Seasonal pattern of biomass allocation in flowering and nonflowering specimens of three Pinguicula species

Abstract

The seasonal patterns of biomass allocation in flowering and nonflowering specimens of Pinguicula alpina L., P. villosa L., and P. vulgaris L. were compared in a subarctic environment. Pinguicula alpina had a large perennial root system, comprising 50% of the nonreproductive biomass. The other two species had smaller, annual roots, representing 5–10% of their biomass. Nonflowering specimens usually had winter buds about twice as large as flowering specimens, P. vulgaris varied, however, with site in this respect. Flowering P. alpina allocated approximately equal proportions of biomass to reproduction (flower stalk, capsule, and seeds) and over-wintering organs (bud and roots), while P. villosa's investment in reproduction was about five times that invested in the winter bud. For P. vulgaris, no correlation was found between the size of reproductive organs and the size of the bud. The number of seeds produced per capsule varied from 30 in P. villosa to 110–140 in the other two species. Seed weight was lower in P. alpina (15 μg/seed) than in P. vulgaris (24μg) and P. villosa (28μg). Plant biomass and reproductive effort varied between sites for P. vulgaris; however, this variation was apparently not related to differences in nutrient availability between sites.