Life History Studies on the Genus Trillium (Liliaceae) V. Reproductive Biology and Survivorship of Three Declinate‐flowered Species

Absract Three pedicellate‐declinate‐flowered species of Trillium (Liliaceae), T. vaseyi and T. flexipes , were studied for their life history characteristics, e.g., stage class structures of natural populations and reproductive features, including energy allocation to reproductive activities. The populations structures of all three species showed similar depletion structures characterized by a conspicuous decrease of individuals in the small juvenile stages, as was also observed in pedicellate‐erect‐flowered Trillium species However, with respect to reproductive characteristics, these three declinate‐flowered species showed different features from erect‐flowered species, although they belong to the same pedicellate‐flowered group. That is, these declinate‐flowered Trillium species exhibited low seed setting rates of 30% in T. catesbaei , 45% in T. vaseyi and 34% in T. flexipes , suggesting that they possess different mating systems from erect‐flowered species which showed high seed setting rates of 50–90%.