中国29种和泰国1种卷柏科植物的叶形态学研究及其分类学意义

利用光学显微镜和体视显微镜对卷柏科Selaginellaceae中国产29种和泰国产1种植物的叶形态进行了宏观和微观观察。结果表明卷柏科植物在叶形态学方面表现出较高的一致性。(1)叶多为二形, 罕为一形, 无叶柄, 叶二形者侧叶多大于中叶, 外展或斜上, 中叶贴生于腹面茎上, 交互覆瓦状排成4列, 叶一形者则在茎上作螺旋状排列。(2)侧叶与中叶上表皮细胞形态相似, 近等径方形或长方形, 垂周壁平直、弓形或波状; 侧叶与中叶下表皮细胞形态也相似, 长方形或长条形, 垂周壁波状。(3)气孔类型为无规则型或放射型, 气孔多分布于中叶上表皮和侧叶下表皮中脉处。研究发现, 叶外形、叶表皮细胞形态及气孔分布特征等为中国卷柏科植物种间分类提供了重要的参考依据。 研究的有关种类可以依据下面这些特征进行分类: (1)叶为一形叶或二形; (2)叶在枝上着生为螺旋状或成对交互排列; (3)叶表皮细胞垂周壁为平直、弓形、深波状或浅波状; (4)叶上、下表皮细胞同形或异形; (5)气孔为无规则型或放射型; 以及(6)气孔在中叶和侧叶的上、下表皮上的分布等特征。

Leaf morphology of 29 Chinese and one Thailand species of the Selaginellaceae and its taxonomic significance

Leaf morphology of 29 Chinese species and one Thailand species of the Selaginellaceae was observed under light microscope and stereoscope. Species examined are rather consistent in leaf morphology. (1) Leaves are usually dimorphic, monomorphic only in few species, not petiolate, with the lateral leaves of the dimorphic leaf species larger than the median leaves, spreading outward or ascending, and the median leaves more or less adpressed on the adaxial side of stem, decussate or imbricate, and arranged in four ranks, while the leaves in the monomorphic leaf species spirally arranged. (2) The cells of the upper epidermis of the lateral and the median leaves are similar to each other, sub-isodiametric, tetragonal or oblong, and the anticlinal walls are straight, arched, sinuate or sinuolate; the cells of the lower epidermis of the lateral and the median leaves are also similar to each other, oblong or elongate, and the anticlinal walls are sinuolate. (3) The stomatal apparatuses, which are of anomocytic or actinoid types, are mainly distributed on the midvein region of upper epidermis of the median leaves and lower epidermis of the lateral leaves. The characters of the leaf macromorphology and of the micromorphology of the epidermal cells as well as the distribution patterns of stomata prove to be important for species delimitations in the Selaginellaceae. The studied species can be differentiated according to the following characters: (1) the shape of leaves (dimorphic vs. monomorphic); (2) the leaf arrangement (spiral vs. alternate); (3) the shape of the anticlinal walls (straight, arched, sinuate or sinuolate); (4) the shape of the cells of upper and lower epidermis (homomorphic vs. heteromorphic); (5) the type of the stomatal apparatus (anomocytic vs. actinoid); and (6) the difference in distribution of stomata on the upper and lower epidermis of the lateral and the median leaves.