芡的花部解剖结构和发育的研究

THE ANATOMICAL STRUCTURES AND FLORAL DEVELOPMENT OF EURYALE FEROX SALISB

芡(Euryale ferox Salisb.)花柄具星散维管束,无形成层。萼片有栅栏和海绵组织分化,花瓣较萼片简单,外轮雄蕊瓣化有附属物,内轮者正常。花原基自混合芽的近叶腋处产生,花器向顶顺序发育。心皮上部有子房沟(ovarian canal)。花轴顶端留有突起。作者认为芡花部显示出原始特性,它与王莲属(Victoria)、睡莲属(Nymphae)、萍蓬草属(Nuphar)亲缘关系相近,与莲属(Nelumbo)、莼菜属(Brasenia)差别较大。

The pedicel of E.ferox possesses closed,scattered vascular bundles and contains no cam- bium.Four again air canals are well developed.Mesophyll of sepal is differentiated into pali- sade and spongy parenchyma.Petal is simpler in structure than that of sepal with no palisade tissue differentiated.Stamens show a wide varity of shapes;those in the outer whoels are usually petatoid while the inner whorls are of the conventional type bearing four-loculate anthers.Ovary is inferior,multicarpellary and syncarpous with laminar plancentae in each locule.The flower primo;dium grows out from the mixed bud.It is enveloped by an axillary scale.The preliminary indication of floral initiation is the periclinal divisions of the second layer of the shoot apex which is closer to the leaf base.By the time a flower primordium be- comes 465μm high,the floral parts begin to arise in a continuous acropetal sequences,namely: sepals,petals,stamens and carpels successively with initiation of their primordia by periclin- al divisions of the second or third layer on the flank of the floral apex respectively.By the fact that the growth of the outer layered cells of the receptacle is faster than those of the inn- er ones,an epigynous flower and an inferior ovary is thus to be formed. The ventral margin of the carpel has become conduplicately appressed and fused in the lower portion,while the upper part has not been fused,an ovarian canal is appeared from top of the ovary.There is no differentiation of a style.A central receptacular core is found among the carpels. On the basis of anatomical and developmental studies of the floral organs,we suggest that Euryale ferox exhibits a number of most primitive features,such as petaloid stamens,ca- rpel with ovarian canal,elongated receptacle,prominent residual floral apex and laminar placentation.The development of floral parts and characteristics of ovary indicate that genus Euryale is much more similar to Victoria,Nymphae and Nuphar than to Nelumbo and Bra- senia.