geocarpy

thumb|upright=1.2|Geocarpy in Spigelia genuflexa thumb|Peanut fruit have formed below the ground.

Geocarpy is "an extremely rare means of plant reproduction", in which plants produce diaspores within the soil. This may occur with subterranean flowers (protogeocarpy), or from aerial flowers, parts of which penetrate the soil after flowering (hysterocarpy). It has evolved as an effective means of ensuring a suitable environment for the plant's offspring.