Arabis harrisonii S. L. Welsh in S. L. Welsh et al., Utah Fl. ed. 3, 256. 2003; Boechera microphylla (Nuttall) Dorn var. harrisonii (S. L. Welsh) N. H. Holmgren

Perennials; long-lived; (some-what cespitose); apomictic; caudex often woody. Stems usually 3-7 per caudex branch, arising from margin of rosette near ground surface, 0.5-2.5 dm, usually sparsely pubescent proximally, rarely glabrous, trichomes short-stalked, 2- or 3-rayed, 0.06-0.2 mm, glabrous distally. Basal leaves: blade narrowly oblanceolate, 2-4 mm wide, margins entire or somewhat dentate, ciliate near petiole base, trichomes (simple), to 0.5 mm, surfaces sparsely pubescent, trichomes short-stalked, 2-5-rayed, 0.1-0.25 mm. Cauline leaves: 3-7, not concealing stem; blade auricles 0.5-1.5 mm, surfaces of distalmost leaves glabrous. Racemes 5-12-flowered, usually unbranched. Fruiting pedicels divaricate-ascending, straight, 8-12 mm, glabrous. Flowers ascending at anthesis; sepals pubescent; petals lavender, 5-7.5 × 0.8-1.5 mm, glabrous; pollen spheroid. Fruits usually divaricate-ascending, rarely nearly horizontal, not appressed to rachis, not secund, curved to straight, edges parallel, 3-4.7 cm × 1-1.5 mm; valves glabrous; ovules 64-86 per ovary; style 0.2-0.5 mm. Seeds uniseriate, 1.1-1.3 × 0.8-1.1 mm; wing continuous, 0.08-0.1 mm wide.

Flowering May-Jun. Limestone and quartzite cliffs; 1500-1600 m; Utah.

Morphological evidence suggests that Boechera harrisonii is an apomictic species that arose through hybridization between B. microphylla and B. perennans (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). Boechera harrisonii is known only from Utah and Wasatch counties in north-central Utah.