喉毛花的胚胎学研究

本文首次系统地记载了喉毛花属的胚胎发育过程，并以此为依据讨论了该属的分类等级和系统位置。喉毛花花药四室；药壁发育属双子叶型；绒毡层单型起源，细胞具单核，属腺质绒毡层；一层中层细胞；花药壁表皮层宿存，纤维状加厚和膨大；药室内壁减缩。小孢子母细胞减数分裂为同时型，四分体的排列为四面体型；成熟花粉为3-细胞型。子房为2心皮、l室，典型的侧膜胎座，胚珠8列，胚珠胎座靠近两心皮腹缝线。薄珠心，单珠被，倒生胚珠。大孢子母细胞减数分裂形成的4个大孢子呈直列式排列，其中合点端的大孢子具功能。胚囊发育为蓼型。极核在受精前融合为次生核。反足细胞宿存、分裂为8～12个，每个细胞均多核和异常膨大，反足细胞形成的吸器明显。异花传粉，珠孔受精。花粉管通过破坏一助细胞进入胚囊。受精作用属于有丝分裂前配子体融合类型。胚乳发育为核型，每核含2～3核仁。胚胎发育为茄型酸浆I变型，成熟种子胚只发育至球形胚阶段。反足细胞在合子分裂之后才开始退化，在胚的发育过程中反足细胞在胚乳层之外形成一层染色深、类似“外胚乳”的结构。比较喉毛花、龙胆属、假龙胆属以及肋柱花属的胚胎学特征表明喉毛花与假龙胆属的亲缘关系最近，在分类等级上作为一个独立的属较为合适，在系统位置上它比假龙胆属更为原始。

THE EMBRYOLOGICAL STUDIES OF COMASTOMA PULMONARIUM (GENTIANACEAE)

This paper describes embryological characters of Comastoma pulmonarium (Tur-cz. ) Toyokuni for the first time, with an aim of discussing the systematic position of the genus Comastoma. The development of anther walls conforms to the dicotyledonous type. All tapetum cells origin from the primary parietal cells. The tapetum with uninucleate cells is of secretory type. The epidermis persists while endothecium degenerates. Cytokinesis in the mi-crosporocyte meiosis is of simultaneous type and microspore tetrads are tetrahedral. Pollen grains are 3-celled. The ovary is bicarpellate, unilocular with eight series of ovules and typical with parietal placentation. The ovule is unitegmic, tenuinucellate and anatropous. The embryo sac originates from a single-cell archesporium. The chalazal megaspore in linear tetrad is the functional one. The development of embryo sac is of the Polygonum type. Before fertilization, two polar nuclei fuse into a secondary nucleus. Three antipodal cells persist while divide into 8~12 cells, each of which is multiseriate containing more than 3 nuclei. The size of the antipodal cell is enlarged to be several times bigger than the normal cell. The haustori-um formed from antipodal cells is distinct. Fertilization is porogamous. The pollen tube destroys a synergid to enter embryo sac and discharge the two sperms. One of the sperms fuses with the egg cell to form the zygote while the other with the scondary nucleus to form the primary endosperm nucleus almost simultaneously. The fertilization conforms to premitotic syngamy type. The development of the endosperm is of the Nuclear type. The early several divisions of the endosperm nuclei are simultaneous and each nucleus contains 2~3 nucleoli. The embryogeny corresponds to the Physalis I variation type of the Soland type. The antipodal cells form a layer of "out endosperm" just out of the endosperm nucleus layer and degenerate after the division of the zygote. Compared with Gentiana, Gentianella and Lomatogoni-um, Comastoma is embryologically more closely related to Gentianella than to Gentiana and Lomatogonium. It shares more embryological similarities with Gentianella than the other two genera, but differs from Gentianella in some important characters such as ovule curvature, ovule series, placentation and the path of pollen tube. However, these diagnostic characters are usually used to circumscribe the taxon above the generic rank. Therefore, from embryological evidence,Camastama is better bestowed as a generic rank. This genus is more primitive than Gentianella according to evolutionary trends of the embryological characters.