COMPARATIVE REPRODUCTIVE BIOLOGY OF ALPINE BIENNIAL AND PERENNIAL GENTIANS (GENTIANA: GENTIANACEAE) IN CALIFORNIA

Reproductive characteristics of three sympatric species of Gentiana exhibiting perennial and non-perennial life histories were studied in alpine meadows of the White Mountains of California during three consecutive years. High fruit and seed set and the production of a relatively large number of seeds characterized the alpine biennials, Gentiana tenella and G. prostrata. In contrast, fruit and seed set were considerably reduced and yearly seed production was relatively low in the alpine perennial, G. newberryi. Successful seed production in the biennial species was a result of low rates of flower predation, self-pollination, and the allocation of a comparatively high proportion of biomass to reproductive structures. Seed production in the perennial species was limited by high rates of flower predation, insufficient amounts of pollen reaching stigmas, an unusually late flowering period, and by the relatively small proportion of biomass allocated to reproduction.