Publ. Bussey Inst. Harvard Univ. 1979: 20, plates 3, 4. 1979.
Annuals, biennials, or, rarely, perennials; not scapose; densely pubescent throughout, trichomes usually subsessile and stellate, mixed with minutely stalked, dendritic ones, rarely unbranched. Stems erect [ascending], unbranched or branched proximally, branched distally. Leaves basal and cauline; petiolate or sessile; basal not rosulate, petiolate, blade margins dentate, pinnatifid, or lobed; cauline sessile, subsessile, or shortly petiolate, blade (base not auriculate), margins entire or lobed. Racemes (corymbose), considerably elongated in fruit. Fruiting pedicels divaricate, sometimes ascending or slightly reflexed, slender. Flowers: sepals widely spreading to reflexed, oblong, (equal), lateral pair not saccate basally; petals (spreading), white or lavender, obovate (longer than sepals), claw well-differentiated from blade, (apex rounded); stamens (somewhat spreading), tetradynamous; filaments not dilated basally; anthers oblong [sagittate]; nectar glands distinct, lateral and median present; (gynophore to 0.5 mm). Fruits silicles, subsessile, breaking into two 1-seeded units at maturity, didymous, suborbicular, or broader than long, winged, strongly angustiseptate; valves keeled, enclosing seeds when falling off, not winged, narrowly winged, or margined, indurated around margin, glabrous or pubescent; replum concealed by valve margin; septum complete (ca. 0.1 mm wide); ovules 2 per ovary; style relatively short or obsolete, (terete or flattened); stigma conical, decurrently 2-lobed (appearing entire). Seeds aseriate, strongly flattened, not winged, broadly oblong to suborbicular; seed coat (smooth), not mucilaginous when wetted; cotyledons accumbent to obliquely incumbent. x = 9.
sw United States, n Mexico.
Species 4 (3 in the flora).
Dimorphocarpa membranacea (Payson) Rollins is known from northern Mexico (San Luis Potosí, Tamaulipas).
Rollins, R. C. 1958. The genetic evaluation of a taxonomic character in Dithyrea (Cruciferae). Rhodora 60: 145–152.
|1||Fruit valves (7-)8-10 mm; petals (7-)8-10(-12) mm, claws not expanded basally; distal cauline leaves sessile, blades usually ovate to narrowly oblong, rarely lanceolate, bases obtuse to truncate.||Dimorphocarpa candicans|
|1||Fruit valves 4-5.5(-6.5) mm; petals (3.5-)4-7(-8) mm, claws expanded basally; distal cauline leaves shortly petiolate or subsessile, blades linear to lanceolate, bases cuneate||> 2|
|2||Distal cauline blades: margins pinnately lobed; fruit valves nearly as long as wide, rounded apically.||Dimorphocarpa pinnatifida|
|2||Distal cauline blades: margins usually entire, rarely dentate; fruit valves often longer than wide, truncate apically.||Dimorphocarpa wislizeni|