Arabis tibetica Hook. fil. & Thomson

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.

Although both FRPS and Fl. Xizang. (2: 370. 1985) recognized "Arabis attenuata" as a good species, that name was never validly published, but was merely listed as a questionable synonym in the protologue of A. tibetica. The same two floras recognized A. tibetica as Arabidopsis tibetica, a position that might indeed prove correct with further studies.

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.

Herbs biennial, (4-)10-35(-50) cm tall, sparsely to densely covered basally with a mixture of simple and stalked, forked, stellate, or subdendritic trichomes, sometimes one type predominant, rarely mostly with simple trichomes, often glabrous or glabrescent on distal parts. Stems erect or ascending, few to several from base. Basal leaves rosulate; petiole 0.5-2(-3.5) cm; leaf blade spatulate, obovate, or oblanceolate, 0.5-2.5(-4) cm × 3-10 mm, base cuneate or attenuate, margin dentate or lyrate-dentate, apex obtuse or rounded. Middle cauline leaves shortly petiolate, linear-oblanceolate or oblong-obovate, 0.5-1.5(-2) cm × (1-)2-4 mm, base attenuate, margin entire or dentate. Racemes ebracteate. Fruiting pedicels divaricate or ascending, (2-)4-9(-12) mm, slender, straight. Sepals oblong, 1.5-3 × 0.8-1.3 mm, not saccate. Petals white or rarely pinkish, narrowly oblanceolate, 3-5 × 1-1.5 mm. Filaments 2-3.5 mm; anthers oblong, 0.4-0.7 mm. Ovules 30-60 per ovary. Fruit (2.5-)3.5-6(-7) cm × 1-1.5 mm, attenuate to apex; valves glabrous, torulose, with an obscure midvein; style slender (0.5-)1-3 mm. Seeds brown, oblong, 0.9-1.2 × 0.5-0.7 mm, flattened, uniseriate, wingless or rarely apically with a narrow wing. Fl. May-Jun, fr. Jun-Jul.

Distribution: Himalayas, Pakistan, Afghanistan and C. Asia.

Xizang [Afghanistan, Kashmir, Kyrgyzstan, Pakistan, Tajikistan].

Fl. Per.: May-July.

Grassy slopes; 3000-4700 m.

Arabidopsis tibetica (J. D. Hooker & Thomson) Y. C. Lan & Z. X. An; Arabis clarkei O. E. Schulz; A. multicaulis Pampanini; A. tenuirostris O. E. Schulz; A. thomsonii J. D. Hooker.