Development of stomata and foliar structure of some Magnoliaceae

Abstract

The development of stomata and other interesting anatomical features of leaves, sheathing stipules and perianth lobes of 5 species of Magnolia and 4 species of Michelia were studied. Very often the mature foliar stomata are paracytic with 2 parallel subsidiaries and 1 or more parallel encircling cells but the stomata in the sheathing stipules and perianth lobes are usually anomocytic. A fairly constant feature of the foliar stomata of these plants is the partial overlapping of the subsidiary cells by the guard cells. Epidermal cells of a few species contain calcium oxalate druses. In Magnolia grandiflora and M. pumila the epidermal cells possess peculiar rod-shaped bodies of uncertain chemical nature. Polygonal or lobed thick walled brachysclereids occur singly or in groups in the various investigated species. Thin walled vesiculose sclereids are found in the leaves of all plants but they are absent in other organs of some species. The 2 parallel subsidiary cells and encircling cells of stomata develop from the same initial. The development of stomata is, therefore, typically mesogenous (syndetocheilic). According to Rao (1939) the encircling cells in some of these plants are formed by divisions of the subsidiary cells and although this is partly true the encircling cells of a majority of stomata are formed directly from the stomatal meristemoids. According to Paliwal & Bhandari (1962) the anomocytic stomata of the perianth lobes of Magnolia grandiflora, M. stellata and Michelia champaca are haplocheilic which implies that they are perigenous. However, we find that the irregular ring of cells around the guard cells of stomata in these parts and in the sheathing stipules, develop as a result of divisions in the mesogene subsidiary cells indicating thereby that these stomata are mesogenous and their development is essentially similar to that of foliar stomata.