(Prunus spinosa), spiny shrub, of the rose family (Rosaceae), native to Europe but cultivated in other regions. The name is also applied to Crataegus calpodendron (or C. tomentosa), commonly called pear haw, another shrub or small tree of the rose family. P. spinosa usually grows less than 3.6 metres (12 feet) tall and has numerous, small leaves. Its dense growth makes it suitable for hedges. The white flowers, about 2 centimetres (0.8 inch) in diameter, appear before the leaves. The bluish-black, tart-flavoured fruit is about 2 cm in diameter and is used to flavour sloe gin.