土圞儿属和旋花豆属(豆科)的叶表皮特征及其系统学意义

摘要

Nineteen leaf epidermis samples representing six species in Apios and two in Cochlianthus were examined for the first time using both light microscopy and scanning electron microscopy.Leaf epidermal characters of these two closely related genera,such as shape of cells,pattern of anticlinal walls,cuticular membrane and wax ornamentation,are usually stable within species and thus of great significance in understanding the relationships between and within genera.The results indicate that(1)A.gracillima Dunn should be recognized as a distinct species,not a variety of Apios delavayi Franch.,(2)the division of Apios into two subgenera is unreasonable,and(3)Apios and Cochlianthus are retained as two distinct genera.%应用光学显微镜和扫描电子显微镜观察了豆科Leguminosae土圞儿属Apios和旋花豆属Cochlianthus植物的叶表皮特征.在光学显微镜下,大多数种类的叶表皮细胞形状(表面观)为不规则型,垂周壁式样为浅波状或波状,只有一个种--Apios gracillima Dunn叶表皮细胞为多边形,垂周壁式样为较平直.在扫描电子显微镜下,多数种类的叶片蜡质纹饰通常为片状或颗粒状,一些种叶表皮未见蜡质纹饰;气孔器外拱盖内缘通常为浅波状或近平滑.在这两个属内,上述叶表皮特征在物种内较稳定,因此对于解决属内种问和属间关系有一定的系统学意义.本研究得出以下结论:(1)A.gracillima叶的上表皮细胞为多边形,垂周壁平直或弧形,A.delavayi Franch.叶的上表皮细胞为不规则形,垂周壁波状,二者存在明显差异,因此A.gracillima应处理为一独立的种,而不是A.delavayi下的一个变种;(2)A.priceana B.L.Rob.在叶表皮细胞形状、垂周壁式样、气孔器类型和蜡质纹饰形态等方面与土圞儿属中其他种不存在显著区别,因此土圞儿属内两个亚属的划分是不合理的;(3)土圞儿属多为5或7小叶,无毛或近无毛,叶表皮细胞垂周壁波状或近平直,而旋花豆属3小叶,密被柔毛,叶表皮细胞垂周壁浅波状,本文支持它们为两个独立的属的分类处理.