Research of characteristics of leaf epidermis for apocynaceae.

With Gymnema sylvestre(Retz.)Schult.as a control,we researched the characteristics of leaf lower epidermis for species which traditionally belonging to three subfamilies of Apocynaceae under SEM.(1)The characteristics of leaf lower epidermis were diverse in some degree for 25 species of Apocynaceae.Trichomes occurred in some species.Filamentous waxy occurred in cuticula surface of some species;Stomata size were different too;The shape of the outer and the inner stomata ledge have been divided into comparatively smooth and sinuolate types;The shapes of polar regions of stomatal guard cells have two types with T-thicker and non-T-thickening types;The joint cells between the outer stomatal ledge and epidermis could be divided into depression and continuous types.These characteristics of the leaf epidermis have important reference value for the classification of intergeneric and interspecific even difficult taxa in Apocynaceae.(2)They were similar in leaf epidermis stomatal types,the shape of the outer and the inner stomata ledge for most 25 species of Apocynaceae,but it existed higher diversity in decoration of lower epidermis and outer stomatal cuticle which have much difference in intergeneric and interspecific species.(3)The highly degree of similarity in the shapes of stomata,stomatal outer cuticle characteristics and the outer stomata ledge between G.sylvestre and W.calophylla was observed,and it could be deduced that they may have close relationship between the two species.The position of plant systematics for some species of Asclepiadaceae and Apocynaceae should be implemented further research.(4)The results of this research supported the viewpoints that genus of Hunteriashould be separated from Trib.Melodineae as a single Trib.,and genus of Cerberaseparated from Trib.Rauvolfieae.But it could not supported the viewpoint that Alstonia scholaris and Winchia calophylla were belonged to genus of Alstoniain new classification method.