pollination, the transfer of pollen from the anther to the receptive stigmatic surface. If pollination occurs with the pollen and pistil of the same flower, the process is called self-pollination and the progeny is known as a selfling or selfed vine; if it occurs between two different flowers (whether from the same vine or from different vines), the process is called cross-pollination. In cultivated grapevines, flowers are hermaphroditic and most are self-pollinated before the calyptra has fallen (cleistogamy), but cross-pollination may also occur. Fertilization occurs two or three days after pollination depending on the ambient temperature (see flowering). Wild grapes (Vitis silvestris) and some primitive cultivars are dioecious (male-only or female-only plants), therefore cross-pollination is essential.