The sub-Himalayan tract is a loose term for a very long range of low hills and valleys that fringe the great Himalayan highland on its southern and western edge. In the map you can see the heights of the Himalayan area in browns and grays, denoting elevations above, often well above, 1500 meters or so. If you look closely you can see between the green plains and the gray mountans a tiny fringe of hills in a beige color. This is a lowland area, and though it looks narrow and almost insignificant here, it is thousands of kilometers long, providing a lot of habitat for a lot of plants and animals, and it is one of India’s many fascinating biological realms.
None of the extant woods in this area support any moringas that seem even possibly wild. The dominant lowland forest type in the area is a kind called sal forest. Sal is the common name for a member of the Dipterocarpaceae family called Shorea robusta. This is very exciting for a botanist because dipterocarps are very important members of the forests of eastern and southern Asia. Some of the world’s tallest trees are, or probably were anyway before they were cut down, dipterocarps. There are just a few dipterocarps in the Americas, only in northern South America, and even there they are rare, so it is a treat for a botanist from this side of the world to see them. Sal forests are especially interesting because they form if not pure forests they do a good job of trying. Most tropical forests (with the exception of most Australian inland ones, which are spectacularly poor in species) are very diverse, with hundreds or at least dozens of species at any one site, far more than in any temperate forest. So seeing tropical forests in which a single species predominates is a very unusual phenomenon, and a very perplexing one. This is why in the photo below I have an even goofier smile than usual. What also blew my mind were the chir pine Pinus roxburghii that grew on the steepest, most eroded outcrops and slopes in the midst of the sal forest.
So much for the forests around Dehradun, the Shivalik range, and the plains of Saharanpur (and many other lowland localities in the area besides). Maybe the moringas were instead to the north, into the Himalayan mass proper. There were many clues that suggested that this might be the case. Duthie says that moringa grows wild in the “outer Himalaya,” Stewart and Brandis say “Wild in the lower Himalaya.” At the Botanical Survey of India herbarium there was even a specimen from a place called Suni, in Shimla District, Himachal Pradesh, with the label reading “Amidst boulders on exposed sunny faces of hill…growing in association with Phoenix sp. [a palm].” Sure sounds wild. And though most people think snow and ice when they think of the Himalaya, there are deep fingers of relatively lowland habitat that penetrate far into the interior. Suni, for example, sits below 700 m elevation, high for a moringa but hardly highland. Maybe M. oleifera grew wild in these remote, rugged, hidden pockets of lowland.