姜目芭蕉群植物种子解剖学研究及其系统学意义

Seed Anatomy of Species in Banana Families of Zingiberales and Its Systematic Significance

研究了姜目芭蕉群代表植物象腿蕉属象腿蕉(Enseteglaucum)、旅人蕉属旅人蕉(Ravenalamadagascariensis)与蝎尾蕉属Heliconiafaranmansis种子解剖特征。结果表明,象腿蕉无假种皮,种皮分化出表皮、厚壁组织细胞和石细胞层,石细胞仅内切向壁与径向壁增厚;合点区具有合点室与合点堆,内种皮连续;珠孔区有珠孔领和孔盖的分化,珠孔领为同形型,孔盖只由内种皮细胞构成;珠孔区种皮延伸形成种脐腔;外胚乳1层细胞;内胚乳细胞径向延长,细胞内充满淀粉粒。旅人蕉具假种皮,种皮分化出外种皮、中种皮和内种皮,外种皮细胞纵向延长,中种皮为7-9层切向延长的薄壁细胞,内种皮为石细胞型;合点区无合点室,内种皮在此出现缺口,缺口为整体轮廓呈喇叭形的近等径薄壁细胞群填充;珠孔区无珠孔领与孔盖的分化;外胚乳缺,内胚乳发达。蝎尾蕉属的Heliconiafaranmansis种子无假种皮,种皮无分化,由数层体积较小且径向延长并排列为栅栏状的薄壁细胞构成;珠孔端种皮向外延伸,形成类似姜科种子的种阜状结构;无孔盖与珠孔领但具有由果皮形成的硬化盖;合点区与旅人蕉相似;外胚乳约3-4层细胞,细胞壁波浪形弯曲,内胚乳发达。综合作者对兰花蕉(Orchidanhachinensis)和前人对芭蕉群的种子解剖学研究结果。

Seed anatomy of Ensete glaucum (Musaceae), Ravenala madagascariensis (Strelitziaceae) and Heliconia faranmansis (Heliconiaceae) was studied. Seeds of Ensete glaucum comprise seed coat, perisperm, endosperm and embryo, aril absent. Epidermis, sclerenchyma and sclereid are differentiated from seed coat and the sclereid thickened on anticlinal and inner periclinal walls. Chalazal chamber and chalazal mass are well-differentiated but the endotesta is continuous in chalazal region. Micropylar collar and operculum exist in micropylar region. The operculum consists of only sclereid endotesta, and the testa extends and results in a hilum cavity within this region. Perisperm has only one layer of cells while endosperm is massive and abundant in starch grains. Seeds in Ravenala madagascariensis have aril, seed coat includes exotesta, mesotesta and endotesta. The exotesta cells are elongated in longitudinal section and rounded in transverse section, and the cell walls of exotesta are thickened like those in Zingiberaceae. Mesotesta contains 7-9 layers of parenchyma cells which are tangentially elongated and the endotesta cells are sclereids. Chalazal chamber and chalazal mass are absent, and the endotesta is discontinuous and forming a gap. The gap is filled with parenchyma cells which is trumpet-shaped in outline. Micropylar collar and operculum are absent in micropylar region. Perisperm is not differentiated but endosperm is well-developed. Aril is absent in the seeds of Heliconia faranmansis and the seed coat without differentiation consists of a few layers of parenchyma palisade cells which are small in size and radially elongated. Seed coat extends outwards and forms a caruncle-like structure. Micropylar collar and operculum are not differentiated but a sclerotic plug is formed from endocarp. Chalazal chamber and chalazal mass are absent, and the endotesta is discontinuous and filled with parenchyma cells. There are about 3-4 layers of perisperm cells, the cell wall of which is curved. Endosperm is massive and rich in starch grains. Based on the studies on seed anatomy of the three representatives and of Orchidantha chinensis, and the previous studies, the characteristics and patterns of seed anatomy in banana families of Zingiberales are discussed.