Abstract: A study was conducted on the leaf anatomic plasticity of white clover (Trifolium repens L.) in response to the heterogeneous habitats, and on the legume leaf anatomic characteristics under different light intensities. Results show that the white clover leaf structure boasts plasticity, more particularly the leaf epidermis and mesophyll, though the leaf middle vein remains relatively stable. Under full sunlight, the white clover leaves share characteristics of sun-facing plants: such as thicker leaf blades, plate outer cells wall in upper epidermis, dense stomas, developed palisade tissue with densely arranged cylinder palisade cells, thinner spongy tissue with tiny and loosely arranged cells, and thicker mid-ribs. Whereas under thinned sunlight, the legume leaves exhibit features of those of shade plants, like thin leaf blades, lens-like upper epidermis cells, loosely arranged stomas, reductive palisade tissue with irregular or funnel-shaped cells, rich spongy tissue of large-sized and densely ranged cells, and thin mid-ribs. Nonparametric correlation analysis indicates that the thickness of upper epidermis and thickness of spongy tissue negatively correlate to the relative light intensity, while stoma density of upper epidermis, thickness of palisade tissue, thickness ratio of palisade and spongy tissue, length and width ratio of palisade cells, and thickness of middle vein positively correlate to the relative light intensity. Leaf anatomy plasticity may contribute to the high ecological adaptation of this widespread species.

Key words: Trifolium repens, Leaf blade, Anatomic characteristics, Phenotypic plasticity, Light intensity

摘要： 探讨不同光照强度下白三叶叶片解剖特征,叶片可塑性及其对光强环境的响应。结果表明:白三叶叶片结构具有一定的可塑性,其中表皮和叶肉的可塑性较大,而中脉则相对较为稳定;在全光照条件下,叶片为阳生叶特征,叶片较厚,上表皮外切向壁平展,气孔密度大,栅栏组织发达,栅栏细胞长柱形,排列紧密,海绵组织较薄,细胞较小,排列疏松,中脉较厚;在弱光照条件下,叶片为阴生叶特征,叶片较薄,上表皮细胞凸透镜状,气孔密度较小,栅栏组织极不发达,栅栏细胞不规则或漏斗形,海绵组织发达,细胞较大,排列紧密,中脉较薄;非参数相关性分析结果表明,上表皮厚度、海绵组织厚度与相对光照强度呈显著负相关,而上表皮气孔密度、栅栏组织厚度、栅栏组织海绵组织厚度比、栅栏细胞长宽比和中脉厚度等性状与相对光照强度呈显著正相关。

关键词: 白三叶, 叶片, 解剖特征, 表型可塑性, 光照强度