Hydnophytum formicarum, commonly called a "Baboon's head" or "Ant plant", is an epiphyte native to Southeast Asia and is considered critically endangered in Singapore.

Flowers are four-merous, white, and occur in groups of 3–10, which then yield orange, fleshy fruits 6–7 mm in diameter Ants that have been reported to be inhabiting this myrmecophyte include: Iridomyrmex cordatus, Camponotus spp., Crematogaster spp., Monomorium spp., Tapinoma spp., and Paratrechina spp.

[4] The cells lining the nest show layers enriched with endoplasmic reticulum, dictyosomes, mitochondria and higher levels of enzymes associated with absorptive surfaces.

[6] Studies on other epiphytes, such as Piper fimbriatum, have shown that the nutrients are absorbed by the walls of the caudex and domatia, and then move along a chemical gradient via the phloem and bulk flow to other parts of the plant.

A number of studies were done to investigate the ant plant in terms of morphology, mutual relationships, occupancies, physiology and ecology to understand the mechanisms that allow it to function the way it does.

A compilation of such experimentation done by a variety of researchers was created by Camilla R. Huxley in which she investigated and analyzed all information discovered about the Hydnophytum formicarum to determine whether presence of ants were directly beneficial to plant conditions.

Results found that radioactivity was mainly seen on the warted cavities, the area with highest absorption rates, and vascular tissues of the stem, showing translocation of materials by the plant.

It was concluded that Huxley's hypothesis was supported and that compounds fed to the ants could be radio isotopically seen to be deposited and readily absorbed through the plant.