Untitled - The Alfred Russel Wallace Website

ON THE PACIFIC COAST 335
I have never seen either leaves or flowers of the Yuca del
monte ; but, from the description given me of I it, should suppose
it a Convolvulacea, allied to the sweet potatoes (Batatas),
and the
lanceolate leaves point to the genus Aniseia.
The arborescent vegetation of the desert, although perhaps
really more scanty than the herbaceous, is from its nature more
from which not
conspicuous wherever it exists. There are points
a single tree is visible all around the horizon, but they are rare ;
generally the view takes in a few widely-scattered trees growing
in basin-shaped hollows or towards the base of slopes, where at
the wide
a certain depth there is permanent moisture throughout
interval between the anos de aguas, at which epochs the supply
is renewed. Wells dug in such sites reach water (too brackish
for drinking) at various depths, the first deposit often at only
a few feet from the surface. The moisture derived from the
garuas, scanty as it is, no doubt aids in keeping the desert plants
alive ; and we have already seen that the air is never so excessively
dry as might be supposed, but, on the contrary, sometimes
approaches complete saturation. The trees of the desert
are the Algarrobo (Prosopis horrida}, the Vichaya (Cappar is
crotonoides\ the Zapote del perro (Coticodendrum scabriduml!\
and an Apocynea with numerous slender branches, bright green
lanceolate acuminate leaves, axillary clusters of small white
flowers, and fruits, consisting of small twin drupaceous follicles,
which are slender, curved, and coated with a thin white flesh.
The Capparis and the Apocynea, although they grow to be trees
in favourable situations, as in valleys near the sea, are mere
shrubs on the desert ; and the Prosopis and Colicodendron are
low trees of very scraggy growth, their branches all bent one
way by the prevailing wind, and the trunk itself often semi-
prostrate.
Far away over the desert a tall branched Cactus begins to Inmet
with; the same species abounds on the desert -coast of
Ecuador. Farther still, near the roots of the Cordillera, the
vegetation becomes gradually more dense and varied, comprising
several other kinds of trees, and amongst them most of those
about to be mentioned as deni/ens of the valleys.
When the traveller across the despoblado comes suddenly on
one of the valleys, he passes at once from a desert to a garden,
\\ lio^e charms are enhanced by their unexpectedness. Standing
on the cliff that overlooks the Chira, about Amotape, he sees at
his feet a broad valley filled with perpetual verdure, the great
mass of which is composed of the pale green foliage
of the
Al-arrobo ; but the course of the river that winds through
it is
marked (even where the river itself is not seen) by lines or
groups of tall Coco palms, here and there diversified by the more
rigid Date palm, both growing and fruiting in the greatest