Abstract
Both species belong to the same genus and resemble each other. They migrated and became naturalized to Japan separately 100 and several decades or more ago. Area with dense distribution of Veronica hederaefolia is very limited in contrast to that of V. persica. Reproductive ecology in both species was studied and the relationship between the ecological conditions and distribution was discussed in this paper.
Both species reproduce autogamously (Table 1) and allogamously, and do not produce seeds by parthenogenesis (Table 1).
Some young plants of both species were collected from volunteer communities in Haru and Harada (A and B communities respectively) in Chikushino. The two locations were 8km apart from each other. The A and B plants were grown and selfed seeds “SA and SB” were obtained by bagging while open pollinated seeds “Open A” were collected from the A communities. Crossed seeds “F1 (A×B)” were obtained by artificial crossing in the respective species.
The four kinds of seeds of each species were sown and the growth ability of the plants was compared (Table 2). No significant differences were recognized in the growth rate and seed numbers in the four groups of V. persica plants, whereas in the case of V. hederaefolia the values of these parameters were significantly reduced in the SA and SB plants compared with the F1 (A×B) plants. Inbreeding depression was recognized. This species is considered to show unfavorable characteristics for survival, propagation and colonization when individuals grow in isolation.
Thirty seven species of insects belonging to 3 orders were collected on the flowers of both plant species in the A communities (Table 3).
