Geocarpy

Geocarpy is a reproductive strategy in which fruits or seeds develop and mature underground, rather than above the soil surface. It is most notably observed in certain legume species, but occurs in a range of plant groups. In true geocarpy, after fertilization a stalk or peg elongates and penetrates the soil, carrying the developing ovary into the ground. The fruit then forms underground and its seeds mature within the soil, with dispersal often occurring when the soil is disturbed or when the plant decays.

Classic examples are the peanut (Arachis hypogaea) and the Bambara groundnut (Vigna subterranea). In these species, after pollination the flower stalk extends downward, pushing the ovary into the soil where the pod forms and matures underground. The seeds are harvested later from the buried pods.

Geocarpy has evolved independently in several plant lineages and is often associated with specific ecological settings. The subterranean development can offer protection from herbivores, desiccation, and temperature fluctuations and may align seed maturation with particular environmental conditions, such as rainfall. However, it typically reduces seed dispersal potential and may impose strict soil requirements for successful development.

Research on geocarpy contributes to understanding plant adaptation, crop domestication, and the diversity of reproductive strategies in flowering plants. Ongoing studies aim to document additional geocarpic taxa and to uncover the genetic and developmental mechanisms that enable underground fruiting.