The flowers have insignificant petals and are wind-pollinated, with long anthers and stigmas.

The fruit is a non-poisonous juicy berry, most often bright orange (but can be dark red or even light blue), containing two small seeds.

The orange fruit of the larger species were eaten by Māori children, and are also popular with birds.

A notable feature (also found in other genera of Rubiaceae) is that the leaves contain hollows in the axils of the veins; in these, and on the leaf stipules, nitrogen-fixing bacteria grow.

In addition the hollows, or domatia, encourage certain kinds of mites to take up residence, which feed on and reduce parasitic fungi which attack the leaf.