Article from Bean's Trees and Shrubs Hardy in the British Isles
Recommended citation
'Vella' from the website Trees and Shrubs Online (treesandshrubsonline.
A genus of three shrubby species in Spain and N. Africa. Flowers yellow, with clawed petals, borne in racemes. Filaments of inner stamens paired and connate. The elongated pod-like fruit is of distinctive shape: it is constricted around the middle and only the lower portion is fertile, the upper sterile part forming a beak.