Description: Perennial, occasionally annual, herbs, hispid with spreading hairs.
Leaves opposite to alternate, margins entire.
Inflorescence terminal, of 1 or more scorpioid cymes. Corolla actinomorphic, rotate, blue or white; tube very short. Stamens exserted, anthers narrow-ovoid with the long terminal appendages twisted around each other, ± sessile. Ovary slightly lobed, 4-locular with 1 ovule per loculus; style terminal, simple; stigma small, capitate.
Fruit splitting into 4 obovoid mericarps leaving the persistent gynobase.
Distribution and occurrence: World: c. 35 species, trops & subtrops, Africa & Asia. Australia: 1 species (native).
Text by Peter G. Wilson