Study On Cytologic Characteristic And Systematics Of Seriphidium (Compositae)

There is no consensus on the intergeneric relationships and systematic position of the genus Seriphidium (Bess.) Poljak. because Seriphidium is a genus distributed widely and superposed of morphology characteristics between species. Seriphidium have important value in medicinal, fodder and ecology, having immense potentialities in developing.The morphology characters, karyological data and cytogeography of species were studied. We discussed the delimitation and further explored the chromosomal characteristics of Seriphidium in China and evolution of Seriphidium based on the available chromosomal data and geographical distribution. Main results were as follows:1. There are 20 species and 1 variety of Seriphidium in Hebei university herbarium concluded by consulting literatures and specimens. 7 Ser. 18 species and 1 variety are contained in Sect. Seriphidium, Sect. Minchünensa and Sect. Juncea included 1 Ser. 1 species. The classification of between Sect. by way of the morphology characters of leaf and lobelet, meanwhile, synthesize the relevant characters of leaf, stem and capitulum can differentiate between Ser. of Sect. Seriphidium.2. The species multi-access key of Seriphidium was made on the basis of interspecific difference. Multi-access key operate easily, avioded to lookup come-and-go in dichotomous key and parallel key.3. The karyotype analysis of 12 species from Seriphidium were studied, and the results show all 12 species have the cardinal number 9, exception S. schrenkianum (2n=36), other 11 specie were 2n=18. Stand by regarding S. schrenkianum as the most advanced species in Seriphidium; proposal reverses the position of S. transiliense and S. nitrosum. The type of karyotype can be divided 1A, 2A, 2B and 2C. In the light of these available cytogenetic features, Seriphidium is clearly placed within the genus Artemisia L., so that it dose not make sense to segregate it as an independent genus.4. According to the longitude and latitude of 6 species in Seriphidium, we made the distribution maps by Arcview gis 3.2. Synthesizing the information of cytologic characteristic, the orientation of evolution of 6 species, from ancestral to advanced, is: S. kaschgaricum , S. sublessingianum, S. gracilescens, S. transiliense , S. nitrosum and S. schrenkianum.