Studies On Micromorphology Of Melampyrum L.

Melampyrum L. is a genus of annual hemiparasitic herbaceous plants, consisting of about 20 species in the Northern hemisphere. There is a great deal of variation in certain characters, especially in leaf and bract morphology, and many differences exist in the disposal of taxon. So far, some work carried on by oversea scientists were focused on biochemistry physiology and ecology of Melampyrum L., and in China, there were only some researches about pharacognostical identification besides some taxon recordations from Chinese floras. However, there were few systematic studies on Melampyrum L. The micromorphological characters of 13 species and 4 varieties of Melampyrum L. over the world were studied detailedly by LM, SEM, statistic analysis and field investigation in this paper. It might provide some valuable experimental datas for the systematic evolution relationship of Melampyrum L., the adaptation mechanism to the ecological environment, and the characters and mechanism of semiparasite. The results were as follows:Firstly, the leaf epidermis of 22 samples representing 13 species and 4 varieties were investigated under both light microscope (LM) and scanning electron microscope (SEM). It was shown that the leaf epidermal cells were usually irregular in shape. The patterns of anticlinal walls were sinuolate, sinuous, sinuate or double-sinuate. The stomatal apparatus which mostly distributed in lower epidermis were often anomocytic. Both nonglandular hairs and glandular hairs were on the epidemis, but there were more glandular hairs on the abaxial epidermis than those on the adaxial epidermis, the nonglandular hairs had neoplasitic process under SEM. The inner margin of the outer stomatal rim was nearly smooth, sinuolate or sinuous, and the cuticular membrane was striate. Characters of the leaf epidermis in Melampyrum L., such as patterns of anticlinal walls, shapes of guard cells and inner margin of the outer stomatal rim, appeared to be constant with species and thus could be used for distinguishing some species. The results also suggested that the patterns of anticlinal walls and the characters of stomatal apparatus might provide some valuable evidences for systematic relationship and evolutionary trend.Secondly, 15 morphological characters of 2 species and four populations in M. roseum and M aphraditis were studied by numerical analysis. The results showed that: (1)The morphological characters showed certain var..iation within 2 species and 4 populations, the order according to the variation level of them was Tianzhushan population (M. aphraditis)