Morphogenesis Of Zygomorphic Flower And Its Petals In Delphinium Anthriscifolium (Ranunculaceae)

Zygomorphic flowers are considered to be more evolutionary in angiosperms,and thus have been interested by many investigators from various subjects.In this study,using scanning electron microscopy,floral organogenesis of Delphinium anthriscifolium(Ranunculaceae)is comprehensively investigated,and micro-morphological features of different petals have been traced.Pivotal results are follows:1)After the specimen information of Delphinium anthriscifolium were examined from the database at home and abroad,and the distribution of the natural populations in the wild were investigated during botanical expedition,the distribution patterns of its three varieties are revised: D.anthriscifolium is widely distributed in the most areas south of Qinling Mountains and Huaihe River,of which var.savatieri is distributed along the Yangtze River and the Huaihe River,and var.majus is distributed in Hubei Province and its borders with Hunan,Chongqing and Shanxi.2)Based on population's investigation,morphology of three varieties,especially the flower and petal,have been compared,and some key characters and illustrations have been suppled.3)Floral development of Delphinium anthriscifolium is divided into 20 stages defined by a series of landmark events.And floral symmetry is not stable,until the zygomorphic flower was established at stage 10 when the spur of sepal was emerged.4)The differentiation of various petals occurred after the petal primordia developed into the ellipsoid-shaped.At the moment,four ventral petals gradually ceased and two dorsal petals grow rapidly.The development of the dorsal petal and the lateral petal can be divided into 14 and 12 stages respectively.5)All types of epidermal cells in the mature Delphinium anthriscifolium petal(11types of spurred petal and 7 types of flat petal)were all derived from the polygonal cells in the petal primordium.The difference of epidermal cells between the spurred petal and the flat petal may be due to the functional divergence during petal evolution.In short,organogenesis of zygomorphic flower in Delphinium anthriscifolium and its petals have been illuminated,and the dynamic changes of floral symmetry and the epidermal differentiation between the spurred petal and the flat petal have been suggested.These results lay a solid foundation for better understanding of the process and mechanism of petal development and evolution within Delphinium and Ranunculaceae.