Plant Classification List
In this table the name of
the division of the plant kingdom is given first, followed in parenthesis
by its more familiar classification.
algae) grow in fresh water and in seawater. More than 7,500 species are
known. Their chloroplasts contain chlorophyll a and b, like most land
plants the green algae are usually grass-green in color, and many species
are unicellular. Most scientists believe that land plants originated from
green algal ancestors.
algae) are found mainly in ocean habitats. About 1,500 species are known.
Their chloroplasts contain chlorophyll a and c and a brown pigment called
xanthophylls, which gives these algae their dark color. Some of the brown
algae, such as the giant kelp, may grow to enormous size. Cells within the
brown algae known as seaweeds are often specialized for specific tasks.
algae and golden, or golden-brown , algae) occur in fresh water and
seawater. Over 6,00 species have been described. Like the brown algae,
their chloroplasts contain chlorophyll a and c, and other pigments give
these plants their characteristic yellowish color. The cell walls of these
algae are compose of cellulose and silicon, which give them a glasslike
appearance. Unlike other algae, the Chrysophycophyta do not store their
food in the form of starch but in the form of oil or carbohydrates.
algae) are abundant in ocean habitats, though a few species also occur in
freshwater streams and lakes. About 3,900 species are known. Their
chloroplasts contain chlorophyll a and d a red pigment called
phycocrythrin. These algae may grow at great depths in areas of the ocean
where the water is clear. Some of them accumulate calcium carbonate and
play a central role in the formation of limestone reefs.
(liverworts) are found in relatively moist habitats such as damp woods and
along streams. The number of species exceeds 8,000. Liverworts have simple
stems or no stems and may have simple leaves or flat green bodies that
resemble leaves. They are the most primitive living land plants.
(hornworts) occur in moist land habitats. There are fewer than 50 species.
Although the hornworts resemble liverworts in general form, their
reproductive structures are most similar to those of the mosses. For this
reason, botanists believe that the hornworts may represent an intermediate
stage in the evolution of the mosses from liverwort like ancestors.
(mosses) grow worldwide in habitats that range from very wet to extremely
dry. More than 24,000 species have been described. Unlike the liverworts
and hornworts, mosses often have erect stems. Their spore cases are
usually borne at the end of long stems called setae. Some are so small
that a microscope is needed to see them, but a few may be more than one
foot (30 cm) long.
(whisk ferns) are the most primitive living plants that have vascular
tissues-specialized tissues for the transport of water and food. There are
only five species. The leaves of the whisk ferns are very small and the
stems have a distinctly forked, branching pattern,. Fossils of this group
date from more than 400 million years ago.
(club mosses) are found in a wide range
of habitats worldwide. Neraly 1,200 species are known. These plants differ
from the Psilophyta in that they have transport tissues in their leaves.
They also have specialized leaves, called sporophylls, that produce the
reproductive spores. It is these sporophylls that resemble clubs and give
this group its name.
(horsetails) grow in relatively moist to very wet habitats in many parts
of the world. Today there are only about 20 species, most of which grow to
only a few feet in height. About 400 million years ago, however, there
were many more species, and some grow to be trees that were more than 50
ft. (15 meters) tall. The leaves of the horsetail rushes are very small;
most of the food production occurs in the green stems. Spores are produced
in cones that are borne at the ends of stems.
(ferns) are found in nearly all land ecosystems worldwide. They range in
size from small herbs to large trees. More than 10,000 species have been
described. Ferns differ from more primitive land plants in that they have
well-developed leaves of the tree ferns are the largest and most complex
in the plant kingdom. Ferns produce by means of spores produced in
specialized capsules on the underside of certain leaves.
(cycads) are the most primitive plants that reproduce by means of seeds.
There are about 100 species, which grow primarily in wet tropical regions.
Botanists believe that cycads evolved from fernlike ancestors more than
300 million years ago. About 280 to 70 million years ago these plants were
quite common. Pollen is produced in cones on male plants and is carried by
winds to female cones, which are on separate plants. When pollinated,
ovules develop into seeds that germinate to give rise to new plants.
(ginkgo) includes only one species, which no longer grows in the wild,
though it is cultivated worldwide as a shade tree. Its native habitat was
the deciduous forests of China. Seventy million years ago, forests of
ginkgo grew across much of Asia and North America. The ginkgo has
flattened broad leaves. Because its ovules are naked, or not surrounded by
a fruit, botanists consider the ginkgo to be a relative of the conifers.
(conifers) grow worldwide. There are about 550 species. Pollen and ovules
are exposed, or naked. The leaves of many species are needlelike, but some
species have broad leaves. Most conifers keep their leaves year-round and
are said to be evergreen, though some are deciduous and lose their leaves
in the winter.
and Ephedra) occur in diverse habitats around the world. There are 71
known species. Their structure resembles that of flowering plants.
Although their ovules are exposed like those of the conifers, they are
produced in structures that bear some resemblance to flowers. Few fossils
are known from this division, and scientist are uncertain about which
plant are the closest relatives of the Gnetophytes.
(flowering plants), also called Magnoliophyta, are the most widespread
land plants. About 400,000 species have been described, but scientist
suspect that the actual number of species may be twice that figure.
Members range in size from tiny duckweeds to giant redwoods. This division
is made up of monocotyledons and the dicotyledons. Unlike all other seed
plants, the flowering plants produce ovules that are enclosed in a fleshy
ovary. After fertilization, the ovules develop into seeds and the ovary
becomes the fruit. The fruit provides protection for the developing seed
and may also be crucial in seed dispersal. While most conifers depend on
wind for pollination, the colors and the nectar of flowers attract
insects, which then carry pollen from one flower to another.