Synstemon deserticola Y. Z. Zhao; S. petrovii var. pilosus Botschantzev; S. petrovii var. xinglongicus Z. X. An; Synstemonanthus petrovii (Botschantzev) Botschantzev; S. petrovii var. pilosus (Botschantzev) Botschantzev.

Herbs annual, 15-30 cm tall. Stems often branched basally and above, sparsely pilose or glabrescent. Basal leaves shortly petiolate, not rosulate, often withered by flowering, pinnatipartite, 1-2 cm × 3-5 mm, apex acute. Cauline leaves linear, sessile, 0.5-4 cm × 0.5-1.7 mm, somewhat fleshy, margin entire, apex acute, sparsely pilose. Fruiting pedicels divaricate or ascending, slender, glabrous, 4-10 mm. Sepals oblong, 2-2.5 × 0.9-1.2 mm, glabrous or densely pilose. Petals lilac, obovate, 4-5.5 × 1.7-2.8 mm, apex rounded; claw 1-2.5 mm, sparsely to densely pilose. Filaments of median stamens 2-3.5 mm, united at base, sparsely to densely pilose on basal half; lateral stamens 1-2 mm, pilose basally; anthers oblong, 0.6-0.8 mm. Ovules 20-24 per ovary. Fruit linear, compressed, (0.5-)1.3-3 cm × 0.8-1.5 mm, straight; valves sparsely pubescent basally when young, soon glabrescent, with a distinct midvein; gynophore ca. 0.5 mm; style 0.5-1 mm. Seeds oblong, 1.2-1.7 × 0.7-0.9 mm. Fl. and fr. Jun.

* Slopes, deserts, rocky and sandy flats; 1500-2400 m. Gansu, Nei Mongol.