Dischidia

Dischidia is a genus of plants in the Milkweed family, Apocynaceae. They are epiphytes native to tropical areas of China, India and most areas of Indo-China.
Most Dischidia grow in arboreal ant nests of different species and some have developed a symbiotic relationship where the plant has developed modified leaves to either provide housing or storage. Of these there are two types of modification to the leaves. Three species develop bullate leaves which are hollow root-filled structures.