THE BAOBAB TREE. 
35 
bat sparingly clad witk scanty lichens and mosseSj they 
are there covered with stately bi'oineUaa and wondrous 
orchids. Sweet-snielUiig vanillas and passifloms wind 
round the giants of the forest, and large flowers break 
forth from their rough bark, or even from their very 
roots. 
The number of known plants is estimated at about 
200,000, and the greater part of this vast multitude of 
species belongs to the torrid zone. But if we consider 
how very imperfectly these sunny regions have as yet 
been explored — that in South America enormous forest 
lands and river basins have never yet been visited by a 
naturalist — that the vegetation of the greater part of 
Central Africa is still completely hidden in mystery — 
that no botanist has ever yet penetrated into the interior 
of Madagascar^ Borneo, Kew Guinea, South-Western 
China, and Ultra-Gangetic India — and that, moreover, 
many of the countries visited by travellers have been but 
very superficially examined — we may well doubt whether 
even one-fourth part of the tropical plants is actually 
known to science. 
After these general remarks on the variety and exuber- 
ance of tropical vegetation, I shall now briefly notice those 
plants which, by their enormous size, their singularity of 
form, or their frequency in tlie landscape, chiefly charac- 
terise the 'various regions of the torrid zone. 
The African Baobab, or monkey-bread tree, may justly 
be called the elephant of the vegetable world. Near the 
village Guraer, in Fassokl, Russegger saw a baobab thirty 
feet in diameter and ninety-five in circumfcrence ; the 
horizoDtally outstretched branches were so large that 
the negroes could comfoiiably sleep upon them. ITio 
Venetian traveller Cadamosto (1454) found, near the 
mouths of the Senegal, baobabs measuring more than a 
hundred feet in circumference. As these vegetable giants 
are generally hollow, like our ancient willowsj they are 
frequently made use of as dwellings or stables; and Dr. 
