Which Bornean pitcher plant gains nitrogen from Hardwicke's woolly bat droppings?

Nepenthes hemsleyana is the Bornean pitcher plant that gains nitrogen from Hardwicke’s woolly bat droppings.

This species has a mutualistic relationship with Hardwicke’s woolly bat, Kerivoula hardwickii. The bats commonly roost inside its upper pitchers, which provide shelter and a relatively stable microclimate. In return, their faeces fall into the pitcher and supply nitrogen that the plant can absorb.

The relationship is an alternative to relying mainly on trapped insects. N. hemsleyana’s upper pitchers have an expanded waxy zone, relatively watery fluid, and reduced visual and chemical prey-attraction features compared with some related species. Their shape also appears suited to bat roosting. A parabolic structure on the rear wall reflects bat calls, potentially helping the animals locate pitchers in dense vegetation.

The nutritional benefit is substantial: research estimates that bat droppings provide about 33.8% of the plant’s total foliar nitrogen. The bat receives more than a feeding station—it gains a sheltered roost. This is why the species is often discussed as a classic example of a carnivorous plant shifting toward a mammal-assisted nutrient partnership.