摘要
为探讨厚壳树亚科在紫草科中的系统位置 ,用扫描电子显微镜研究了国产厚壳树亚科Ehre tioideae的厚壳树属Ehretia、轮冠木属Rotula和基及树属Carmona 3属 1 2种植物的花粉形态 ,其扫描电镜资料属首次报道。从本文并结合文献报道的双柱紫草属Coldenia的花粉资料 ,可得知该亚科花粉为长球形、近球形 ,稀球形 ,赤道部位具有不同程度的膨大 ;萌发孔类型为三孔沟和三拟假沟二者交替排列 ,稀具三孔 ;外壁表面具微弱的小穿孔 ,稀光滑或皱波状纹饰。厚壳树亚科Ehretioideae与破布木亚科Cor dioideae在花粉特征上有非常明显的区别 ,例如 ,花粉形状、萌发孔数目和类型等都不同。因此 ,厚壳树亚科不应作为破布木亚科的异名 ,而应作为紫草科Boraginaceae中的一个独立的亚科。厚壳树亚科花粉的萌发孔和形状在演化水平上都高于破布木亚科 ,表明破布木亚科是紫草科中最原始的类群 ,厚壳树亚科次之 ;但有些花粉特征显示出厚壳树亚科与破布木亚科二者在紫草科中仍属比较原始的类群 ,例如 ,它们的花粉体积比较大 ,在赤道部位不缢缩等。厚壳树亚科的轮冠木属Rotula的花粉具三孔 ,与破布木亚科的花粉有相似之处 ,这表明厚壳树亚科与破布木亚科之间可能有一定的亲缘关系。
Pollen morphology in ten species of Ehrelia and each one species in Rotula and Carmona of the Ehretioldeae, Boraginaceae, was observed under scanning electron microscope (SEM). Pollen grains are prolate or subspheroldal, rarely spheroidal, more or less enlarged In the equatorial region, elliptic to subrhombic in equatorial view, and hexalobate-circular or obtuse-triangular in polar view; the apertures are 3-colporate alternated with 3 pseudocolpolds, and rarely 3-porate; the exine is faintly microperforate, rugulate or psilate. The results show that the subfamily Ehretioldeae is distinctly different from the subfamily Cordioldeae in pollen morphological features, such as the pollen shape, the aperture number and type, and hence support the treatment of them as two independent subfamilies. Some pollen morphological features, such as the rather large size of pollen grains and the equatorial region not being constracted, suggest that both Ehretioldeac and Cordioldeae might be primitive groups in the Boraginaceae, although the pollen grains in Ehretioideae seem to be of a higher evolutionary level than those in Cordioideae as, shown by their shape and aperture features, and thus indicate that the former subfamily might be more advanced Than the latter. Pollen grains in the genus Rotula in Ehretioideae are 3-porate, implying the possible close relationship between Ehretioideae and Cordioldeae.
出处
《植物分类学报》
CSCD
北大核心
2003年第3期209-219,共11页
Acta Phytotaxonomica Sinica
基金
国家自然科学基金 ( 3 9970 0 45 )
北京市自然科学基金 ( 5 992 0 0 5 )资助项目~~
关键词
紫草科
厚壳树亚科
花粉形态
系统学
Ehretioideae
Cordioideae
Ehretia
Rotula
Carmona
Coldenia
pollen morphology
systematics
