Contrasting Demographic Characteristics of Seeds and Vegetative Propagules in an Understory Herb Syneilesis palmata (Compositae)

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Quantitative comparisons between seeds and vegetative propagules of Syneilesis palmata (Compositae) were conducted for size and size-related demographic parameters mainly in two populations in a plantation forest (forest interior and edge). Seeds were smaller than vegetative propagules and their size range was relatively small (0.8-5.7 mg). The number of vegetative propagules per mother plant was relatively constant (about two) and their size range was relatively large (the range was 0.009-8.95 g). The length of the pre-reproductive period was size-dependent. Plants from seeds required about 7 years to become fertile, while large vegetative propagules (> 1.38 g) became fertile in the growing season following their birth. The probability of survival from birth to fertile stage was also dependent on size. More than 85% of vegetative propagules larger than 0.8 g could survive to reproduction. Smaller vegetative propagules suffered higher mortality and only 0.0034% of seeds in the forest interior and 0.41% of those in the forest edge survived to reproduction. The decrease in the survival probability with decreasing offspring size was more conspicuous in smaller size and in the forest interior than in the forest edge. From these demographic characteristics we examined the adaptive significance of resource allocation to seeds and vegetative propagules in S. palmata.
種生物学会の論文