J Syst Evol ›› 1983, Vol. 21 ›› Issue (1): 76-78.

• Research Articles • Previous Articles     Next Articles

On the Identity of Trirostellum Z. P. Wang et Q. Z. Xie

Xue Xiang-Ji, Mao Jie-Qi, Zhang Zhi-Ming, Hsu Ping-Sheng   

  • Published:1983-02-18

Abstract: According to Wang and Xie, their recently published genus Trirostellum is distinguished from its allied genera by a number of characteristics: (1) the stamens with their filaments coherent into a central column; (2) the female flowers possessing rudimentary stamens; (3) the ovary 3-celled, with one ovule in each cell; (4) the fruits dehiscent, 3-rostrated at the apex; (5) the fruits possessing persistent perianth; (6) the seeds tuberculate and winged. However, upon a careful comparison of Trirostellum yixingensis Z.P. Wang et Q. Z. Xie, the type species of Trirostellum with Gynostemma pentaphyllum (Thunb.) Mak., the type species of Gynostemma Bl. and some other species of Gynostemma as well,we have found that the representatives of the above two genera are identical in most of the important diagnostic characteristics except that the fruits of the former genus are dehiscent with three long beaks at the apex, while the fruits of the latter genus are indehiscent with very short beaks. Besides, results obtained from chromosome counting haove shown that the somatic chromosome number of Trirostellum yixingensis is 2n=22, while that of Gynostemma pentaphyllum is 2n=28.Yet these morphological and chromosomal differences seem not sufficient for generic demarcation. We, therefore, suggest that Trirostellum bereduced to a sectional or subgeneric rank of Gynostemma Bl.