The population of the Primula tosaensis Yatabe var. tosaensis in Oguchi-cho, Isa City, Kagoshima Prefec- ture, Japan, which corresponds to the southern limit of the distribution, was surveyed for the total number of individuals, size composition, and floral heterostyly. The population consisted of 93 individuals, and its dis- tribution area was very limited. The size composition of the individuals was monomorphic, with a peak at a maximum leaf length of about 3 cm, and a relatively small number of individuals with leaf length classes of less than 1 cm. Flowering started at a size of about 2.5 cm in leaf lamina length. Furthermore, a significant model was found between lamina length and the num- ber of flowers, and the number of flowers could be es- timated from leaf size. Of the 56 flowering individuals, 34 were of the long-style flower and 22 were of the short-style flower, allowing for cross-pollination among the different style types. However, the relative- ly small number of un-flowered small individuals sug- gests that there may be a lack of continuous recruit- ment of new individuals by seed propagation.

鹿児島県伊佐市におけるイワザクラ南限域個体群 のサイズ構成と花柱型(川西基博・柳田光久)