Aristolochia yachangensis, a new species of Aristolochiaceae from limestone areas in Guangxi, China

Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang, a new species from limestone areas in Guangxi, China, is described and illustrated. It is morphologically most similar to A. fangchi Y.C.Wu ex L.D.Chow & S.M.Hwang, A. petelotii O.C. Schmidt and A. championii Merr. & Chun in shape of leaf blade, anther, gynostemium and inflorescence on old woody stems. However, it can be easily distinguished from the latter by shape of inflorescence, length of upper and lower portions of perianth tube, colour of the limb and throat. A table and a key to distinguish the new species from other morphologically similar Aristolochia species are also provided.