【作者】 常鸿莉；

【导师】 任毅；

【作者基本信息】 西北大学 ， 植物学， 2005， 博士

【摘要】 花,作为被子植物独有的繁殖器官,被认为是被子植物植物体形态上最复杂的一部分。与其它植物类群中的同等结构相比,被子植物的花更为多样。花器官最为精确的反映了其所属分类群的系统学意义和分类学地位,其形态学特征被认为是对被子植物演化进行系统性构建的传统依据。因此,花器官的起源和演化成为探讨被子植物起源的关键问题。目前,被子植物花器官演化问题的着手点之一对现存的基部被子植物的研究,如ANITA群和毛茛类植物等。 毛茛科(Ranunculaceae)是被子植物中一个相对大且分布广泛的分类群,有59个属,几乎分布于全世界。同时,它又是被子植物和真双子叶植物的基部类群之一,也是最接近自然的一个分类群。它具有位于双子叶植物系统发育最低类群中的许多原始特征。毛茛科植物也是毛茛目植物中变异最为丰富的一个科,主要表现在该科的花模式多样性和花结构的变异性。前人已经从毛茛科部分植物花的形态学、解剖学、分子遗传学等方面进行了报道。但对毛茛科植物花的研究(如结构、形态和花器官之间的相互关系)大多集中在对成熟花的比较研究上。目前已经知道,成熟花只是花发育过程中一个阶段的反映,它不能全面准确反映花发育过程的全部信息。所以,毛茛科花发育中的许多细节并未被人知,因此为对毛茛科植物花系统发育有全面的了解,迫切需要人们利用动态的眼光,着眼于花器官发生和发育的全过程,以增进对毛茛科植物花模式和花结构形成成因的认识。 花的变态现象在毛茛科银莲花属、蜀侧金盏花属和鸦趾花属中发现。在银莲花属的变种植物小花草玉梅中,花部器官有不同程度的变态现象,其花被片、雄蕊及雌蕊均可以变为绿色叶状物,变态花器官最强烈变态是具长柄、三或五深裂,两面均有气孔器和毛被。花器官在向叶状器官变态的过程中,在颜色、形状、脉序、毛被和气孔器等方面存在着连续的变态梯度。 本研究中采用广义的毛茛科(Ranunculaceae s.l.)概念,对国产毛茛科植物不同亚科、族或亚族的代表属的植物进行花形态发生、发育研究,同时对毛茛科尤其银莲花属的小花草玉梅花变态现象做了研究,并分析了小花草玉梅变态花中变态花各花部的形态和显微学的变化特征和意义。取得了以下结果: 1.毛茛科许多植物的花部按照2/5序列螺旋状向心式发生;但在耧斗菜属、唐松草属、铁线莲属和独叶草属中,花部器官在发生时,花原基尤其花被片原基之间的间隔期长短不一致,成熟时花部器官轮状排列。由此认为,毛茛科植物花的花部螺列是原始性状,它向更高级的轮列演化。 2.毛茛科植物不同属植物的花在形态发生过程中,均表现出了不对称性。 3.毛茛科许多植物的花萼片的原基形态和其它花器官都不一样,结合该科植物小花草玉梅变态花的研究,认为毛茛科植物的花萼片可能来源于苞片。更多还原

【Abstract】 Flower, as the special reproductive organ of the Angiosperms, are believed to be morphologically the most complicated parts of Angiosperms. The floral diversity patterns of the angiosperms are more complex than the reproductive organs in other plant groups. The characteristics of the floral organs reflecting the systematic significance and taxonomic position of the group most exactly and correctly. The question of the floral origin and evolution become a leading question to investigate the origin of the angiosperm. At present one of the key respects to study the floral evolution of the angiosperm is to study the living basal angiosperm, such as ANITA and Ranalean.Ranunculaceae is a most natural and a world wide distributed family with 59 genera. It is considered as not only the most primitive family of the living herbaceous angiosperms, but also one of the basic groups of eudicots. Ranunculaceae is the most diversity family among the Ranunculales, which main reflects on the variety of flower patterns and structures. There have been a lot of reports on the morphology, anatomy, and molecular systematics on Ranunculaceae. With regarding to the flowers of the family, such as the floral structure, morphology and the relationships between the floral organs, have been focused mostly on the mature flowers. A mature flower is one of the developmental stages, it contains only the information of the mature stage, but can not embody all the developmental information of the flower. Therefore, many details of the floral initiation and development in the family are still unknown to us. To expand the phylogeny knowledge of the flowers of Ranunculaceae and enrich the floral pattern and structures, a dynamic viewpoint is needed to consider the process of the floral initiation and development.The metamorphosed flowers in Ranunculaceae have been found in Anemone Linn., Adonis Linn, and Oxygraphis Bge. In the metamorphosed flowers of Anemone rivularis Buch.-Ham. ex DC. var. flore-minore Maxim., all of the metamorphosed floral organs can change into leaf-like organs and showing a different metamorphosed degrees. The most metamorphosed floral organ has long stipe, three or five lobed, and with dense stomata and hairs on both surfaces. A continuous gradient in aspects of the number, the size, the color, the shape, the margin, the stomata and the hairs as well asthe venation between the normal and the metamorphosed organs could be found.In this study the floral morphogenesis and metamorphosis of the representative genera from different subfamilies, tribes, and subtribes in Ranunculaceae (s. 1.) in China were observed. The results showed that:1. All of the floral organs initiate in a spiral, 2/5 sequence, and spirally arranged at anthesis; but the plastochron between the perianth is different in Aquilegia Linn., Thalictrum Linn., Clematis Linn., and Kingdonia Balf. f. et W. W. Smith. And the arrangement is whorl at anthesis. We conclude that the spirally arranged floral organs is primitive, the whorl arranged are derived in Ranunculaceae.2. The flowers of different genera of Ranunculaceae are unsymmetrical in morphogenesis.3. The sepal primordia of Ranunculaceae are different from other floral organs. Considered with the metamorphosed sepals in flowers of Anemone rivularis var. flore-minore we deem that the sepal origins from bract in the family.4. The petals are special named as honigblatt in Ranunculaceae. In the species of Ranunculaceae the petals are with or without nectary. Petals are morphological changeable. In Paeonia Linn., petals are resemble with that of the bracts and sepals, but different with the stamens in shape and position in morphogenesis. But in other genera the shape of the petal primordia is resemble to that of the stamens. The petal is retard in their early development stages compared with stamen. Thus we think the petal is either evolved from bract (Paeonia) or from stamen (excluding Paeoni) in Ranunculaceae.5. The initiation of the stamen is centripetal (excluding Paeonia). But the development sequence and the occurrence of the microspore are diversity: there are centripetal, centrifugal and from the center to the tip and the base in a longitudinal section of the flowers.6. The carpels possess different morphology during the carpel development. It can be divided into four types according to the closing of the carpels: 1) The carpel primordia forms a longitudinal depresses at the base and the depresses runs through the carpel in later developmental stages. The carpel resembles a conduplicated leaf before the carpel closes up. The closure of the carpel is synchronizate. 2) The carpel primordia forms a rounded depresses at the base and the depresses runs through the carpel in later developmental stages. The closure of the carpel is not synchronizate. 3) The carpel primordia forms a longitudinal depresses at the base, and then the base of the carpel curved and connected at the base. 4) The carpel differentiates into a basal stalk and an upper blade. The stalk will develop into a short ovary stalk in the later developmental stages. The blade becomes slightly concave at the base and conduplicated later. The concave disappear at the top of the carpel.7. The flower pattern diversity of Ranunculaceae is not only on the mature structures but also on the initiation and development of the floral organs. During the ontogeny process the same floral organ also have different characteristics.8. From an ontogeny point of view, we considered that: 1) Paeonia should exclude from Ranunculaceae. 2) Aconitum Linn, and Delphinium Linn, have high similarity in floral morphogenesis. 3) The floral morphogenesis of Aquilegia Linn, issimilar to the genera of Trib. Delphineae. 4) The floral morphogenesis of Thalictrum Linn, of Subfam. Thalictroideae is not similar to the Aquilegia of the same subfamily but similar to that of the genera of Subfam. Ranunculoideae. 5) The floral morphogenesis of Anemone Linn, of Subtrib. Anemoninae, Trib. Anemoneae, Subfam. Ranunculoideae is similar to that of Pulsatilla Adans. in the same subtribe. 6) The genera, Callianthemum C. A. Mey. and Adonis of Subtrib. Adodininae of Trib. Ranunculeae, show the high resemblance in floral morphogenesis and they relative with Oxygraphis Bge.9. The phenomenon of Anemone rivularis var. flore-minore that the floral organ expressed characteristics of leaf-like organ was considered to be an atavism. The characteristics, such as greenish, the anastomosous venation, the stomata and hairs on both surfaces, and the trilobes that with lobelet or serrature, show the leaf-like tendency of the metamorphosis. Therefore we concluded that the ancestor of the floral organ is leaf like organ, or at least during the early evolution of the floral organ the leaf like organ once occurred. Considered the metamorphosed flowers of Adonis and Oxygraphis we conclude that the flower organs had the same origin and are homeosis with each other and evolved from leaf-like organ.更多还原