender, 5-6 × 1-1.7 mm, glabrous. Fruits ascending to divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, 3.5-6.2 cm × 1.2-1.5 mm; valves glabrous; style 0.8-1.5 mm. Seeds uniseriate, 1.1-1.3 × 0.9-1 mm; wing continuous, 0.05-0.1 mm wide.

Flowering in June.

Range Comments
WA and OR (Al-Shehbaz and Windham 2010; Kartesz 2009).

Observations in Montana Natural Heritage Program Database
Number of Observations: 1

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

"Basaltic cliffs and rocky slopes in subalpine areas; of conservation concern; ca. 1900 m" (Al-Shehbaz and Windham 2010).

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Citation for data on this website:
Small-leaf Rockcress — Boechera microphylla var. macounii.  Montana Field Guide.  .  Retrieved on , from