REPRODUCTIVE ISOLATION OF 2 SYMPATRIC SUBSPECIES OF JUNIPERUS-PHOENICEA (CUPRESSACEAE) IN SOUTHERN SPAIN

The phenology, reproductive cycle and cone crop of two sympatric subsp ecies of Juniperus phoenicea (Cupressaceae) were studied during three consecutive years in southern Spain. The flowering pattern of each sub species was constant during this period: in J. phoenicea subsp. turbin ata flowering was always in October-November, while J. phoenicea subsp . phoenicea flowered in February-March. There was no overlap between t he flowering periods of the two taxa. The reproductive cycle of the tw o subspecies was similar, though there were some important differences because of their flowering times. Male cone development in both subsp ecies occurred in autumn, but the male cones of J. phoenicea subsp. ph oenicea did not shed pollen until the end of February. In J. phoenicea subp. turbinata, the gap between pollination and fertilisation was se ven months while in J. phoenicea subsp. phoenicea it was only three mo nths, fertilisation taking place at the same time in the two taxa. Pos t-fertilisation events were similar in the two subspecies, leading to a cycle of two years in J. phoenicea subsp. turbinata and a shorter on e of about 20 months in J. phoenicea subsp. phoenicea. Alternating goo d and slight seed cone crops were found in both taxa during the three years studied, the good crops of one subspecies coinciding with the sl ight crops of the other one. Although the proximity of the two subspec ies and method of pollination could make hybridisation between the tax a possible, the different flowering seasons prevent hybridisation isol ating them reproductively.