旱生植物

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 cell-walls, the absence of filaments on the leaf surface, and the fewer layer cells in the costae, the absence of hydrome and steroid cells. These features make it adaptable to aquatic environments. For Pogonatum inflexum and Atrichum undulatum, 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 thy conditions.

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Plagiomnium rostratum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Hygrohypnum 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 inflerum和波叶仙鹤藓Atrichum undulatum的叶腹面覆盖着栉片，东亚砂藓Racomitrium japonicum、大羽藓Thuidium cymbifolium、福氏蓑藓Macromitrium ferriei、东亚短颈藓Diphyscium fuhifolium、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。

With the deflected succession of aquatic ecotype plant functional group,the dominance of mesophytes and xerophytes increased,while the dominance of aquatic and hygric plants decreased. However,there are only planting crops in the reclaimed wetland. In the composition of plant biotype functional group,the hydrophytes reduced quickly with the deflected succession and the dominance of perennial herbs is mostly marked,and there are only annual herbs in reclaimed wetland. Compared with primary swamp,the species diversity index of meadow is the highest,the swampy meadow follows,and the reclaimed wetland is the lowest.

植物的水分生态型功能群组成随湿地的逆行演替，水生、湿生类植物功能群的优势度不断减少，中生、旱生类植物功能群的优势度逐步增加，而在垦后湿地只有农作物；植物生活型功能群组成随湿地的逆行演替，水生草本迅速减少，陆生多年生草本增加占据优势，而在垦后湿地均为一年生草本；湿地植物物种丰富度、多样性指数由原生沼泽、沼泽化草甸到草甸依次增加，草甸为最大值，而垦后湿地则最低。

Flooding,as a kind of disturbance events,occurred with higher and higherfrequency over the world.To investigate the effects of flooding disturbance ongrassland vegetation and the soil,a comparatively thorough study was conducted onAneurolepidium chinense grassland in Songnen plain,Northeast China.The studysite was located in Sanjiadian National Rangeland in the territory of Da'an city,Jilirprovince,which was partly flooded in 1998.On the study site,Several transectssubjected to different flooding durations and intensities were designed for thecomparative study among them on such aspects as vegetation characteristics,seedbanks,vegetative propagation of rhizomatous plants,distribution patterns ofpopulations,interspecific relations,and physio-chemical properties of soil.Theresults were as follows:(1)Of the functional group composition of the vegetation,with the elongation of the flooding duration or the increase of flooding severity,theratio of hygric and hygro-mesic plants increase,while that of mesic and mesoxericplants decrease,of Therophytes changed unimodally,of Geophytes increased,whileof Hemicryptophytes decreased.

为弄清草地植被及其土壤环境对水淹干扰的响应，在松嫩平原羊草草地1998年部分遭受水淹的吉林省大安市三家甸子草场内设置了经历不同水淹干扰持续时间和不同水淹强度的样带，并在这些样带之间从植被特征、种子库特征、根茎植物的营养繁殖性能、种群分布格局、种间关系及土壤的理化性质等多个方面展开对比研究，主要结果如下：(1)在植被的功能群组成中，随干扰强度的增加和水淹干扰持续时间的延长，湿生、湿中生类植物功能群的优势度比例基本上是逐渐增加的，中生、中旱生类植物功能群的优势度比例则逐渐减小，而一年生植物的优势度比例呈单峰型变化，地下芽植物比例增加，地面芽植物比例减小。

Among three water ecological types, mesophytes occupied 59.37% of the total, and mesoxerophytes and xerophytes occupied 25% and 15.63%, respectively.

在3个水分生态类型中，中生植物最多，占59.37%，中旱生类型和旱生类型分别占25%和15.63%。

The dominant and co-dominant species in shrub and herb layers were mostly helophytes and hygrophytes. With decreasing latitude, the helophytes and hygrophytes decreased or disappeared, while mesophytes increased.

研究区沟谷冻土湿地植物群落的灌木层和草本层的优势种和共优种多为适应湿地环境的沼生和湿生植物，随着纬度的减小，喜冷湿环境的沼生和湿生植物种类逐渐减少，甚至消失，而耐旱的中生植物的比重则逐渐加大。

The physio-ecological characteristics of photosynthesis of the two extreme xerophytes were studied under natural environment.

在自然条件下研究了两种超旱生植物的光合生理生态日变化特征。

In some xerophytes, such as cacti, most of the leaves are modified into spines, greatly reducing the leaf area for transpiration; the photosynthetic function of the leaves is taken over by the green stems.

在一些旱生植物中，如仙人掌，大部分的叶片都特化为刺，极大的减少了叶片区域的蒸发作用，同时光合作用为绿色的茎所承担。

Xerophytes ; leaf structure ; ecological adaptation ; diversity

旱生植物；叶结构；生态适应；多样性

Anatomical observations of assimilating branches of nine xerophytes in Gansu.

标题 我国甘肃九种旱生植物同化枝的解剖观察。

Anatomical observations of assimilating branches of nine xerophytes in Gansu.

Title 我国甘肃九种旱生植物同化枝的解剖观察。

Chrysanthemum of 10 thousand birthday is lax to edaphic requirement, with the arenaceous qualitative loam with fecund, good drainage had better.

万寿菊对土壤要求不严，以肥沃。排水良好的砂质壤土为好。

He unstepped the mast and furled the sail and tied it.

他拔下桅杆，把帆卷起，系住。