Crossing Experiments

Some closely controlled experiments were carried out at Christchurch and at Cass, where plants of the four different species were used to assess relative amounts of fruit set by female and hermaphrodite plants upon artifical crossing. Selfing of hermophrodites and cross pollination of hermaphrodites and females were used in these intraspecific crosses. No adequate figures for statistical treatment were obtained and no seed could be germinated to test viability. All flower heads used were bagged prior to opening of flowers, and care was taken to avoid accidental crosses. In all cases females set fruit in a high percentage of flowers, but very few attempts at crossing and selfing of hermaphrodites were successful. Enough evidence was gathered to show that P. “snow tussock”, P. “short tussock” and P. prostrata (the two latter more rarely) can all set fruit through self pollination of hermaphrodite flowers, but it is obvious that this is less efficacious than cross pollination of females. Cross pollination of emasculated hermaphrodites also results in a low percentage of fruit set in P. “snow tussock”.. Upon selfing, only a few fruit per head were set at Christchurch on P. “snow tussock” hermaphrodites but P. traversii hermaphrodites at Cass showed higher self fertility (8–10%). Artificial crosses with hermaphrodites thus resulted in fruit set comparable with that in natural conditions. Dr. E. Godley (pers comm.) has verified self fertility of hermaphrodites for P. traversii.