SIZE-DEPENDENT REPRODUCTION IN AUSTRALIAN ALPINE RANUNCULUS

The effect of plant size on reproduction in four species of alpine Ran unculus (R. muelleri, R. dissectifolius, R. graniticola and R. nophoph ilus) was investigated in two sites over two seasons in the field on a total of 190 plants. The effects of plant size (number of leaves) and number of flowers on the number of anthers, ovules and seed per flowe r and per plant were determined. There was a positive relationship bet ween several measures of reproduction and plant size in all four speci es, indicating that reproduction is size-dependent. All the results in dicate that the main factor controlling the amount of seed produced by alpine Ranunculus is the size of the plant. Specifically, bigger plan ts produced more seed by producing more flowers, not by producing more ovules per flower, or higher seed set per flower. Correspondingly, bi gger plants produced more anthers by producing more flowers, rather th an by producing flowers with more anthers. The total number of seeds p roduced by a plant was directly proportional to plant size in the four species. Therefore, reproductive effort should not vary with plant si ze in the four species.