不同生境下十七种藓类植物叶的比较解剖学

Comparison of Leaf Structures among Seventeen Moss Species Collected from Different Habitats

使用石蜡切片法,对不同生境下的17种藓类植物的叶片进行了解剖观察和比较分析,结果表明不同种类的藓类植物在中肋导水主细胞的有无、厚壁细胞是否分化、中肋细胞层数及细胞密度、叶片细胞层数、叶表附属物、叶片细胞密度等方面存在显著差异。藓类植物叶的解剖结构具有生态适应意义,旱生环境下的藓类植物,叶片细胞胞壁具不同程度的增厚,有些藓类植物叶片具附属结构,藓类植物中肋的有无,反映了对水分吸收和运输方式的不同。例如,荫湿生环境下的羽枝青藓Brachythecium plumosum,其中肋细胞胞壁较薄,无导水主细胞和副细胞的分化,也没有厚壁细胞分化,能够在阴湿环境下吸收水分和养分;钝叶匍灯藓Plagiom niumrostratum具有与旱生藓类植物相似的中肋结构,叶片较厚,中肋具导水主细胞,中肋背面具厚壁细胞,这些特点使该种藓类植物能够分布于间隙性干旱胁迫的环境中;水灰藓Hygro-hypnum luridum叶片纤细柔弱,仅1层细胞,细胞胞壁薄,叶表无附属结构,中肋细胞层数少,无导水主细胞分化,也没有厚壁细胞,这些特点使得水灰藓能够生长在水生环境中;东亚小金发藓Pogonatum inflexum和波叶仙鹤藓Atrich umundulatum的叶腹面覆盖着栉片,东亚砂藓Racomitrium japonicum、大羽藓Thuidium cym-bifolium、福氏蓑藓Macromitrium ferriei、东亚短颈藓Diphyscium fulvifolium、扭口藓Barbula unguiculata和角齿藓Ceratodon purpureus的叶片表面有乳头状突起或疣状物,这些附属结构使它们能够适应于旱生的环境中。

The leaf structures of 17 mosses collected from different environmental conditions were transeeted and compared by means of paraffin wax section. The results showed that speeies vary much among the features such as the absence or presence of hydrome cells, the differentiation of steroid cells, the numbers of cell layer, the density of the eostae, the numbers of laminal cell layer, etc. The leaf anatomical structures of the mosses are of ecological adaptation to their habitats. The mosses under dry conditions often have thickened laminal cell-walls on the surfaces, and some of them have appendieulate structures. The differentiation states of costae indicates the ways they absorb and transport water, and their ability adapting to the dry conditions, which was elucidated by the following examples： Brachythecium plumosum, because of its thin cell-walls in the costae and the absence of hydrome, assistant and steroid cells, can absorb water and nutrition under shady and moist conditions; Plagiomnium rostratum, though often grows in shady and wet condition, has hydrome and steroid cells, a feature similar to those of xeric mosses, which endows it to grow in the conditions with periodical drought stress during its life cycle; Hygrohypnum luridum is characterized by its slender leaves with only one layer of cells, the thin cellwalls, the absence of fdaments on the leaf surface, and the fewer layer cells in the costae, the absence of hydmme and steroid cells. These feattrres make it adaptable to aquatic environments. For Pogonatum inflexum and Atrichum umhdatum, their ventral surfaces covered with lamella, while for Racomitrium japonicum, Thuidium cymbifolium, Macromitrium ferriei, Diphyscium fulvifolium, Barbula unguiculata and Ceratodon purpureus, their leaves are strongly mammillose or papillos. Such appendiculate structures made them adaptable to dry conditions.