Structural features of leaf epidermis and stem of different populations of Solidago canadensis and CCA analysis of the structural features with environmental factors.

The structural features of leaf epidermis and stem transection of 45 populations of Solidago canadensis L.collected in East China and transplanted in the same habitat were comparatively observed.The correlation of population distribution,structural features of leaf epidermis and stem with environmental factors were studied by canonical correspondence analysis(CCA).The results show that trichomes on upper and lower epidermis are all uniseriate multicellular non-glandular trichomes,and the trichome density of lower epidermis is higher than that of upper epidermis.The cell shape of upper epidermis is polygonal and the anticlinal wall is straight or arched,while the cell shape of lower epidermis is usually irregular or polygonal and the anticlinal wall is slightly straight,arched or sinuolate.Stomata barely distribute on upper epidermis and mostly distribute on lower epidermis.Stomatal apparatus is anomocytic type,and stomatal shape is mostly subcircular.The trichome density of epidermis,stomatal density,length and width are significantly different among populations.Populations distributing in dry habitats have higher trichome density of epidermis and smaller stomata,while populations distributing in humid habitats have lower trichome density of epidermis and bigger stomata.The stem transection is composed of epidermis,cortex and central cylinder.The structures of epidermis and cortex in stem are not significantly different among different populations,and there are significant differences in the vascular bundle number(8.05-13.39 mm-1) and percentage of pith area(25.7%-49.5%).There are differences in the plasticity index of structural features of leaf epidermis and stem among different populations,in which the mean plasticity index of stomatal density is the highest(0.38),and that of percentage of pith area is the lowest(0.13).The results of CCA analysis show that the structural features of leaf epidermis and stem have a greater correlation with soil humidity and latitude,and there is a positive correlation between density,length,width of stoma and soil humidity.The vascular bundle number,density of epidermal trichome and percentage of pith area are negatively correlated with soil humidity and latitude,and the correlation of population distribution with soil humidity and latitude in location is great.The adaptive differentiation of S.canadensis in morphological features benefits its invasion in different habitats,and those variation of morphological features may be maintained by vegetative propagation to increase success rate of invasion.