Contr. Gray Herb. 204: 138. 1973.
Annuals or biennials; (glaucous), glabrous throughout. Stems branched distally, (3–)5–10 dm. Basal leaves rosulate; petiole 0.3–3 cm; blade oblanceolate, (1.5–)2.5–14.5(–20) cm × 10–30(–42) mm, margins dentate to subpinnatifid. Cauline leaves sessile; blade lanceolate to oblong, base auriculate, margins usually entire, rarely dentate. Racemes lax or dense. Fruiting pedicels horizontal to divaricate-ascending, often upcurved, 6–9 mm. Flowers: sepals erect, purple, 5–7.5 × 1.7–2.5 mm; petals purple to lavender or white, spatulate, 10–14 × 1.2–1.7 mm, claw 4–6 mm; median filament pairs 4–6 mm; anthers linear, 3–4 mm; gynophore (slender), 3–6(–9.5) mm. Fruits ascending to divaricate or descending, straight or slightly recurved, torulose, 4.5–9 cm × 1.1–1.4 mm; ovules 80–112 per ovary; style cylindrical, (stout), 0.3–1 mm; stigma 2-lobed. Seeds 1.2–1.5 × 0.8–1.2 mm. 2n = 22.
Phenology: Flowering Mar–Jun.
Habitat: Pinyon-juniper desert shrub communities, dry hillsides
Elevation: 800-1600 m
Of conservation concern.
Thelypodiopsis ambigua is known from Kane County in Utah and from Coconino, Mohave, and Yavapai counties in Arizona.