| Abstract: | The distribution density of oil cells, the morphology and structure of both oil andmucilage cells, and their localization in the mesophyll of 112 species, 5 varieties and 2 formsin 21 genera of the Lauraceae are comparatively studied with the methods of tissue clearingand paraffin sectioning. The results show that there exist obvious differences of the distribution density of oil cells among the species in the Lauraceae. The presence of oil cells and mucilage cells is found to be a marked anatomical feature of the leaves in most of the plants inthe Lauraceae. Their distribution in the mesophyll can be divided into 4 types: type Ⅰ , inwhich only oil cells are present; type Ⅱ, in which both the oil and mucilage cells are present; type Ⅲ, in which only mucilage cells are present; type Ⅳ, in which neither oil cellsnor mucilage cells are present. The distribution density of oil cells, the distribution types ofoil cells and mucilage cells and their localization in the mesophyll are of some taxonomic valueat the specific level in the Lauraceae. In the whole Lauraceae or in some large genera, theevolutionary trend of the distribution types of oil cells and mucilage cells might be as follows:type Ⅰ → type Ⅱ →type Ⅲ →type Ⅳ. The characteristics of the 4 distribution types of oilcells and mucilage cells support the division of two subfamilies in the Lauraceae. |
