Buttercup Family (ranunculaceae) Study

The features of floral morphogenesis,the perforation plate of vessels,the leaf epiderm of Ranunculeae were described in the present paper with the aim to elucidate the systematic position of the tribe and the phylogenetic relationship among the genera.The main results are summarized as follows:1.Floral MorphogenesisThe floral morphogenesis of 5 species:Batrachium,Ceratocephalus,Halerpestes and Ranunculus from the tribe Ranunculeae of Ranunculaceae was observed with a scanning electron microscope(SEM) and by means of histological methods in order to expand our knowledge of the morphogenesis and development of floral organs of the Ranunculaceae.The results show that the initiation and early development of floral organs in the genera of Ranunculeae are in high resemblance.All floral organs are initiated centripetally with the initiation sequence following the Fibonacci number and are spiral.The sepal primordia are different from other floral organs in shape.The petal primordia are retarded except in Oxygraphis.The stamen primordia form several parastichies,while all stamens are arranged in one whorl during the developmental process of Ceratocephalus.The stamen primordia mature rapidly during the initiation of carpel primordia. The number of carpel primordia increased along with the heightening of the floral apex.The increasing volume of receptacle provides necessary space for more carpels.So we speculate that the large number of carpels in Ranunculeae may be derived.The carpels are ascidiate,and the ovules had formed before the ventral suture enclosing.The styles are not evident.The stigma which consistes of unicellular papilla formes by the outspreading of the conduplicated part at the top of carpel and is decurrent along the ventral suture,and slightly everted.The flowers aggregate into a simple cyme in Halerpestes,Batrachium and Ceratocephalus which also present in Ranunculus.We consider that the simple cyme might be the continuous transition from cyme to a scape in Ranunculus(s.l.).The petals are all flat limbs at the early development stage and nectary integuments are formed on the adaxial wall during the later developmental process.So the various types of nectaries are derived characters.We support the idea that Halerpestes,Batrachium and Ceratocephalus should be included in Ranunculus based on the floral morphogenesis and morphological data.The flower is solitary,and the petals are numerous and not retard in Oxygraphis which may characterize Oxygraphis as a special group in Ranunculeae.And it should not be included in Ranunculus(s.l.).2.Vessel Elements In Ranunculeae,most of the end wall perforation plates of the vessels are simple-perforation plates or scalariform perforation plates.The types of the vessel in Adonis are diverse.While in Batrachium,the vessel elements are degradated which are adapt to the aquatic environment.3.Structural Characters of Leaf EpidermisThe leaf epidermis of 10 species,representing 7 genera of the tribe Ranunculeae was examined by scanning electron microscopy(SEM).It is shown that the stomata are often anomocytic.The leaf epidermal cells are usually regularly or irregularly polygonal in shape.The patterns of anticlinal walls are sinuolate or sinuate.The inner margin of the outer stomatal rim is nearly smooth or sinuolate,and the cuticular membrane of the leaf epidermis is often striated.In Batrachium,the leaf epidermis is degenerated.4.Cladistic Analysis and Systematies Relationship7 genera in Ranunculeae and are cladistically analyzed based on character of floral morphogenesis,vessel elements and structural characters of leaf epidermis and the former date, using Anemone as out group.The Ranunculeae is a monophyletic group,and Callianthemum and Adonis form an independent clade as the sister group of this tribe.We consider that Halerpestes, Batrachium and Ceratocephalus should be included in Ranunculus(s.l.).The Ranunculeae should only include Ranunculus(s.l.) and Oxygraphis in China.And Adonidinae should be upgraded to Adonideae which include Callianthemum and Adonis.