Biscutella laevigata Buckler Mustard
In flower Biscutella species are as tricky to identify as any other yellow crucifer but if seed are present the characteristic shape tells you immediately which genus this is. This mountain plant is quite tall compared with the very common relative Biscutella didyma but with exactly the same "shield" shaped fruits (hence scutella).
B. laevigata shares a property with a few other plants that it can be an early coloniser of waste dumps contaminated with heavy metals like cadmium, lead and even thallium of which it is very tolerant (M. Wierzbicka et. al 2003). It would be useful therefore as a plant to use initially when restoring such difficult contaminated habitats.
Bernina alps above Pontresina, Engadine, Switzerland 5th July 2010
Added on 28th July 2010