雪莲的生物学特性研究 摘 要 本文通过野外观察与室内实验相结合的方法 对雪莲Saussurea involucrata Kar. et Kir. Sch. –Bip.的生境发育解剖学胚胎学繁育特性及幼苗生长特性进行了研 究并就其对特殊环境的适应性及其致危的原因进行了探讨主要结果如下 1雪莲是一种典型的多年生一次结实的高山植物在天山该植物一般生长在 高山带砾石质土壤及悬崖峭壁的石缝中其生境气候多变昼夜温差大风大氧气稀 薄紫外辐射强烈在营养生长阶段其植株具短缩茎叶基生密集呈莲座状进入 生殖生长的植株地上茎一般高达 1 5 - 4 0 c m 近顶端苞叶多枚将复头状花序包裹 2在根的初生结构中其初生木质部为二原型木质部及韧皮部的发育均为外 始式在初生结构向次生结构的发育过程中皮层细胞异常活跃近外皮层的细胞解体 形成根中发达的通气组织近内皮层的细胞恢复分裂能力旺盛分裂形成大量的薄壁细 胞而参与根的加粗生长中柱鞘细胞除参与侧根的形成外还参与维管形成层的形成根 的加粗生长是维管形成层和皮层细胞共同参与的结果 同时木栓形成层也起源于近表皮 的皮层细胞这在其他植物根中是少见的在多年生植株根茎过渡区出现的绳索状 异常结构则是由于其内部维管束裂分的结果此外雪莲的地上茎及成熟叶中维管束均 为双韧型且外生韧皮部与木质部间的形成层细胞分裂旺盛茎中空具较大的髓腔 根茎叶中均有发达的通气组织和分泌道分布 3 花药壁的发育为双子叶型绒毡层为腺质绒毡层小孢子母细胞减数分裂时 胞质分裂为同时型小孢子四分体多为四面体型成熟花粉为 3 - 细胞雌蕊子房下位 2 心皮合生成 1 室胚珠 1 枚基生胎座倒生胚珠单株被薄珠心大孢子四分体 为直线形合点端大孢子为功能大孢子胚囊发育类型为蓼型胚胎发育为紫菀型胚 乳发育为核型具无融合生殖现象反足细胞胚 4 花序及花的开放式样独特开花期苞叶内温度较苞叶外明显高出许多可为 苞叶内复头状花序的生长发育传粉受精提供适宜的微环境同时其花开放时存在着雌 雄蕊异速生长现象雄蕊先于雌蕊伸长生长花药内向开裂为雌蕊在随后生长过程中 柱头的有效受粉创造了极为有利的条件此现象在其他菊科植物中少见报道此外该 种植物传粉昆虫少访花频率极低但可育花序平均结实率为 5 6 . 7 2 2 4因此我 们认为该种以自花传粉为主而雌雄蕊异速生长可能是促进其自花传粉的一种机制 5 该种存在两种颜色的瘦果且其在大小质量和萌发特性上均存在差异 6 雪莲单株结实量平均可达 6 6 8 粒在适宜条件下其瘦果萌发率在 8 0 % 以上 即使在恶劣的自然生境中瘦果萌发率很低延缓了种群的扩展但并不会影响到种群 繁衍因此其内在繁育特性并不是导致该种濒危的直接原因而人们对其花期植株的 疯狂采挖致使其瘦果无法形成土壤中雪莲种子库无法得到补充才是导致该种资源 储量急剧减少物种濒危的根本原因 7 在室内外不同条件下瘦果萌发率萌发时间幼苗生长状况均表现明显 的不同 关键词雪莲 发育解剖学 胚胎学 繁育特性 幼苗生长特性 The Biological Characters of Snow lotus (Saussurea involucrata) Huang Jihong (Botany) Supervised by Tan Dunyan Abstract The biological characters of Snow lotus (S. involucrata Kar. et Kir. Sch. –Bip.) including the traits of habitats, vegetative developmental anatomy, embryologyreproductive characteritics and the growth traits of seedlings were studied by both the field observation and the experiment indoor in this paper. Meanwhile, the reasons which endanger this species were discussed. The main results were as follows: 1. Snow lotus is a typical perennial, monocarpic, alpine plant. In Tianshan mountain, it usually lives in the extremely rigorous environment generally, in which there is lack of the soil. The climate of the habitats is variable companied with big wind, scarce oxygeon and strong ultraviolet, and the discrepancy of temperature between the day and night is high. The vertical stem is short with the dense rosette leaves during the vegetative growth and elongates quickly to 15-40cm during the reproductive growth. There are many capitulums at the top of stem, with many bracts around these capitulums. 2. In the primary structure of root, the primary xylem is diarch and the development of both the primary xylem and the primary phloem is exarch. During the developmental process from the primary structure to the secondary structure of root, the cells of cortex is active: the cortex cells close to the exodermis disintergrate and result in the formation of aerenchyma, and those next to the endodermis differentiates actively to produce a large number of the thin wall cells to contribute the secondary structure in root. The lateral root as well as the part of the vascular cambium develops from the pericycle. So the secondary growth of root results from the activity of both vascular cambium and parenchyma in the cortex. Meanwhile, the phellogen comes into being in the cortex under the epidermis. This mechanism is rare in other plants. The root-stem transition region and the root in the elder plant reproduce the abnormal secondary structure which is similar to the rode caused by separation of the vascular bundle. Moreover, the vascular bundles in stem and leaf are amphicribral and the cambium between the exogenous phloem and the xylem acts strongly. The stem is hollow with pith cavity. There is a great quantity of aerenchyma and secretory canals distributed in root, stem and leaf. 3. The development of the anther wall follows the Dicotyledon type. Tapetum is the secretory type. The cytokinesis of the microspore mother cell is of the simultaneous type. The microspore tetrads are tetrahedral mostly. The mature pollen grain is the three-celled type. The ovary is bicarpellary and single locule. Each locule contains a single ovule. The placenta is situated at the base of ovary. The mature ovules are amphitropous, unitegmic, tenuinucellate. The megaspore tetrads are linear. Usually, the chalazal megaspore is functional. The development of the embryo sac is of the Polygonum type. The embryogeny conforms to the Astered type.The development of the endosperm complys with the Nuclear type. Antipodal embryo is existent in the Snow lotus. 4. The display pattern of the floral is particular. The average of day temperature inside the bracts is obviously higher than that outside the bracts. The higher temperature inside the bracts provides the development, pollination and fertilization of the capitulums with the optimal micro-environment. Furthermore, the pistil and the stamen grow at different speed at the flowering. The rapid elongation of the steman is prior to that of the pistle and the anther is congitudinal dehiscence inward. This special growth pattern of the pistil and the stamen makes the。