苏铁属叉叶苏铁亚组国产种类的羽片比较解剖学研究

为了比较苏铁属各分类群的异同并为其分类工作提供重要的理论依据,采用解剖学的方法,观察并分析了国产叉叶苏铁亚组5个分类群:叉叶苏铁、多羽叉叶苏铁、长柄叉叶苏铁、多歧苏铁和德保苏铁的羽片横切下皮层厚壁细胞、海绵组织含晶细胞、叶缘、中脉区及韧皮部形状、分泌道等特征和羽片小叶柄纵切中管胞类型、直径大小及管胞壁纹饰特征。结果表明:叉叶苏铁和多羽叉叶苏铁解剖特征非常接近;长柄叉叶苏铁叶缘弯曲、韧皮部呈"V"形与前二者区分;多歧苏铁中脉区远轴面半圆形、叶缘弯曲部位变厚、先端锐等特征和德保苏铁中脉区远轴面呈较平缓圆弧形,叶缘弯曲部位变薄、先端钝易区分。5个分类群在下皮层厚壁细胞、中脉区具分泌道和小叶柄中管胞等解剖特征方面具有一致性,表明这些分类群可能由共同的祖先演化而来。

Comparative anatomy of the pinnae of native plants of subsect.Stangerioides in Cycas

The study was conducted on the anatomy of comparative pinnae of 5taxa , namely , Cycas bifida , C.multifrondis , C.longipetiolula , C.multipinnataand C.debaoensis , classified in the subsection Strangioides ( T.Smitinand ) D.Y.Wang of Cycas.The results showed that C.multifondis , C.bifida , and C.longipetilula were similar in the shape of midrib region and in the absence of secretory canal , but C.longipetiolula was different from the former two with rolling leaf margin abaxially and " V " shape phloem.And the results also indicated that C.multipinnata with semicircle shape of abaxial midrib region and thickening acute leaf margin could be distinguished fromC.debaoensis with arch shape of abaxial midrib region and thinning obtuse leaf margin.All these taxa shared uniform charateristics of hypodermal sclerenchymatous cells , secretory canal and stracheids , probably indicating that they evolved from a common progenitor.