中国木犀属植物叶脉形态及其分类学意义

Leaf venation of Osmanthus(Oleaceae)from China and its taxonomic significance

关键词:  叶片脉序  木犀属  中国

Key words:  leaf venation  Osmanthus   China

摘要:

观察了中国木犀属植物4组19种叶脉形态。主要分析木犀属植物叶片脉序走向,脉序为环结曲行或半直行羽状脉。二级脉急转曲行或半直行,叶脉分支一般为4级,少数5级。盲脉1～2次分支,少数3次或不分支。仅柊树叶缘末级脉汇合成边脉。部分叶缘具齿,叶缘齿性状不稳定,因其内主脉不同而在本属种间表现出一个连续的变异过程。圆锥花序组与李榄属和木犀榄属从叶片脉序特征方面表现出较近的亲缘关系。四个组的叶脉形态在演化上关系上与花粉形态表现相一致。编写了叶片脉序特征分种检索表。

Abstract:

Leaf venation of 19 species from 4 sections of the genus Osmanthus were investigated. Venation patterns are brochidodromous or semicraspedodromous. The secondary veins are abruptly curved or branched,usually 5～12 pairs,occasionally up to 16 pairs. Tertiary veins are percurrent and randomly reticulate,occasionally percurrent or admedial. Highest vein order is 4° or 5°. The veinlets are simple or one to twice branched. Only the leaf of O.heterophyllus has fimbrial vein. Some species have leaves with teeth along the margin,and the morphology of the teeth are unstable. The primary veins in the teeth of different species show a series of variations among the Osmanthus species. The leaf venation characters revealed the evolutionary relationships of sect.Osmanthus,sect.Siphosmanthus,sect.Leiolea, and sect.Linocieroides. sect.Leiolea further displayed affinities with Linociera Sw.and Olea Linn. A key to the species of Osmanthus based on leaf venation characters is presented.