PLACENTAL POLLINATION IN LILIUM-LONGIFLORUM THUNB

In Lilium longiflorum placental pollination was carried out to study t he interaction between the pollen tube and the placenta with ovules. T he pollen tube growth between the ovules seems directed and the pollen tubes do find the inner integument. A reaction to the inner integumen t or the micropyle is observed, but rarely results in ovule penetratio n. Attempts to activate the ovules did not increase the percentage pen etration. Only grafting a style with pollen tubes to the placenta gave a 5-fold increase. The low penetration percentage after placental pol lination seems to have its basis in an inability of the pollen tubes t o react to signals from the micropyle. The poor results from placental pollination and grafted style pollination are compared mutually and w ith those from the routinely used cut-style pollination technique in o rder to give more insight in the processes that attract the pollen tub es to the micropyles.