This broom, Cytisus scoparius, is definitely not prostrate (see 4th May). Growing tall beneath a Scot's pine in Ashdown Forest this looks like a skinny, spineless, scentless gorse bush. Closer inspection reveals a lack of spines and a five-angled stem. The flowers, although very similar, lack the calyx found in gorse.
Our word broom, for brush on a long handle, comes from the plant, which was employed for the purpose. It has replaced the Old English word which is occasionally still heard: besom.