The Indian Lotus, Nelumbo nucifera GAERTN. has two kinds of leaves. They are the standing leaf that stands at the surface of the water and the floating leaf that rises to the surface of the water. The first leaf which is formed in the first node of the main stem growing out of a terminal bud of the seed-rhizome (a storage stem) becomes the standing leaf, or the floating leaf. What conditions will make the first leaf in the first node of the main stem the standing leaf, or the floating one?
The present investigation is aimed at the effect of the amount of applied fertilizer (zero, standard, and double) and shading treatment with cheesecloth (roof type shading and tunnel type shading) on these leaves. The result may be summarized by the following points:
1. Both at the control and at the roof type shading, the first leaves formed in the first node of the main stem have become the standing leaves. But by the amount of the standard and double fertilizer applied with the tunnel type shading, they have become the floating leaves respectively, where the relative humidity was remarkably higher than other treatment.
2. The thickening grade of the cell wall, that composes the hypodermis in the petiole of the first leaves of the main stem, was more remarkable in the standing leaves than in the floating leaves. The Phloroglucin Hydrochloric Acid Reaction was in proportion to the thickening grade of the cell wall; namely in the remarkable thickening in the petiole of the standing leaf the Phloroglucin Hydrochloric Acid Reaction was remarkable. Slight thickening at the petiole of the floating leaf was not remarkable.
3. The thickening grade of the fibrous cell, that composes the hypodermis in the petiole of the first leaves of the main stem, was more remarkable in the standing leaf than in the floating leaf. The morphology of the fibrous cell in the petiole was almost the same as in both the standing leaf and floating leaf. The thickening of the fibrous cell in the standing leaf was remarkable and in the floating leaf it was slight. It was found that the histological difference of the standing leaf and floating leaf depended upon the thickening grade of the fibrous cells.