| Astereae, which belongs to Asteraceae, has 222 genera and about 3100 species. There are 14 subtribes(conclude Asterinae) form the Astereae. Aster is the biggest genera in Astereae.In Europe and Asia, Aster s. lat. concludes not only most of Asterinae,but also some groups which are similar but not paternity to Aster s. lat. So classifying Aster is the key and the difficult point for classifying Asterinae.Arctogeron DC. belongs to the groups which have close kin to Aster, but all the time,people has little research on the Arctogeron DC systematics and has close relations with neighbouring spices, all the reasons cause its classification boundary uncertain. So having a research on this species has great meaning on discussing the classification and the relationship in the genera.This paper selects out 9 representative genera in Astereae—Heteropappus Less.,Doellingeria Nees,Aster L.,Krylovia Schischk.,Asterothamnus Novopokr.,Galatella Cass.,Crinitaria Cass.,Tripolium Nees Erigeron acer. Through observing the stable and valuable characters(such as Floral organ micromorphology; leaf epidermis; karyotype analysis) under the microscope and anatomical microscope,we determine the relationship between Arctogeron and other related plant. The experimental results provide new valuable evidence for the family of the Astereae systematics. The main research results are as follows:1.According to the micromorphological observation in Arctogeron and other 9 related plant.including a large number of characters analysis—tubiformfloret style,anther,achene,pappus and corolla,and referring to 1994 the latest assessment of generalized Asterinae from Nesom as well as the preliminarily compares on morphology in representative genus of species of Astereae and Flora of China(Tomus 74), all the evidences are in support of Arctogeron belongs to Astereae.2.Having a research from the leaf epidermis micromorphology of Arctogeron and other 9 related plant:Observing Arctogeron and other 9 related plants on the leaf epidermis with light microscopy. Research shows that the stoma are widely spread in the leaf of upper and lower epidermis, the stoma types are mainly for anisocytic and anomocytic. Arctogeron epidermmal cells of leaf are polygon, the type of anticlinal wall is arced to straight. It has certain differences between the stoma and epidermal cells form. So we can speculate that leaf epidermis micromorphology can be used for resolving the division in family of some species of Astereae.3.Through having a karyotype analysis on chromosome number, chromosome form and so on, we firstly report the characters of the chromosome of Arctogeron:the chromosome number is 18,the base number is 9,the average length is 2.71μm, the karyotype formula is 2n=2x=18= 16m+2sm, the range of volume is 2.16μm3-3.27μm3,the total volume of chromosomes is 25.24μm3,the category of Karyotype is 2A,which has a increased similarity. These are quite in conformity with forefathers' research,which support the view that Arctogeron belongs to Astereae.4.Through observing in field instgation and searching the protologue specimens,we found that there is no suitable habitat for this genera in Hebei area,so we can infer that it is wrong that Arctogeron distribute in Changping aere in Beijing which are recorded in Flora of Beijing and Flora of Hebei, and draw the geographical distribution map of Arctogeron. |
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