In order to better understand variation in cambium in lianas in Taiwan and to aid identification of liana species we examined the stem structure of ten species of lianas belonging to the family Fabaceae. Samples were collected mainly from southern and eastern Taiwan and were selected from plants with different stem diameters in order to compare the structural similarities of plants. The results showed that cambium had a normal appearance and stems were round in Caesalpinia bonduc (L.) Roxb. Caesalpinia crista L. and Caesalpinia minax Hance. We noted a combination of furrowed xylem and dissected xylem in Bauhinia championii (Benth.) Benth. shallowly furrowed xylem in Acacia caesia (L.) Willd. Centrosema pubescens Benth. and Mimosa diplotricha C. Wright ex Sauvalle a combination of flattened stem and interxylary phloem in Entada koshunensis Hayata & Kaneh. and Entada phaseoloides (L.) Merr. and a combination of external vascular cylinder and flattened stem in Pueraria montana (Lour.) Merr. Of these lianas three species -A. caesia B. championii and C. crista -experienced two distinct developmental growth phases. We concluded that variations in cambium and xylem deposition are associated with the size of the stems. Medullary bundles occurred in the pith of P. montana an observation that has not previously been recorded. We present the first description and photographs of these bundles and the external vascular cylinder in the pith and it is recommended that further study of this species be conducted.