The rosaceae, or rose family includes herbs, shrubs and trees, characterised by alternate leaves, often divided or lobed, always with stiplues, and flowers of five (less often four) petals and sepals. Flowers of many species are subtended by an epicalyx, a whorl of bracts similar in appearance to the sepals. The petals surround a large group of stamens and pistils. At least three genera have many similar species, difficult to distinguish and sometimes very local; these are alchemilla, rubus and sorbus.