168 REPORT OF THE HARVARD AFRICAN EXPEDITION 
by the character of the soil and also by the exceedingly severe showers which 
tend to expose the roots. The traveller upon the trail is continually reminded 
of these surface roots and must raise his foot continually to step over them. 
The tendency of the roots of many of the trees to spread out rather than grow 
downward is also clearly the result of the geological structure of the deeper 
layers of the soil. As we have already pointed out, the soil of Liberia, which 
has such an important influence upon the character of the flora, shows in dif- 
ferent parts of the country considerable variations in consistency and in its 
mineral and organic characters. 
As might be expected, one finds affinities between the Liberian flora and 
the tropical southern and eastern Asian flora and even the South American. 
The distribution of Maschalocephalus dinklaget, named after its discoverer, 
Mr. Dinklage, which is the single representative of the South American Rapata- 
eae found in Liberia, has been particularly studied by Dr. Linder (Map VII). 
This plant itself is illustrated in the photograph No. 437. 
By travelling up the rivers of Liberia by canoe or launch, and occasionally 
making an excursion into the surrounding country, one can obtain a very in- 
teresting idea of many of the floral characteristics of the country. Nearer the 
coast the tidal streams are frequently lined with the mangrove, Rhizophora 
racemosa, and the other vegetation characteristic of the vicinity of mangrove 
swamps. One of the commonest of the floral plants along the banks of rivers 
is Cyrtosperma, with large leaves and flowers in spathes of a purple color with 
yellowish green streaks. As one ascends the river the Pandanus candelabrum 
(No. 185), or screw pine, with its gigantic aérial roots and spinous leaves 
becomes the most striking feature of the landscape. 
Still further inland the banks and adjacent marshy districts are covered 
with Raphia vinifera (No. 136), the piassava palm, so important commer- 
cially and in the domestic life of the natives. The larger oil palm, EHlaeis guine- 
ensis (No. 138), of even greater commercial importance, prevails in great 
abundance in less marshy areas. Another striking palm frequently observed is 
the Calamus or rattan palm (No. 137), with its central fronds with whip-like 
stems, which grow out much like a long creeper, and which reach high above 
the surrounding vegetation or climb up the highest trees. The Borassus palm 
so abundant in many other parts of Africa, is conspicuous by its absence. It 
apparently does not occur in the interior, although its occurrence nearer the 
coast has been noted by Johnston and others. 
In comparison with the flora observed along a number of South American 
tropical rivers the comparatively few species of palms observed in Liberia is 
a striking feature. In Liberia we know only some half-dozen species, whereas 
in the Amazon region, for example, the species of palms are in comparison 
exceedingly numerous. Indeed, besides the three just mentioned, only the 
coconut palm, Cocos nucifera, and wild date palm, Phoenix reclinata (No. 403), 
have been found in the country. The date palm which grows in low dense bushes, 
produces the sweet but coarse wild date, occasionally eaten by natives, but 
more commonly considered the food of elephants. The fibers from the midrib 
