Abstract:Flower location． sex ratio and numerical variation of the flower parts of Woonyoungia septentrionslis (Dandy) Law，an endemic species in China，were investigated by random sampling trees from natural population of Woonyougia septentrionalis in Mulun Village，Huanjiang County (Guangxi Province). Although most of the flowers (90％) were terminal as previously described，a small fraction (10％) were found to be axillary，which was not recorded previously．The ratio of male to female individuals was 1.2 1:1 Statistic results from 600 flowers iD 20 individuals from introduced trees in South China Botanica1 Garden and from natural population iD Mulun show that the number of flower parts， except the number of thecae per stamen an d the number of ovules per carpel，is variable．The variations are：2—6 tepals in one or two whorls．81—1 52 stam ens in male flowers，two whorls oftepals， 2—4 in the outer whor1．5—13 in the inner．and 3-8 carpels in fema1 flowers．Two thecae in each stam en， an d two ovules iD each carpel are the only stable characters．Great vailation in flora1 characters indicates that this species possesses high genetic diversib'．The phyIogenetic significance of co-occurrence of axillaD,and term inal fowers．the heterobathmy of flora1 characters，an d the tenability of the genus m Jonyoung~a are~iscussed