Cucumis humifructus
Cucumis humifructus, the aardvark cucumber or aardvark pumpkin, is a species of cucumber from southern and tropical Africa which fruits underground. It is a prostrate vine up to in length. It is reliant on the aardvark to eat the fruit in order to spread and re-bury its seeds. The species was described in 1927, with the name spelling "humofructus", but this is corrected to C. humifructus following the International Code of Nomenclature for algae, fungi, and plants.
Description
Cucumis humifructus is thought to be the only Cucumis species having geocarpic fruit. The vines of the plant initially develop their fruit above ground on stalks which then bend and push back under the ground. The fruit then grows at a depth of between.Most cucurbits have a single tendril at each node, but C. humifructus has 2 to 8, to give it the leverage needed to bury the young fruit. It develops a tough skin which is water-resistant, and can remain intact for months without decay. The plant grows as a trailing herb from in tropical Africa and in southern Africa.
It is the only fruit eaten by aardvarks, which otherwise feed exclusively on ants and termites. Aardvarks eat the fruit for its water content, and propagate the seeds through their faeces, which are then buried by the animals. Due to the depth at which the fruit ripen, the seeds are unable to germinate without assistance, and C. humifructus is completely reliant on aardvarks to uncover their fruit. This plant may be the reason why the aardvark is the only mammal feeding on ants and termites that has retained functional cheek teeth.