The mountain broom (Cytisus oromediterraneus) is a leguminous shrub of the high siliceous mountains of central Spain, forming extensive yellow thickets known as ‘piornales’.
| Kingdom | Plantae |
| Division | Magnoliophyta |
| Class | Magnoliopsida |
| Order | Fabales |
| Family | Fabaceae |
| Genus | Cytisus |
| Species | Cytisus oromediterraneus |
It is a shrubby species with dense, compact branches, which usually takes on a cushion-like appearance as a defensive adaptation to the cold and strong summit winds. Its small yellow flowers appear between May and July.
It forms very dense stands of vegetation called ‘piornales’, generally situated above the treeline or growing alongside Scots pine.
It is a species typical of the high-altitude siliceous mountains of central and southern Europe. In Spain it dominates the vegetation of the oromediterranean zone of ranges such as Gredos and Guadarrama, and also occurs in the Pyrenees.
It has traditionally been used as fuel for ovens, for making brooms and for thatching shepherds' huts. ‘Piorno’ is in fact a common name shared by more than a dozen different species of leguminous shrubs.
