Vegetation
The characteristic distribution of vegetation on the mountains of Afghanistan is worthy of attention. The great mass of it is confined to the main ranges and their immediate off-shoots, whilst on the more distant and terminal prolongations it is almost entirely absent; in fact, these are naked rock and stone.
Take, for example, the Safed Koh. On the alpine range itself and its immediate branches, at a height of 6000 to 10,000 ft., we have abundant growth of large forest trees, among which conifers are the most noble and prominent, such as Cedrus Deodara, Abies excelsa, Pinus longifolia, P. Pinaster, P. Pinea (the edible pine) and the larch. We have also the yew, the hazel, juniper, walnut, wild peach and almond. Growing under the shade of these are several varieties of rose, honeysuckle, currant, gooseberry, hawthorn, rhododendron and a luxuriant herbage, among which the ranunculus family is important for frequency and number of genera. The lemon and wild vine are also here met with, but are more common on the northern mountains. The walnut and oak (evergreen, holly-leaved and kermes) descend to the secondary heights, where they become mixed with alder, ash, khinjak, Arbor-vitae, juniper, with species of Astragalus, &c. Here also are Indigoferae rind dwarf laburnum.
Lower again, and down to 3000 ft. we have wild olive, species of rock-rose, wild privet, acacias and mimosas, barberry and Zizyphus; and in the eastern ramifications of the chain, Chamaerops humilis (which is applied to a variety of useful purposes), Bignonia or trumpet flower, sissu, Salvadora persica, verbena, acanthus, varieties of Gesnerae.
The lowest terminal ridges, especially towards the west, are, as has been said, naked in aspect. Their scanty vegetation is almost wholly herbal; shrubs are only occasional; trees almost non-existent. Labiate, composite and umbelliferous plants are most common. Ferns and mosses are almost confined to the higher ranges.
In the low brushwood scattered over portions of the dreary plains of the Kandahar table-lands, we find leguminous thorny plants of the papilionaceous sub-order, such as camel-thorn (Hedysarum Alhagi), Astragalus in several varieties, spiny rest-harrow (Ononis spinosa), the fibrous roots of which often serve as a tooth-brush; plants of the sub-order Mimosae, as the sensitive mimosa; a plant of the rue family, called by the natives lipad the common wormwood; also certain orchids, and several species of Salsola. The rue and wormwood are in general use as domestic medicines---the former for rheumatism and neuralgia; the latter in fever, debility and dyspepsia, as well as for a vermifuge. The lipad, owing to its heavy nauseous odour, is believed to keep off evil soirits. In some places, occupying the sides and hollows of ravines, are found the rose bay (Nerium Oleander), called in Persian khar-zarah, or ass-bane, the wild laburnum and various Indigoferae.
In cultivated districts the chief trees seen are mulberry, willow, poplar, ash, and occasionally the plane; but these are due to man's planting.
Reference
Much of the material in this article comes from the CIA World Factbook 2000 and the 2003 U.S. Department of State website. The text comes from part of the entry on Afghanistan in a 1911 encyclopedia