Thursday, August 30, 2012
Plant Ground Tissues
Plant ground tissues consist of unspecialized cells; the most common kind is called parenchyma, which is composed of cells that are mainly of one kind and usually have thin walls. Frequently, stems contain two kinds of parenchyma. One, the cortex, occupies a peripheral position within the stem, just under the epidermis, whereas the other, the pith, is found in the center of many stems. In leaves parenchyma cells are filled with chloroplasts and do most of the photosynthesizing. Some parenchyma cells retain the capacity to divide and may become meristems. Cortical parenchyma of stems may contain cells modified for support, whereas other parenchymal cells may function in food storage, such as the parenchyma of the potato tuber. An importan feature of many parenchyma tissues is that the cells are loosely packed together and ha ve interconnecting air spaces in between.