Vegetative key to the families

Either: leaves whorled; or leaves opposite and interpetiolar stipules present (Fig. 29). Herbs and woody plants
Leaves whorled, or stipules as large as leaves giving the appearance of 6–8 whorled leaves
Herbs
Stems angular, usually quadrangular, leaves narrow
Leaves in whorls of 4 or more (Sheradia, Asperula, Galium) Rubiaceae
Flowers united by their calyces into simple or compound heads
Flowers not united with each other