作 者 ：李兆孟；周勇辉；刘玉萍；苏旭*
期 刊 ：植物研究 2016年 36卷 1期 页码：10-25
Keywords:Poaceae, Leymus, morphological character, morphological of leaf epidermis, biosystematic relationship,
摘 要 ：通过对先前学者报道的国产赖草属24个物种、72个代表居群形态和叶表皮微形态性状特征的观测和研究，结果发现：(1)原国产赖草属物种在旗叶长宽、叶片被毛状况、花序直曲和长宽、穗轴每节小穗数、每小穗小花数、外稃和内稃长度等15个外部形态学性状上均存在不同程度的差异，可将参试物种区分为3个不同的组；大赖草、粗穗赖草、硕花赖草和柴达木赖草多穗组植物的穗状花序粗壮呈圆锥状、直立、密集，穗轴同节着生3多枚小穗，每小穗常含3~10小花，颖线状披针形等，致使其处于该属最原始的地位；皮山赖草、若羌赖草和格尔木赖草单穗组物种的穗状花序细弱呈线状、直立、疏松，穗轴每节仅着生1枚小穗，每小穗往往含2~5小花，颖线状披针形或锥形，这些较高级的外部形态特征使得该组植物隶属于赖草属中较高级的类群；而少穗组植物的外部形态性状通常介于前两组植物的中间过渡状态，因而它的系统地位自然也应处于多穗组和单穗组植物之间。同时，依据外部形态性状的递变趋势分析显示，3组植物具有直接的派生渊源。(2)国产赖草属植物的叶表皮皆由长细胞、短细胞、气孔器细胞和刺毛所组成，表现为典型的狐茅型；它们除在长细胞类型和壁的厚薄、气孔器保卫细胞的体积和类型等性状上具有明显重叠而显示相似外，其它多数性状如长细胞的长度和壁的波曲程度、短细胞的分布式样、副卫细胞的形状及刺毛的类型等性状上具有明显差异，其可将赖草属植物鉴分为与形态学界定结果完全相同的3个组。同时，根据3组植物及组内物种叶表皮性状的演化趋势，对各组和组内物种的演化关系和系统位置分析表明，多穗组植物最原始，少穗组植物较进化，单穗组植物最高级；多穗组可能直接派生了较进化的少穗组，并在少穗组的基础上进而产生了最高级的单穗组。赖草属属下类群的这一系统关系与利用外部形态特征所获得的系统与进化关系基本一致。
Abstract:We analyzed the main character differences of seventy-two reprehensive populations from twenty four Leymus species previously reported by scholars by morphological observation and anatomical analysis of leaf epidermises. There are different degrees of difference in fifteen morphological characters including length and width of flag leaves, hairs of leaf blades, straight/curve and length/width of inflorescence, spikelet No. of each inflorescence, floret No. of each spikelet, length of lemma and palea. The tested species can be divided into three sections according to them. The sect. Racemosus species of L.racemosus, L.crassiusculus, L.pluriflorus and L.pseudoracemosus, with sturdy, erect and thick spike, 3-number of spikelets per rachis node, 3-10 florets each spikelet, linear lanceolate glume, etc., is the most primitive one in genus Leymus. Due to the sect. Anisopyrum species including L.pishanica, L.golmudensis and L.ruoqiangensis, having thin, erect and loose spike, only one spikelet per rachis node, usually 2-5 florets each spikelet, linear lanceolate or cone glume, etc., so it is the most advanced of them. Meanwhile, because the external morphological characters of the sect. Leymus species usually lie in the intermediate transition state between the first two groups, naturally its systematics position should also be between the sect. Racemosus and sect. Anisopyrum species. At the same time, based on the evolutionary trends of the external morphological characters of three above sections, we deduced that the sect. Racemosus might produce immediately the sect. Leymus, whereas the sect. Anisopyrum might derive immediately form the sect. Leymus. The leaf epidermis of Leymus from China consists of long cell, stomatal cell, short cell and prickle hair. It belongs to the typical festucoid type. Except that some characters, such as the type of long-cells and thick/thin of cell walls, the volume and type of guard cells from stomatal apparatus, have obvious overlap and show similar, other characters, including the length of long-cells and curve extent of cell walls, distribution pattern of short-cells, shape of subsidiary cells, and type of prickle-hairs, have obvious differences. They can delimitate Leymus species into three sections identical with the morphology. According to the evolutionary trends of leaf epidermal characteristics of three sections and species within each section, their evolutionary positions and relationships were inferred. The results show that the sect. Racemosus is the most primitive one among three sections, the sect. Leymus is slightly more advanced than the former, and the sect. Anisopyrum is the most advanced of them. The sect. Racemosus might produce immediately the sect. Leymus, whereas the sect. Anisopyrum might derive immediately form the sect. Leymus. The biosystematic relationships of taxa below the genus are corroborated by the evolutionary trend of external morphology.