| Abstract: | A comparative anatomical study on the secondary phloem of 5-genera, 10 species in Celastraceae was carried out. Based on the phloem structure characters, 3 phloem types were observed. In type Ⅰ , as seen in 5 species of Euonymus, the sieve-tube elements have more inclined end walls and numerous sieve areas (compound sieve plates), phloem rays are almost uniseriate. Type Ⅱ is seen in Celastrus and Tripterygium. It has relatively short sievetube elements, slight inclined end wall and sparse number of sieve areas: the phloem fiber is not lignified and ray is multiseriate. Type Ⅲ is observed in Dipentodon and Perrottetia, the sieve-tube elements are with simple sieve plate, the end wall is almost transverse, there are sclereid and fiber groups in the nonfounctional phloem, and phloem rays are uniseriate or biseriate. |
