Experimental induction of haploid parthenogenesis in Black Cottonwood (Populus trichocarpa T. & G. ex Hook.)

Haploids are rare among forest trees. The reasons for this are that male or female gametes rarely undergo embryogeny without prior fertilization and, if they do, the haploid sporophytes thus generated typically grow slowly and will eventually be eliminated by competition from diploids. If not physically eliminated, haploids encounter serious problems at meiosis that reduce their fitness. Thus, it is not surprising that the first haploid forest tree was reported only recently (TRALAU, 1957), and in a species with effective vegetative propagation (Populus tremula L.).