Plant Explorations of G. Wilson-Browne, S. J., in British Guiana. I. Kanuku Mountains

Abstract

The Kanuku Mountains lie in the extreme southern part of British Guiana; latitude 30N. passes through the most southerly portion. They are divided into a western and an eastern mass by the Rupununi River, which flows through them in a northeasterly direction. The western Kanukus lie between the Takutu and Rupununi Rivers; the eastern Kanukus between the Rupununi River and the headwaters of New River, a tributary of the Courantyne. The present collection was made entirely in the western Kanukus between August and December 1948; the eastern mass remains botanically unknown and geographically unmapped. The Guyana Highlands are for the most part sedimentary deposits of sandstone on an igneous base; the Kanukus differ in being entirely granitic and may, perhaps, be more nearly comparable with the Wilhelmina Mountains of Surinam. Apart from the courses of mountain streams and perpendicular precipices, such as on Iramaikpang or Cock of the Rock, the granite is entirely covered with a stiff, red, lateritic clay. On the steeper mountains, such as Tiger Mountain, the clay is entirely bare, but in the valleys and less abrupt ascents it is covered with a rich humus. The ability of this clay to remain on extremely steep formations permits the mountains to be clothed to the summit with heavy bush, hence their Wapisiana name "Kanuku" or "forest." The maximum elevation is in the neighborhood of 3000 feet, a height attained by Mt. Wabu-ak and Mt. Iramaikpang at least. Dr. A. C. Smith spent three months collecting in the western Kanuku Mountain region immediately after the completion of the Terry-Holden Expedition of 1937-1938, on which he was the botanist. His desire that further examination of the interesting flora of the Kanukus might be stimulated by his work there has, I hope, been fulfilled in some measure by the present collection. Two sites for base camps were selected for the present collection; the first was on the shoulder of Mt. Wabu-ak, a conspicuous dome-shaped mountain about eight miles north of Mt. Bulakuk-taba-ial. From this base we were able to explore the surrounding Mts. Waiwitau, Macubere, Tiger, and Baboon. A large clearing on Mt. Wabu-ak afforded us fresh air and sunshine, and pack oxen with our supplies and equipment somehow managed to scramble to the shoulder of the mountain, 650 meters above the level of the savanna. All numbers cited from Wabu-ak were collected in this area of about 64 square miles, a rough rectangle formed by the mountains mentioned above. After the camp had been established I had the pleasure of Mr. D. B. Fanshawe's company for a short time. It was in his company that I later crossed the mountains from Mt. Wabuak to a range not far from Mt. Nappi and had he been able to stay for a longer period the collection would undoubtedly have been more valuable.2