EXCURSION ON THE RIO NEGRO. 337 
lias its leaves arranged according to the fraction of -f s ; but, 
though the crown consists of several cycles of leaves, they 
do not form a close head, because the older ones become 
pendent, while the younger are more erect. The Pupunha, 
or peach palm (Guilielma), follows the Phyllotaxis of -f^ ; 
but in this instance all the leaves are evenly arched over, 
so that the whole forms a deep-green vault, the more beau- 
tiful from the rich color of the foliage. When the heavy 
cluster of ripe, red fruit hangs under this dark vault, the 
tree is in its greatest beauty. As the leaves of this palm 
are not so closely set in the younger specimens as in the 
older ones, its aspect changes at different stages of growth ; 
the leaves in the younger trees being distributed over a 
greater length of the trunk, while, in the adult taller ones, 
they are more compact. This arrangement is repeated in 
the Javari and Tucuma (Astrocaryum) ; but in these the 
closely- set leaves stand erect, broom-like, at the head of the 
long stalk. In the Mucaja (Acrocomia) the leaves are ar- 
ranged according to the fraction J|. Thus, under the 
same fundamental principle of growth, an infinite variety is 
introduced, among trees of one order, by the slight dif- 
ferences in the distribution and constitution of the leaves 
themselves. In the Musacea?, or Scytamineae, the Bananas, 
another order of the same class of plants, a diversity equally 
remarkable is produced in the same way, namely, by slight 
modifications of this fundamental law. What can differ 
more in appearance than the common Banana (Musa par- 
adisiaca), witli its large simple leaves, so loosely arranged 
around the stem, so graceful and easy in their movements, 
and the Banana of Madagascar (Ravenala madagascariensis), 
commonly known as the Traveller's tree, which, like the 
Bacc&ba of Para, has its leaves alternating regularly on op- 
15 v 
