Morphological Variation And Habitat Heterogeneity Of Opisthopappus Shih

Opisthoppus taihangensis and Opisopappus longilobus of the Opisopappus genus are endemic and endangered species that only grow in Taihang Mountains.Although the morphological differentiations between these two species presents mainly on the leaves and bracts,they are still identified as one species according to the Flora of China.In this paper,we would explore the morphology characteristics and ecology niches of O.taihangensis and O.longilobus,which expecting to provide clues for the taxonomic status,sustainable utilization and scientific protection for these two species.The results showed that O.taihangensis and O.longilobus presented the rich flower morphological variations in different species/populations.Clustering analysis based on flower morphological characteristics could not completely separate the two species into two different branches,in which the populations of two species mixed together.Within leaf morphological characteristics,there were significant differences between O.taihangensis and O.longilobus and the all studied populations could be grouped into two branches.When considering leaf and flower morphological characteristics together,the first two principal components could well distinguish the two species,indicating that petal length,involucre diameter,sepal length,leaf area,leaf length,leaf petious width and leaf crack number could be regarded as the systematic indicators for O.taihangensis and O.longilobus.The phenotypic differentiations of these two species had an significant correlation with ecological environment factors,in which flower morphological characteristics was mainly affected by soil factors and leaf morphological characteristics was mainly affected by climatic factors.Among all 37 environmental variables,14 variables（bio 2,bio 3,bio 4,bio 8,bio 11,bio13,bio 15,elev,T＿Ca CO₃,TGRAVEL,T＿OC,T＿SAND,T＿SILT,T＿TEB）significantly influenced on the distribution of two species of Opisthoppus.The Schoener’s D and Hellinger’s I values based on the main ecological factors were 0.2870 and 0.5468,respectively,and the niche simulation histogram almost did not overlap,that indicating that O.taihangensis and O.longilobus occupied different niches.The distribution areas of O.taihangensis was mainly in the south,while O.longilobus in the north of Taihang Mountains,which might be affected by the different environmental factors and habitat conditions.In a word,the environmental heterogeneity of different species or populations would lead to morphological differentiations and niche divergences between O.taihangensis and O.longilobus,and further promote the variation of these two species of Opisthoppus.