Arabis thomsonii Hook. f.
Perennial herb, (5-) 10-20 cm tall, usually much branched from the base, subspreading or erect, often densely hairy with branched (sometimes stellate) hairs, rarely sub-glabrous. Rosette leaves 10-40 mm long, 3-10 mm broad, spathulate to oblanceolate, sinuate-dentate to almost entire, shortly stalked to sessile, usually densely pubescent, apex usually obtuse or rounded; cauline leaves oblong-obovate to linear, 8-20 mm long, 2-4 mm broad, toothed, lobulate to entire. Racemes 15-20-flowered, up to 10 cm long in fruit. Flowers 5-6 mm across, white, rarely pinkish, sometimes turning pale yellowish when dried; pedicels up to 9 mm long in fruit, ascending. Sepals 3-4 mm long. Petals 5-7 mm long. Stamens 3:3.5 mm long. Siliquae linear, compressed, (25-) 35-60 mm long, 1-1.5 mm broad, acute, ± straight and erect, glabrous; valves with a distinct mid-vein; style (0.5-) 1-1.5 mm long; seeds 15-25 in each locule, c. 1 mm long, hardly or not winged.
Fl. Per.: May-July.
Type: W. Tibet, Zanskar, Thomson (K).
Distribution: Himalayas, Pakistan, Afghanistan and C. Asia.
A very variable and highly polymorphic species and after going through a large number of collection in the herbaria, it becomes difficult to maintain the identity of the above given synonyms. A. quinqueloba O.E. Schulz was distinguished by larger flowers and lobed leaves but intermediate forms are not lacking. Furthermore, A. ariana Hedge (in Rech. f., l.c. 208), from Afghanistan, seems to be a smaller form of this species with aphyllous or 1-leaved flowering stems. The following species also appear to be scarcely distinct from this species.