Stems simple or several from base, 2-12.3 dm, pubescent proximally, trichomes predominantly dendritic, mixed with simple and long-stalked, 2-rayed ones, glabrous or sparsely pubescent distally, trichomes dendritic. Basal leaves caducous; petiole 0.5-4 cm; blade oblanceolate, (1-)3-5 cm × 6-34 mm, margins sinuate, lobed, dentate, or, rarely, subentire, surfaces pubescent, trichomes dendritic. Cauline leaves (distal) subsessile; blade oblanceolate, 3-10 cm × 1-20 mm, surfaces glabrous or glabrate. Racemes not secund, 1.5-6.7 dm in fruit. Fruiting pedicels slightly erect to divaricate-ascending, straight, (3-)3.5-8.5(-11) mm. Flowers: sepals purple or green, broadly oblong, 2.7-4 × 1.2-2 mm; petals purplish apically, spatulate to oblanceolate, 1.5-4(-5) × 0.5-2.2 mm; filaments 0.9-2.6 mm; anthers 1-1.2 mm. Fruits erect to ascending, straight, (1.5-)2.2-5.8 cm × 0.6-1.8 mm, terete; valves glabrous or sparsely pubescent; septum transparent; ovules 90-140 per ovary; style obsolete to 0.5 mm. Seeds biseriate or uniseriate, plump, not winged, oblong, 0.7-0.8 × 0.4-0.5 mm; seed coat mucilaginous when wetted; cotyledons incumbent.
Flowering Jun-Sep. Pine-oak forests, open grasslands, rolling andesitic loam soils, among volcanic rocks, igneous cliffs; 1100-3600 m; Ariz., N.Mex., Tex.; Mexico (Chihuahua, Coahuila, Distrito Federal, Durango, state of México, Michoacán, Querétaro, San Luis Potosí, Sonora).
FNA 2010, Kearney and Peebles 1969
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Small, green-stemmed herbaceous shrub, can be simple or have many branches from the base, often leafless, stems pubescent proximally, becoming less pubescent or glabrous distally, trichomes dendritic, arising from a basal rosette. Leaves: Sparse (are early deciduous and easily separated from the plant), oblanceolate, with variable margins, can be sinuate, lobed, dentate, or entire, pubescent with dendritic trichomes. Basal leaves lobed to oblanceolate, cauline leaves linear. Flowers: White or purplish, small and occasionally bunching in leaf axils, with purple or green sepals that enclose much of the petals, petals spatulate to oblanceolate, borne on slender pedicels 3-9 mm. Fruits: Long, slender, (terete) capsule, with a transparent septum and many (to 140) ovules per ovary, seeds oblong, mucilaginous when wetted. Ecology: Found on loamy, volcanic, and igneous soils, in pine-oak forests, grasslands, and along cliffs, from 3,500-12,000 ft (1067-3658 m); flowers June-September. Notes: This plant reminds me of a tall, skinny broccoli floret with only a few flowers. If you find the mysterious green stick arising from a basal rosette with few or no remaining leaves, check this species as a possibility. Ethnobotany: A decoction of the root was taken to ease childbirth, and a heated poultice of the crushed roots was applied to ease toothache. Etymology: The origin of Pennellia is unknown, but micrantha means small-flowered. Synonyms: Streptanthus micranthus, Thelypodium longifolium var. catalinense, T. micranthum Editor: LCrumbacher, 2011