The majority of New Zealand plants produce flowers which are small and inconspicuous. The predominant colours are white and greenish, and in many plants the flowers are unisexual, the genus Coprosma illustrating all these points. Even in plants found elsewhere with coloured flowers, as the rose coloured Calystegia sepium, the flowers in New Zealand are white. In alpine flora the flowers are much more conspicuous but are mostly white or cream in colour. Of the gentians, which are of brilliant colours in other countries, there are 24 species which are nearly all pure white or faintly streaked with colour. In Auckland Islands and other sub-Antarctic islands there are flowers with brighter colours, and the gentians range from white to crimson on different plants.
In midsummer there are bright red flowers of pohutukawa (Metrosideros excelsa) and the southern rata (M. umbellata) and the dull golden blossoms of kowhais (Sophora species). There are a few winter-flowering trees such as Neopanax arboreum with small inconspicuous unisexual flowers, and Vitex lucens with dull red flowers.
A striking feature is the number of species, about 15 per cent, which have unisexual flowers; these are mainly dioecious. Nearly all species of the two genera Clematis and Rubus are dioecious, while in Cotula and Bulbinella this habit is found only in the New Zealand species of each genus.