The genus Dischidia comprises approximately 80 species of succulent epiphytic vines native to Southeast Asia. The genus is divided into three sections based on leaf morphology: section Dischidia with laminar leaves, section Conchophylla with shell-shaped leaves, and section Ascidifera with pitcher-leaves. Many species of all three sections frequently occur in the nests of arboreal ants, and ants use the leaves of section Ascidifera and section Conchophylla as nesting sites. Both shell- and pitcher-leaves develop via differential growth of the adaxial and abaxial leaf surfaces, leading to the hypothesis that pitcher-leaves evolved from shell-leaves via increased curvature of the leaf during development. I present combined cladistic analysis of morphology and sequences of the second intron of the nuclear gene Leafy. The results support the monophyly of Dischidia s.l. and the sister-group relationship of Dischidia and Hoya. The segregrate genera Dischidiopsis, Oistonema, Conchophyllum, and Leptostemma should be included in Dischidia s.l. while the monotypic genus Micholitzia should be excluded. The analysis also shows that Dischidia species which have both alternate and opposite phyllotaxy form a clade, a grouping which has never been formally proposed. Section Conchophylla plus section Ascidifera form a monophyletic group, consistent with the evolution of pitcher-leaves from shell-leaves.

Key words: ants, Asclepiadaceae, Dischidia, epiphytes, Leafy, systematics