Flowers of the less specialised genera in Africa, notably Helixanthera, Taxillus and Vanwykia in the Flora area, open spontaneously or with little probing. In more advanced genera of both the Tapinanthoid and Taxilloid groups the flowers are increasingly complicated with special mechanisms that can only be manipulated by birds and various signals are developed to attract their attention. In most cases vents appear in the mature bud just below where the anthers are held in the tip of the bud, with the stamens and corolla-lobes held under tension. The region is often indicated by contrasting bands of colour on the corolla and on parts visible through the vents. Probing by the beak of the bird causes the corolla to split open explosively, either radially or unilaterally with a distinct V-split, dusting the bird s head with pollen.
Further refinements occur with a more economic and precise directing of the pollen puff.
These have occurred with a remarkable degree of convergent evolution in the two groups of genera, such that species of Agelanthus and Phragmanthera have been included within a broad concept of Tapinanthus until recently. The pollination strategy in Globimetula is quite different. Here the distinct head of the mature bud darkens and when pecked the petals coil outwards to reveal vents at the base of the staminal column, probing of which causes the stamens to coil inwards explosively, bending the style in the same direction. Pecking causes a V-shaped rent and precise deposition of pollen and inflexion of the style. The divergence of ecogeographic races and species is often marked, among other features, by shifts in signals given to visiting birds.