POLLEN TUBE GROWTH AND INCOMPATIBILITY FOLLOWING INTRA‐ AND INTER‐SPECIFIC POLLINATIONS IN LILIUM LONGIFLORUM

The growth of pollen tubes of a sampling of Lilium species in styles of L. longiflorum incubated at 24 C for 48 hr after pollination indicated two types of interspecific incompatibility. Pollen tubes of two self-compatible species of section Leucolirion, the section including L. longiflorum, stopped growth abruptly upon reaching the stylar canal, were of abnormal morphology, and were incapable of continued growth with longer incubation. Pollen tubes of self-compatible or self-incompatible species of sections Sinomartagon, Pseudolirium, Liriotypus, and Daurolirion approached but did not exceed the length of intraspecific incompatible pollen tubes in styles of L. longiflorum. Pollen tube morphology was normal and tubes were capable of continued growth with additional incubation. Unilateral interspecific incompatibility occurred in reciprocal crosses between self-incompatible L. longiflorum and self-compatible L. regale and L. formosanum, but exceptions occurred in Aurelian hybrids. Incubation of interspecifically pollinated L. longiflorum styles at 39 C, which removes the self-incompatibility reaction, had no effect on interspecific incompatibility.