of the root from aboveground. Prop roots are root
clusters that emerge from the trunk well above
ground. Surface roots, as the name implies, wind
conspicuously over the surface of the forest floor.- Bark is variable among tree species. It may be light
or dark, smooth or ridged, depending upon species.
There is no generalized pattern for bark color or
texture. - Many epiphytic plants grow on branches and bark,
often densely, including various lichens, orchids,
ferns, and others. - Other plants, many vine- like, of many kinds
(stranglers, lianas) are common and often abundant. - The litter layer is often thin, as leaf decomposition
rates are high. - Soil is usually reddish but may be of some other color
and is typically acidic, often high in clay content.
There is much variability in soil characteristics.
Some tropical soils are sandy, and some are rich in
nutrients, but many are thin and poor in nutrient
content. In general, floodplain soils are rich in
nutrients, and upland soils are nutrient- poor.
Identifying Neotropical Plants (or Not)
The plants of the Neotropics are not well catalogued,
the way birds, butterflies, and mammals are. Because
of the remarkable profusion of Neotropical plants,
there are no real species- by- species field guides with
which to match up a plant with a species name. The
vast majority of students of Neotropical biology will
not find it possible to accurately identify most plants
they see to the level of species. There are just too many
look- alike species, and the ranges of many species
are not precisely known. Thus species identification
must be left to taxonomic experts. With the help of
identification guides it is possible to identify many
Neotropical plants to the level of family, and many
of those to the level of genus. Using combinations of
characteristics such as leaf shape (palmate, pinnate),
compound vs. simple leaves, opposite vs. alternate
leaves, presence or absence of tendrils, presence or
absence of spines, smooth or serrate leaf edges, fruit
and/or flower characteristics, and even, in many
cases, odor and taste, you can master the flora at least
to the level of family. Hopefully, there will be more
identification guides published on the plants of various
Neotropical regions.Typical Tropical Trees
Though there are more individual tree species in the
tropics than anywhere else (something about which we
will have much more to say), many trees are sufficiently
similar in appearance that we can meaningfully
describe a “typical” tropical tree. The world’s tropical
forests have converged in many of the basic structural
characteristics. First and foremost, tropical trees are
broad- leaved and most remain in leaf throughout the
ye ar.Stature
Tropical rain forests are known for having huge trees.
Old engravings depict trees of stunning size with up to a
dozen people holding hands around the circumference
of the trunk. These giants still exist in some uncut
forests, but in most places you are apt to visit, the trees,
though large and surely impressive, are not as huge
because of past disturbances to the forest. Tropical tree
branches do not radiate from the trunk until almost
canopy level, thus enhancing the appearance of height
(plate 3- 3). The tallest tropical trees are found in
lowland rain forests, and these range from 25 to 45 m
(approx. 80– 150 ft) in height; the majority are about
25– 30 m (80– 100 ft) tall. Tropical trees occasionally
exceed heights of 45 m (150 ft), and some emergents
do top 60 m (200 ft) and may occasionally approach
90 m (300 ft), though such heights are uncommon.
Some temperate- zone forests have equally tall orPlate 3- 3. Typical tropical trees are tall and straight, with major
branches emerging near canopy level and making the tree
shape somewhat like that of an umbrella (which you often
need in rain forest). Photo by John Kricher.chapter 3 rain forest: the realm of the plants 41