‘PHYSIOLOGY. 269 
Besides these varieties of ligneous plants, there are 
many which make’a transition from one to the other. 
§ 263. 
The Palms present the most beautiful of all lig- 
neous stems, which kind nature has given to the 
warm climates exclusively. But after them, the par- 
ticular growth of some trees in the West Indies, 
which are not of the palm tribe, deserve notice. 
To those belong the species Theophrasta and Spa- 
thelia. They have a simple, very high, branchless 
stem, which in its whole surface is ornamented with 
bundles of leaves. ‘The appearance of a landscape 
with groupes of such trees must be very singular 
indeed. | 
A tree which grows in Africa, on‘ the Senegal, 
presents the most irregular appearance, and which 
‘fio doubt is the thickest tree on the globe. It is the 
Adansonia digitata. Its stem is only ten or twelve 
feet high, but so thick that its diameter is found to 
be from 25 to 30 feet. Its circumference, therefore, 
is from about 75 to 90 feet. Its top is very re- 
markable, for numerous and thick branches, of from 
30 to 60 feet in length, run out from it in all di- 
rections. We ought, therefore, not to be surprised 
that sometimes the hollow trunk of the Adansonia is 
the abode of several negro families. 
Not less wonderful is the tree called Rhizophora 
mangle, which bends its branches perpendicularly to 
the ground, and changes them into stems, so that 
one single tree covers the muddy rivers under 
the tropics of Asia, Africa and America, for more 
than 
