Page:The Journal of Indian Botany.djvu/360

314 margin of damp soil between the water of pools and the extensive dry meadows that characterize the plains. It is perhaps the most difficult stage of all to unravel, because its green vegetation forms such an attractive grazing ground, and because it shifts position with the change of seasons. During the rainy season it encroaches on the dry meadow, and during the hot season it recedes far toward the center of the pools, or disappears entirely. I have found just one place where the water relations are sufficiently constant that the wet meadow is permanent enough to study in detail (Fig. 10). By supplementing this small area with observations on other places, it is possible to give a fairly consistent account of the wet meadow stage.

The typical association is characterized by a large development of Cyperaceae and Cynodon dactylon Pers. About the pools that are subject to extreme fluctuation in water level there is also intensive cultivation and grazing (Fig. 9), and the Cyperaceae and Cynodon are about the only plants of consequence that can survive from year ot year. Many of these plants are able to adapt themselves to a wide range of conditions, from shallow water to relatively dry banks. Cynodon dactylon, for example, is specially typical of later stages of the wet meadow, yet it can grow fairly well when completely submerged, and persists in many places into all but the dryest of the dry meadows. The following is a list of the common plants of the wet meadow is arranged approximately in the order of succession : Scirpus maritimus, S. quinquefarius Ham., Cijperus difformis L., Fimbristylis diphylla Vahl., Amniannia baccifera L., Ranunculus sceleratus L., Cynodon dactylon, and Eragrostis tenella R. and S. Usually Scirpus quinquefarius, Fimbristylis and Cynodon determine the general aspect of this stage (Fig. 10).

Where the wet meadow zone shifts back and forth with the change of season, where erosion produces fresh soil surfaces, and where the human factors are very intensive, perennial plants are replaced by an association of short-lived annuals. These come up from seed where- ever conditions are favorable, and persist as long as there is sufficient moisture. This group of wet meadow annuals reaches its greatest development during the late cold season and early hot season. It is such plants as these that make the seasonal succession so conspicuous. They are for the most part small plants, and contribute little toward the development of the permanent flora : Jimcellus pygmacus Clarke, Scirpus michelianus L,. Potentilla supina L., Gnaphalium indicum L., Grangea madcraspatana Poir., Bumex dentatus L., Ranunculus sceleratus, Polygonum plebsjum Br., Alternanthera scssilis Br., Bergia ammannioides Robx., Biccia sanguinca, Hydrolea zeylanica Vahl., and Glossostigma spathulatum Arn.