Phylogenetic anatomy of the Cretaceous Cycadophytes.

为了阐明被子植物的起源，我们对白垩纪苏铁类植物进行了解剖学研究。1)Nishida，Harufumi对北海道和千叶县的本尼提塔尔的花进行了组织学和器官学研究。(1)他研究了苏铁总科和苏铁总科的花的确切结构，并阐明了苏铁总科的胚珠被一层单细胞的鞘所包裹。(2)他在苏铁的被膜中发现了管束，这是迄今为止在Bennettitales中从未被检测到的。(3)他还观察了苏铁总节管壁中的维管束，这也是迄今为止在这个目中从未发现的。(4)他提出了一个新的器官学假说，即本氏叶的联囊壁和胚珠鞘起源于本氏叶小羽片的终末节段(Nishida，H.，1991)2)Nishida，Makoto研究了。白垩纪苏铁类的一些营养器官。(1)他回顾了北海道的四种苏铁的组织学，并描述了来自群马县的一种大苏铁为一新属(Nishida et al.，1991)。(2)他还观察了来自北海道的一个石化的叶柄和一个细长的树干，它们与活着的苏铁非常相似。这些发现是日本首次发现石化苏铁。

We have examined anatomy of the Cretaceous cycadophytes as a basic studies to elucidate the origin of angiosperms. 1)Nishida, Harufumi has studied histology and organography of flowers of Bennettitales from Hokkaido and Chiba Prefecture. (1)He has examined exact structure of flowers of Cycadeoidea, a big member of the order, and Cycadeoidella, a small member of the order, and elucidated that the ovules of Bannettitales are enveloped by a one cell-layered sheath. (2)He found out vascular strand in the integument of Cycadeoidella, which has never been examined in Bennettitales so far. (3)He also examined vascular strand in the walls of synangium of Cycadeoidella, Which has also never been known in this, order so far. (4)He has proposed a new organographycal hypothesis that the walls of synangium and ovular sheath of Bennettitales originate in ultimate segments of pinnules of bennettitalean fronds(Nishida, H., 1991).2)NISHIDA, Makoto has examined anatomy of. some vegetative organs of the Cretaceous cycadophytes. (1)He has reviewed histologically four species of cycadeoidean trunks from Hokkaido, and in addition, he described a big cycad trunk from Gunma Prefecture as a new genus(Nishida et al., 1991). (2)He also examined a petrified petiole and a slender trunk from Hokkaido, which closely resemble living Cycad. These findings are the first records of petrified cycads in Japan.