Abstract:

Geocarpy and amphicarpy are two special types of fruiting modes in angiosperms, and they occur mostly in terrestrial herbaceous plants. Geocarpous and amphicarpous species often occur in unstable habitats, where water or light is limiting, soil disturbance is frequent and environmental fluctuations are high. These two types of fruiting modes are important plant ecological adaptations that evolved via natural selection. The adaptive advantages of geocarpy include high survivorship of offspring in the favorable parental microhabitats, maintenance of seed viability in extreme environments, escape from herbivory and damage by fire and increase length of the developmental period of fruits. Amphicarpy is ecologically significant in that it reduces competition among siblings within the population, maintains and increases the size of the population in situ and increases the adaptability and evolutionary plasticity of the species. Thus, these two fruiting modes are considered adaptive strategies of species to biotic and abiotic factors of the environment. However, their potential evolutionary disadvantages include limitation of seed or fruit dispersal, influence on gene transfer and thus population genetic structure and increase of population fragmentation and of reproductive costs, all of which can greatly impact the distribution of species, population increase, migration, fitness and life history evolution. Geocarpy has been reported in about 24 families and 57 genera and amphicarpy in 13 families and 34 genera of angiosperms. Moreover, both types of fruiting modes occur in species of Asteraceae, Brassicaceae, Fabaceae and Scrophulariaceae. Phylogenetically, geocarpy occurs in the magnoliids, monocots and eudicots and amphicarpy in both monocots and eudicots, but neither mode has been reported in the basalmost angiosperms (ANITA clades).

Key words: amphicarpy, ecological adaptation, evolutionary restriction, geocarpy, phylogeny, reproductive traits