石香薷（唇形科）的胚胎学研究

石香薷(Mosla chinensis Buch.-Ham.ex Maxim.)花药壁发育属双子叶型。花药具4个小孢子囊;腺质绒毡层,细胞具2～4核,有3至数个核仁;初生造孢细胞直接行小孢子母细胞的功能,在小孢子囊中成单列。花粉母细胞减数分裂后胞质分裂为同时型;小孢子四分体呈四面体形,也有左右对称形,成熟花粉具2细胞。胚珠倒生,单珠被,薄珠心,大孢子四分体线形排列,功能性大孢子位于合点端,少数为合点端第二个细胞。胚囊发育属蓼型,珠孔区近卵圆形,比合点区稍短,合点区较狭窄。胚胎发生属柳叶菜型。细胞型胚乳,珠孔吸器为单孢3核,合点吸器为单孢2核。种子无胚乳,种皮由珠被发育。石香薷雌雄配子体的发育、胚胎发生及胚乳形成,与紫苏属的Perilla ocimoides几乎完全一致。不同点仅在于石香薷在2-细胞花粉时,药室内壁细胞切向伸长,壁尚未发生纤维状加厚(P.ocimoides药室内壁细胞径向伸长,胞壁纤维状加厚),珠孔吸器为单孢3核(P.ocimoides为单孢4核)。胚胎学显示石荠苎属与紫苏属有密切的亲缘关系。

EMBRYOLOGICAL STUDY ON MOSLA CHINENSIS (LAMIACEAE)

The formation of microspores and megaspores, the development of male and female game-tophytes, the embryogenesis and the development of endosperm were studied in Mosla chinensis Buch.-Ham. ex Maxim. (Lamiaceae). The development of anther wall was of the dicotyledonous type, of anthers the 4-sporangiate, and that of the tapetum was of the glandular type, of 2 ~ 4 cell nuclei. The primary sporogenous cells functioned directly as microspore mother cells and were arranged in a single row in a microsporangium. The cytokinesis in meiosis of the microspore mother cells was of the simultaneous type. Tetrads were tetrahedral, but sometimes isobilateral. Mature pollen grains contained two cells. Ovules were anatropous, unitegmic and tenuinucellate. The tetrad of megaspores was linear shaped, with the first or rarely the second cell from the chalazal end being functional. The development of embryo sacs belongs to the polygonum type. The micropylar region of the mature embryo sacs was nearly ovate and slightly shorter than the narrowed chalazal region. The embryogenesis was of the onagrad type. The endosperm was cellular. The micropylar haustorium was unicellular with 3-nuclei and the chalazal haustorium was unicellular and 2-nucleated. Seeds were exalbuminous and seedcoat is developed from the integument. The ovary wall developed into pericarp. The embryological characters of Mosla chinensis were mostly consistent with those of Perila ocimoides Linn. However, the cells of the endothecium were elongated and not fiberized at the 2-celled pollen stage in the former,whereas radially elongated and fiberized at this stage in the latter. Furthermore the micropylar haustorium,though unicellular in both, was 3-nucleated in the former and 4-nucleated in the latter. Unfortunately, there is no information of the function and arrangement of the primary sporogenous cells in Perilla, available for comparison. The embryological data so far available infer that the genus Mosla is closely related to Perilla.