D.Don
Description
Erysimum robustum is a Himalayan wallflower distributed through Nepal, northern India and SW China (Xizang and Yunnan), as reflected in the GBIF country records (NP, IN, CN) and some 89 occurrences. The plants illustrated here were photographed in western Nepal at Talphi (c. 2,830 m) and in the Chauta valley (c. 2,800 m) in July. It is a montane to subalpine species favouring open, well-drained sites: stony pastures, dry slopes, roadside banks and the margins of cultivation, generally between 2,500 and 3,800 m, where it forms conspicuous yellow-flowered stands during the summer monsoon. The GBIF backbone treats the name as a synonym, but it is here regarded as the accepted name Erysimum robustum following regional floristic usage.
It is a biennial or short-lived perennial herb with an erect, robust, often branched stem clothed, like the rest of the plant, in appressed two- to several-rayed malpighiaceous hairs that give a greyish cast. The leaves are linear to oblanceolate, entire to remotely denticulate, the lower ones petiolate and the upper sessile. The inflorescence is an elongating ebracteate raceme of bright yellow flowers with four clawed petals in the cruciferous pattern and tetradynamous stamens. The fruit is a long, narrow, four-angled siliqua, somewhat torulose and ascending on a stout pedicel, containing a single row of oblong seeds in each locule.
The genus Erysimum is taxonomically difficult owing to extensive variation in indumentum and habit, and several Himalayan entities have been variously lumped or split; trichome branching patterns and siliqua characters remain the most reliable diagnostic features. As a widespread, weedy-tolerant species of disturbed montane ground, E. robustum is not of conservation concern and can act as an early colonist of bare slopes.
Author: D.Don · Sources: POWO (Kew), Flora of China Vol. 8, Flora of Nepal, GBIF, Polatschek: Revision der Gattung Erysimum