Mating system and cross-compatibility of races of Epacris impressa

The mating system and cross-compatibility of races of Epacris impressa Labill. were examined by a series of selfings, outcrosses between plants of the same race from the same and different populations, and outcrosses between plants of different races. The percentage of pollinations which gave capsules and the number of seeds present per capsule for these four types of crosses, and whether the seeds germinated, were scored. The results indicate that E. impressa is an outcrossing species with a self-incompatibility mechanism to keep selfing at a low level, the races cross freely and the hybrid seed is viable. The means over all races for the above four types of crosses were 8.7 (selfing), 62.3, 62.5 and 65.5 for the percentage of pollinations that were successful and 8.4 (selfing), 43.5, 41.2 and 39.0 for the number of seeds per capsule. The results of a limited number of crosses between Epacris impressa and other epacrid species are also given.