F. Gugerli, HYBRIDIZATION OF SAXIFRAGA-OPPOSITIFOLIA AND SAXIFRAGA-BIFLORA (SAXIFRAGACEAE) IN A MIXED ALPINE POPULATION, Plant systematics and evolution, 207(3-4), 1997, pp. 255-272
Saxifraga oppositifolia, S. biflora, and their hybrid S. x kochii were
studied in a mixed population in the Swiss Alps. Qualitative morpholo
gical characters did not allow to clearly separate the hybrid S. x koc
hii from its parental species. All quantitative characters were interm
ediate in S. x kochii, but the ranges of these characters overlapped w
ith those of S. oppositifolia and S. biflora. A hybrid index and canon
ical discriminant analysis allowed a clear separation of the three gro
ups and strongly confirmed a priori grouping. Phenological observation
s showed that the three groups were not temporally separated within th
e investigated mixed population. Reciprocal hand pollinations between
S. oppositifolia and S. biflora yielded higher seed set with S. opposi
tifolia than with S. biflora as maternal plant. Germination rate of se
eds from these crossing experiments varied in the same way as seed yie
lds, whereas germination rate was intermediate for seeds from naturall
y pollinated S. x kochii. Considering its ecological and reproductive
properties, S. x kochii has good prerequisites for evolving into a dis
tinct species.