Reproductive Biology of Plantago: Shift from Cross- to Self-pollination

The breeding systems of an obligate outbreeder (Plantago lanceolata)and an obligate inbreeder (P. patagonica) were compared. Outbreedingin the former and inbreeding in the latter species is achievedby self-incompatibility and preanthesis cleistogamy, respectively.The difference in breeding system is accompanied by a differencein the pollen output, pollen to ovule ratio, stigma and anthersize, and seed weight. P. ovata, a third species known onlyin cultivated form, is intermediate. This species has two typesof plants, some of which are protogynous and others where stigmareceptivity and anther dehiscence synchronize. Although thedifferences between the two intraspecific variants are not large,they nevertheless suggest that the species is in evolutionaryflux. Domestication is known to have modified the breeding systemin many crop plants and there is evidence that, in P. ovata,a start in this direction has already been made. Plantago lanceolata, P. ovata, P. patagonica, protogyny, anther, stigma, pollen to ovule ratio