System Taxonomical Based On Leaf Epidermal Micro-morphology Characteristics Of Atraphaxis From China

The genus Atraphaxis belongs to Atraphaxideae (Polygonoideae, Polygonaceae). About25species distribute in the world, mainly distributed in Central Asia and West Asia, Central Asia isconsidered as the geographical distribution centre of the genus Atraphaxis. Previous work tosystems of Atraphaxis is mainly based on morphological evidence, besides, previous views aboutthe systematics relationships are not consistent. In recent years, a study on micro-morphologicalcharacteristics of leaf epidermis was get more and more plant taxonomists attention. On the onehand, the nutrition organs of micro-morphological characteristics mainly reflection the hereditaryfeature of the species itself, the shape of the leaf epidermis, such as the type of epidermal cells,stomatal type and cuticular membrane characteristics to investigate extant of plant classificationsystem has important significance; On the other hand, by using micro-morphologicalcharacteristics of nutrition organs is more favorable to identification for various phenophase ofspecimens. The leaf epidermal micro-morphological characteristics of plant externalmorphological characters existing correlation, at interspecies and higher grade have the largeclassification of value. About leaf epidermal micromorphology work related to Atraphaxis at homeand abroad until now have not reported. Therefore, investigate system taxonomical by leafepidermal micro-morphological characteristics of Atraphaxis have important significance.This study collected eleven species of Atraphaxis and two related genera, another elevenspecies of Atraphaxis morphological characteristics data from foreign reference and Flora ofURSS, definite the morphological characteristics of Atraphaxis in China. eleven species in thegenus Atraphaxis from China was observed under SEM and investigate the leaf epidermalmicro-morphology character. Finally, combing with twenty three morphological character data, byusing cladistic and phenetic analysis of the infrageneric relationships of Atraphaxis based on themorphological characrers. The main results are as summarized as follows:(1) The morphological characteristics of Atraphaxis in ChinaThe genus Atraphaxis in China are eleven species and two varieties (Atraphaxis frutescens L.var. papillosa Y. L. Liu. and Atraphaxis bracteata. var. angustifolia Los.). three endemic species:Atraphaxis jrtyschensis Yang et Han, Atraphaxis manshurica Kitag. and Atraphaxis bracteata A.Los.. Northern of Xinjiang is also differentiation center of Atraphaxis in China. Atraphaxisreplicata Lam. and Atraphaxis decipiens Jaub. et Spach in Flora of Xinjiang need to be donefuture research.(2) Leaf epidermal micro-morphological characteristics of Atraphaxis in ChinaLeaf epidermal micro-morphological characteristics of eleven species of Atraphaxis(Polygonaceae) in China were observed and compared by scanning electron microscope (SEM),and its taxonomical significance was discussed. Hereby, key to eleven species tested was alsocompiled. The observation results show that micro-morphological characteristics (including shape of epidermal cells, pattern of anticlinal wall, surface ornamentation of leaf epidermis, cuticularmembrane, type of stomatal apparatus, inner margin shape of outer stomatal ledge andornamentation) on leaf epidermis of eleven species tested appear a highly diversity. Shape ofepidermal cell contains two type of irregular and polygonal, pattern of anticlinal wall contains twotypes of arched and straight, most species tested possess irregular epidermal cell and archedanticlinal wall. Surface ornamentation of leaf epidermis can be divided into four types of papillae,thin area, striate and thickened area, upper and lower epidermis of most species tested have nopapillae. Stomatal apparatus can be divided into three types of anomocytic, anisocytic andparacytic with a majority of anisocytic type. Cuticular membrane contains two types of striate andapophysis, in which some species possess granulas and striate is majority. Inner margin of outerstomatal ledge can be divided into two types of sinuolate and nearly smooth, ornamentation ofouter stomatal ledge also contains three types of granules, nearly smooth and striate. And sinuolateinner margin of outer stomatal ledge and granules ornamentation of outer stomatal ledge aremainly among eleven species tested. The analysis results indicate that diversity ofmirco-morphological characteristics of leaf epidermis among different species of Atraphaxis isrelatively rich, as a result, these characteristics are taken as references for distinguishing somespecies of the genus.(3) A cladistic and Phenetic analysis of infrageneric relationships of Atraphaxis based on themorphological charactersBased on23morphological characters,21species representing two Sect from Atraphaxis,and two outgroups, Oxyria digyna and Rumex acetosa were sampled to investigate theinfrageneric relationships by means of the cladistic and phenetic analysis. The results indicate thatAtraphaxis was a monophyly, and outgroups were entirely separate in Atraphaxis. Two sect inAtraphaxis could also formed monophyly respectively. The topologies of the trees obtained werelargely in congruence.