(THE ecology of the UPPER GANGETIC PLAIN. 317
perhaps the first to assume a place of prominence, and is the most xerophytic. It is closely followed in point of time and in importance by Cenchrus and the two Andropogons. The remaining species are of secondary importance. Along with the grasses of such a protected area there come in a new set of herbaceous annual and perennial dicotyledons, such as Rhynchosia minima DC, Alysicarpus bupleuri- folius DO., and Grotalaria mysorcnsis Eoth. At times one finds a straggling Zizyphus jujuba or Z. rotundifolia, Lamk., an Acacia arabica, or some other woody plant, but they are not numerous.
That the grasses cf the protected meadows actually are the result of protection, and not a matter of special soil or moisture relations, is indicated by the fact that they are found all over the area, wherever grazing is lessened or difficult. They flourish even on the dryest of the cliffs, in positions where cattle and goats cannot readily reach them. They already potentially occupy the area, and await only protection from excessive grazing to develop into a more advanced plant formation.
The areas of thorny shrubs and small trees, which are used to give name to the stage following the dry meadow, are remnants of a pioneer type of forest that has persisted on tracts that have remained uncultivated for considerable time (Figs. 13 and 14). In some places the growth is scattering and savannah-like, in others it is more ' dense (Fig. 15) ; but everywhere the ground is occupied by a typical dry meadow association of grasses (Fig, 13). The principal species comprising this pioneer forest are Capparis sepiaria L., Acacia arabica Willd., A. leucophloea Willd., Balanites aegyptica Delile, Justicia adhatoda L., Flacourtia sepiaria Roxb., Jatropha gossypi- folia L., Zizyphus jujuba Lamk. and Alangium lamarckii Thw. Most of these plants are conspicuously thorny, and are thus protected from complete destruction by grazing animals. Justicia and Jatropha, are the only abundant ones with no obvious protection, yet animals will not eat them even when other vegetation is scarce ; the latter has been introduced from Brazil, and is now completely naturalized and competes successfully with the other plants of the formation. Alangium also is sparingly eaten. Balanites is the most successful as a pioneer in dry unpromising conditions, though the Acacias are not much behind it in this respect.
Some distance north and west of Allahabad Butea frondosa Roxb., becomes one of the most important of the thorn scrub trees ; there are only straggling outliers to be found in the local area. It is not thorny, but is the ecological equivalent of the thorn scrub plants.
Wherever such woody vegetation occurs it is more or less con- stantly cut for fuel, and the smaller plants are pruned by grazing
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