The scorpion senna (Coronilla emerus subsp. emerus [= Hippocrepis emerus subsp. emerus]) is a deciduous shrub belonging to the large legume family Fabaceae.
The leaves are imparipinnate with 2-4 pairs of lateral leaflets and a single terminal leaflet. The flowers display a yellow corolla of bilateral symmetry that is typical from the Fabaceae. However, their petals have a particular narrow claw that is much longer than the calyx. The legume is 4-11 cm in length, narrow, divided into segments reminding a scorpion tail, and it hangs down.
The scorpion senna grows mostly in oak forests, but it is also a common plant in the Montserrat massif where holm oak forests are commonplace.
The scorpion senna is similar to Cytisophyllum sessilifolium that inhabits same places, but both shrubs differ because Cytisophyllum sessilifolium has three leaflets leaves and their legumes are unsegmented, flat and stand up.
[photos Jordi Badia]