Direct pollination of Zea mays ovules in vitro with Z. mays, Z. mexicana and Sorghum bicolor pollen.

Sorghum (Sorghum bicolor) pollen tubes penetrated and grew in corn (Zea mays) styles. The limited length of the sorghum pollen tubes (3-5 mm) and the absence of stigmatic hairs on the basal (5-10 mm) section of the corn styles prevented effective pollination in vivo and in vitro. Normal fertilisation occurred after in vitro pollination of exposed corn ovules with either corn or teosinte (Zea mexicana) pollen. Six per cent of corn ovules pollinated directly with sorghum pollen responded by rapid, massive growth of nucellar tissue.