类短命植物新疆猪牙花解剖结构及其生态适应性的研究

Anatomy and its ecological adaptation of an ephemeroid Erythronium sibiricum in Xinjiang

关键词:  新疆猪牙花  解剖  类短命植物  适应  拟栅栏组织

Key words:  Erythronium sibiricum  anatomy  ephemeroid plant  adaptation  semi palisade tissue

摘要:

新疆猪牙花是分布于新疆阿勒泰地区西伯利亚落叶松林下的一种多年生高山类短命植物。解剖学研究结果表明：其地下鳞叶中薄壁组织发达，是重要的储藏器官，为该植物每年长达10个月的休眠提供了充足的水分和营养物质的储存空间。茎由表皮、基本组织以及3～4轮散生的维管束组成；茎表皮细胞具厚角质层，能有效降低体内水分的散失；发达的维管束为其在冰冷的土壤中有效地吸收水分和养分，实现碳水化合物由地下器官向地上器官的转移和物质重新分配提供了有力保障。发达韧皮纤维为支撑顶部的花、果器官提供了必要的机械支持。叶片大而薄，有助于增大光合器官的面积；叶表皮角质层不明显，可以减少对日光的反射；叶肉有海绵组织与“拟栅栏组织”的分化，后者的细胞呈长柱形，其长轴方向与叶表皮方向平行，多层排列，能有效提高叶绿体对光能的捕获效率，是该植物对林下弱光生境长期适应的结果。花被片中维管束密集，发达的维管组织对维持花被片薄壁细胞的膨压，维持花被片较长时间的强烈反折状态以增加被昆虫访花的机会，提高昆虫传粉效率，促进繁殖成功具有关键作用；中轴胎座，胚珠多数；柱头与花柱中空，内表面具分泌细胞，有利于花粉管的快速萌发和迅速伸长。

Abstract:

Erythronium sibiricum is an ephemeroid in Xinjiang Altai，distributing in alpine grassland under Larix sibirica Ledeb. forest with shadow habitat. In the present paper，anatomy and its ecological adaptation of E.sibiricum was studied. The results showed that there was significant parenchyma in subterranean scale leaf，which provided sufficient location of water and nutriment for E.sibiricum during its above 10 month dormancy every year；stem (scape) of E.sibiricum consisted of epidermis，ground tissue and sparsate closed vascular bundles. There was a thick layer of cuticle on the epidermis of stem，which could save inside water from evaporation，lots of vasculars were able to ensure water absorption from cold soil and nutrients allocation to shoot efficiently. There was significant phloem fiber in every bundle that played a very important role in bearing large flower or fruit on the top of the stem；leaf was large and thin with little cuticle on the epidermis，which could not only lessen sunlight reflection，but also enlarged photosynthetic surface. Besides spongy tissue，there was another kind of special mesophyll tissue “semi palisade tissue” in asssimilating tissue constituted with layers of elongate cells，whose macro axis was paralle with the leaf epidermis，and it means a significantly enlarged photosynthetic tissue area，suggesting an adaptation to the shadow habitat of E.sibiricum under the forest where the sunlight was not sufficient；there were densy veins inside of the parianth，which acted as a keystone role in sustaining enough water supply，sustaining cell normal turgor pressure，sustaining optimal spatial showing pattern of parianth，and in improving pollination efficiency，ensuring reproductive success. It was also the result of the long period adaptation of the plant to its shadow forest habitat，where the pollinators were not reliable；axile placentation with much ovules in each locule，and style was hollow，and style canal was obvious and with secretory cells on its inner epidermis，which was helpful to rapid germination of pollen and enlongation of pollen tube.