. Botany for agricultural students . Botany. CELLULAR STRUCTUKE OF LEAVES 249 NUMBER AND DISTRIBUTION OF STOMATA PER SQUARE MILLIMETER OF LEAF SURFACE Plant Upper Surface. Lilac (Syringa vulgaris) Alfalfa (Medicago sativa) Bean (Phaseolus vulgaris) Tomato (Lycopersicum esculentum) Cherry Pumpkin (Cucurbita pepo) Oats (Avena sativa) Corn (Zea Mays) Although stomata are most numerous on leaves, they occur in Flowering Plants wherever there is green tissue to be supplied with gases. They are common on fruits, green twigs of trees, and are present on nearly all parts of the aerial stems of herba-
. Botany for agricultural students . Botany. CELLULAR STRUCTUKE OF LEAVES 249 NUMBER AND DISTRIBUTION OF STOMATA PER SQUARE MILLIMETER OF LEAF SURFACE Plant Upper Surface. Lilac (Syringa vulgaris) Alfalfa (Medicago sativa) Bean (Phaseolus vulgaris) Tomato (Lycopersicum esculentum) Cherry Pumpkin (Cucurbita pepo) Oats (Avena sativa) Corn (Zea Mays) Although stomata are most numerous on leaves, they occur in Flowering Plants wherever there is green tissue to be supplied with gases. They are common on fruits, green twigs of trees, and are present on nearly all parts of the aerial stems of herba- ceous plants. On the older twigs and trunks of trees, the stomata are represented by the lenticels which are the structures into which stomata are transformed as the stem becomes enclosed in bark. The stomata are distorted and transformed into lenticels partly by the stretching of the bark and partly by the tissue which grows up from beneath and crowds into the stomatal openings. In order to get a view of the epidermis in cross section and to study the chlorenchyma and veins of a leaf, a thin section must be made and highly magnified as shown in Figure 232. In this view an ordinary epidermal cell is rectangular, has a large central cavity separated from the cell walls by only a thin layer of proto- plasm, and has the outer wall more thickened than those within. The continuity of the epidermis is interrupted by the stomata, each of which opens into an air chamber in the mesophyll just beneath. The chlorenchyma is composed of thin-walled cells, having thin layers of protoplasm in which the characteristic green bodies (chloroplasts) are located. In most horizontal leaves, the cells of the chlorenchyma are differentiated into two distinct groups, the palisade and the spongy tissue. The palisade tissue is next to the upper epidermis and consists of one or more rows of compact elongated cells in which chloroplasts are especially Please note that these images are extracted
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
