the leaves may be reduced in size, converted into thorns, or entirely dispensed with, in order to check rapid evaporation, they may be covered with silky or felted hairs, a modification which produces the same result, or their internal tissue may be succulent or mucilaginous. In the plants of the Panjab plains there is no difficulty in recognising these features of a drought-resisting flora. Schimper's map shows in the north-east of the area a wedge thrust in between the plains' desert and the dry elevated alpine desert cut off from the influence of the monsoon by the lofty barrier of the Inner Himalaya. This consists of two parts, monsoon forest, corresponding roughly with the Himalayan area Cis Ravi above the 5000 feet contour, and dry woodland of a semi-tropical stamp, consisting of the adjoining foot-hills and sub-montane tract. This wedge is in fact treated as part of the zone, which in the map (after Drude) prefixed to Willis' Manual and Dictionary of the Flowering Plants and Ferns, is called Indo-Malayan, and which embraces the Malayan Archipelago and part of North Australia, Burma, and practically the whole of India except the Panjab, Sindh, and Raj put ana. In Drude's map the three countries last mentioned are included in a large zone called "the Mediterranean and Orient." This is a very broad classification, and in tracing the relationships of the Panjab flora it is better to treat the desert area of North Africa, which in Tripoli and Egypt extends to the coast, apart from the Mediterranean zone. It is a familiar fact that, as we ascend lofty mountains like those of the Himalaya, we pass through belts or regions of vegetation of different types. The air steadily becomes rarer and therefore colder, especially at night, and at the higher levels there is a marked reduction in the rainfall. When the alpine region, which in the Himalaya may be taken as beginning at 11,000 feet, is reached,
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HERBS, SHRUBS, AND TREES