One new species of Aristolochia, A. singalangensis, from Sumatra is described here. This is the only Malesian species to have the fruit dehiscing from the apex towards the base. Remarks are given for some Asiatic and Malesian species, all belonging to Aristolochia except one to Thottea, on their taxonomy, nomenclature, typification, characteristics for identification, relationship, distribution, etc. The phenomena and significance of aristolochiaceous plants-butterflies relationship have been discussed. Germinated pollen grains have been found in dehisced anthers of open flowers in both Aristolochia and Thottea. Pollination of the Aristolochiaceae has been concisely reviewed.