046 REPORT OF THE HARVARD AFRICAN EXPEDITION 
several ferns of which Pteris Mannii is as frequent as any. Piper guineen- 
sis, used by the natives to flavor their rice, grows very luxuriantly, if not im 
ereat numbers, up the trunks of the higher trees, as does Dichapetalum pallidum. 
Lianes are few in number and for the same reason conspicuous. Of these 
at least three species were collected: Dalbergia oblongifolia, Oxymitra gracilis, 
and Calpocalyx brevibracteatus. The last species, growing in this locality is a 
liane, yet along the river’s edge it is a slender tree thirty to forty feet high. 
The forest trees through which only diffuse light penetrates to reach the ground, 
are essentially the same as those that grow along the edge of the river, although 
a member of the Leguminoseae that has pinnate leaves and of which the flow- 
ers are densely arranged to form slender spikes four to seven inches long, is 
a dominant tree in the wetter places. It reaches a height of about two hundred 
feet and then its heavy limbs are so branched that a flat-topped crown is 
produced. The bole of this tree, grayish and relatively smooth, is about two 
and one-half feet in diameter at shoulder level. Another tree (No. 422) with a 
somewhat stilted and distinctly buttressed base probably belongs in the genus 
Chrysophyllum. On the upper limbs of this tree, an orchid belonging to the 
genus Bulbophyllum grows in great abundance and, incidently, serves as feeding 
ground for the white-faced monkeys. It is difficult to make out whether it 
is the young shoots that are eaten or the insects that are found among the 
roots. At the upper border of the swamp, the trunks of the trees are draped 
by the foliage of the climbing aroids, Rhektophyllum mirabile and Cercestis sp. 
Here also grow such low trees as Cola lateritia and Antidesma membranaceum, 
twenty to forty feet high. 
The trees of the upper levels are not as tall as those of the swamps. They 
seldom exceed one hundred and twenty-five feet. Also the foliage is less dense 
and thus light is permitted to reach the forest floor in greater quantities, thereby 
favoring the growth of a greater number of low trees, bushes and herbs. Here 
Afrodaphne euryneura attains a height of fifty feet, and Cola acwminata about 
thirty-five feet. A species related to C. acwminata, and previously found on 
the hilltops near the Du River is C. pachycarpa. There are many species of 
trees or shrubs that do not reach twenty feet. Of those determined to date, 
Acioa Barteri and Uvaria spectabile are usually that tall, but the remainder 
are between six and fifteen feet high. To this class belong Popowia Vogelii, 
Antidesma venosum, Microdesmis puberula, and Rinorea liberica, the last a mem- 
ber of the violet family. Two of the more conspicuous forms are Ouratea 
flava, an abundant and showy species with large suberect panicles of yellow 
flowers, and O. elongata, a plant worthy of cultivation in any greenhouse. This 
latter species is less bushy than its relative. The stem is four to five feet long, 
simple, and erect. On the upper part of the stem are produced large, slightly 
recurved, lanceolate leaves, at the base of which humus collects and serves as 
a source of nutrition, for roots that arise from the base of the petioles, pene- 
trate it in all directions. The flowers of this species are also borne in a large 
panicle, sometimes three or four, but the panicle in this case is drooping and 
is surmounted by a pair of leafy bracts. 
