Plants, Algae and Fungi (Britannica Illustrated Science Library)

55 Pages·2009·27.95 MB·English

by  Michael Levy

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Plants, Algae,
and Fungi
Contents
Grain of mallow pollen, magnified 600 times,
pictured on page 1. Pollen's function is to
fertilize the female organs of the plant, a task
that is achieved with the help of bees.
Background
Page 6
From Algae
to Ferns
Page 18
Seed Plants
Page 34
Rare and
Useful Plants
Page 58
Fungi
Page 80
Green
magical. It is marvelous to understand how You may be surprised to learn why plants
an organism that cannot move learned to invest so much energy and effort into
Revolution maximize the energy that it receives from producing flowers. In this book we will
the Sun, as well as to discover the describe for you in detail, step by step, how
mechanisms that enable it to face so many fertilization takes place. Did you know that
different environmental challenges. Some pollination is aided by the wind and insects
leaves have essential adaptations, such as and that some flowers can be pollinated only
thick skin, thorns, or fleshy stalks, which by a certain species of insect? You will find
RICE CROP T here are approximately allow them to survive in very dry all this and much more in the pages of this
Rice is synonymous with 300,000 plant species in environments. Others, such as the tomato book, which includes spectacular images and
food security in much of
Asia. It is also a staple the world, and they live in a plant, form certain proteins when illustrations that give an inside view of the
food in western Africa, variety of regions, from the frozen temperatures drop in order to protect core of a tree and even show the functions of
the Caribbean, and the
tropical regions of Latin Arctic tundra to the lush tropical themselves from damage caused by freezing. its tissues and the veins of its leaves.
America. rainforests. Without plants we would
not be able to live; they have always W hat were the first plants to
been intimately linked to life on conquer the Earth like, and how
Earth. Thanks to photosynthesis, did they help convert bare rock
plants provide us with food, into soil? What happened next, and which
medicines, wood, resins, and species evolved and spread worldwide during
oxygen, among other things. the Carboniferous Period? A complete
Discovering plants' processes historical overview of plants is included in
for converting sunlight into this book, as is an explanation of the radical
carbohydrates such as sugars differences between plants, algae, and
and starches is almost fungi—the latter two of which are
now considered to be more closely
related to animals than to plants.
Although the place of plants in
the human diet is nothing new,
the search for other
beneficial uses of plants is a
more modern
development. Crops—
such as rice, corn,
wheat, rye, barley, oats,
soy, lentils, and
chickpeas—are grown
worldwide as sources of
proteins, vitamins,
minerals, and other nutrients
necessary for our bodies to
function, and they also provide
people with an important source
of income.
Background
GIANT SEQUOIA KINGDOMS OF THE QUIET LIFE 8-9
Some trees of this species are
AQUATIC PLANTS 10-11
found in central California.
CONQUEST OF LAND 12-13
ANATOMY OF A TREE 14-15
FEEDING ON LIGHT 16-17
A
ccording to scientific which were at times dry and at times amazing growth, as exemplified by the that plants grow bigger as their cells
evidence, the nearest relatives damp, the first land plants emerged. giant sequoia (Sequoiadendron multiply and expand? Many can grow 0.4
of plants are algae that lived Most had to adapt in order to prosper giganteum), which can measure 260 feet inch (1 cm) per day, and their growth can
on the shores of lagoons. in a different environment. Such (80 m) tall and 100 feet (30 m) in create enough pressure to open cracks in
Later, from these habitats, adaptation enabled them to achieve circumference at its base. Did you know asphalt.
8 BACKGROUND
Kingdoms of the Quiet Life
CONIFERS
are the most abundant plants
with seeds today. Their
R epresenting a vast array of life-forms, the plant kingdom includes approxi- reproductive structures are
called cones. Most conifers are
mately 300,000 species. Their most outstanding feature is the presen-
evergreens.
ce of chloroplasts with chlorophyll, a pigment that enables them to
transform solar energy into chemical energy. They use this energy to pro- Gymnosperma
duce their food. Plants need to attach themselves to a substrate (usually The Greek word means “naked seed.”
the ground), from which they can extract water and nutrients. This Gymnosperms are vascular plants with
exposed seeds and no flowers. Ginkgos
attachment, however, also keeps them from moving from place to place. (Ginkgophyta) and cycads (Cycadophyta) were
Algae and fungi were once included in the plant kingdom, but they are the most common plant groups in ancient SITKA SPRUCE
CYCADS GINKGOS GNETOPHYTA times. Today conifers (such as pines, larches, Picea sitchensis
now considered to be separate from plants and to belong to the kingdoms are tropical plants that look Only one species Plants with naked cypresses, and firs) are the most common
Protista and Fungi, respectively. like palm trees. Their is left in this seeds and a type. Conifers are monoicous—that is, the
reproduction is similar to group, which is vascular system same plant has both male and female sexual
MOSS that of pine trees, but they the oldest genus similar to that of organs—and their seeds are held between the
Sphagnum sp.
are dioecious (each plant has of living trees. angiosperms scales of a structure called a cone.
flowers of only one sex).
Algae Bryophytes
Fungi
are commonly considered water plants, but this is not the include mosses and worts. Mosses have rhizoids
belong to a different kingdom from that of
case. Algae have neither roots nor stalks. Because they live in rather than roots. They can also absorb water
plants. Fungi, unlike plants, do not carry out
the water (freshwater or salt water), they need no substrate. through their entire body surface. Bryophytes lack a
photosynthesis, and they store energy in the
Some are microscopic, but large algae formations can be means of surviving long periods of drought. When
form of glycogen rather than starch. Fungi are
found in the ocean. Algae are classified into families dry periods come, bryophytes enter a latent state.
heterotrophic (they get their food from other
depending on their color. Together green algae and plants Because they have no system of veins for
organisms), and they take in food by absorption.
make up the group of organisms called the “green line,” whose transporting nutrients, they can barely grow beyond
Fungi can be either parasitic or feed on dead
RED MARINE members are characterized by having chloroplasts and by 0.4 inch (1 cm) long. In order to reproduce they need organic material. Some fungi are microscopic;
ALGA storing grains of starch in the cytoplasm as a reserve. to be near liquid water.
Rhodomela sp. others are large and conspicuous. Their
bodies are composed of a mycelium, a mass
of filaments called hyphae. Some fungi also
Plants have a fruit-bearing structure. WHITE
MUSHROOM
Cycads Agaricus bisporus
The plant kingdom (Plantae) includes organisms Horsetail
whose characteristics include the presence of the Rushes Psilophyta
pigment chlorophyll to convert solar energy into Bryophytes Ginkgo
chemical energy for producing food from water and (Mosses)
Anthophyta
carbon dioxide. This ability is called autotrophy. All
or
plants, whether large or small, play an extremely Flowering
Green WHEAT
important role in providing food for all other living Algae Club Gnetophyta Conifers Plants Triticum sp.
beings. Plants cannot move from place to place, but Mosses Ferns
their gametes, spores (cells that separate from a plant
and can germinate), and seeds can move about,
SEEDLESS WITH SEEDS
especially with the help of water and wind.
WITHOUT VEINS WITH VEINS
PLANTS
FERN
Osmunda sp.
Seedless
Ferns are the most common seedless
plants today. Many are thought to Angiosperms
have originated during the Devonian
Period and reached their greatest have seeds, flowers, and fruit. They include more
splendor in the Carboniferous Period. than 250,000 species and are adapted to nearly all
Their tissues are simpler than those environments except for Antarctica. They reproduce
of plants with seeds, and their green sexually by producing flowers that later form fruits
stems have a large surface area, with seeds. Angiosperms have an efficient vascular CEREALS
FERNS SPIKE MOSS PSILOPHYTA HORSETAIL giving them a great capacity for ORCHIDS ORCHID system for transporting water (through the xylem) are monocotyledons.
are the most diverse has scalelike are extremely simple RUSHES photosynthesis. Ferns need water so have many petals; their number Cattleya trianae and food (through the phloem). Angiosperms make Their seeds have only
group of seedless leaves, some of plants; they lack have roots, stems, and that they can reproduce by means of of petals is always a multiple of up a division of the plant kingdom that includes one cotyledon
plants. Their origin which are roots and true true leaves. The leaves spores. The spores are produced in three. This makes them, along plants with bright flowers; grains, such as rice and (embryonic leaf), and
dates back to the clustered in the leaves, but they have are small and encircle spore cases called sporangia, which with cereal grains, wheat; other crops, such as cotton, tobacco, and their mature leaves
Devonian Period. form of a spike. a stalk with veins. the stems. grow on leaves called sporophylls. monocotyledons (monocots). coffee; and trees, such as oak, cherry, and chestnut. have parallel veins.
10 BACKGROUND PPLANTS, ALGAE, AND FUNGI 11
Aquatic Plants
300
THE NUMBER OF
WELL-KNOWN SPECIES
Amphibious or Wetland Plants OF WATER PLANTS
T hese plants are especially adapted for living in ponds, streams, lakes, and rivers—places where other
land plants cannot grow. Although aquatic plants belong to many different families, they have similar These species live on the edges of ponds, rivers, and swamps.
They are also found in salt marshes, which are periodically
adaptations and are therefore an example of adaptive convergence. They include submerged plants and flooded by tides or river overflows. These plants are a transition CATTAILS
floating plants; plants that may or may not be rooted at the bottom; amphibious plants, which have leaves between aquatic and land plants. Their limiting factor is the Typha sp.
availability of oxygen, so they have well-developed aerenchyma. grow in moist soil,
both above and below the water's surface; and heliophilic plants, which have only their roots underwater. around lake margins,
and in marshes in
both temperate and
tropical climates.
ARROWHEAD
Sagittaria
A Vital Role Rooted Plants with Floating Leaves LACHENALIA sagittifolia
Lachenalia Its flowers, with three white
Aquatic plants play an Such plants are often found in standing or slow-moving water. They have Floating Leaves viridiflora petals and purple stamens,
The rhizomes are fixed, the leaves grow on This plant is form during the summer.
important role in the ecosystem fixed rhizomes and petiolate leaves (leaves with a stalk that connects to a long stalks, and the leaf surface floats on attractive, with a
not only for crustaceans, insects, and stem) that float on the surface of the water. Some of the plants have the water. large number of
worms but also for fish, birds, and submerged leaves, some have floating leaves, and some have leaves outside flowers.
Upper Epidermis Aquatic plant
mammals because they are an the water, with each type having a different shape. In the case of floating
Parenchyma with especially
important source of food and shelter leaves the properties of the upper surface are different from those of the
beautiful flowers.
for these categories of animals. lower surface, which is in contact with the water. Aerenchyma
Aquatic plants also play a major role in
converting solar energy into the PARROT FEATHER TROPICAL WATER LILY Lower Air
organic materials upon which many Myriophyllum aquaticum Victoria cruciana Epidermis Conduction Chamber
This plant is native to temperate, It grows in deep, calm waters.
living things depend. subtropical, and tropical regions, and it Its leaves can measure up to 7 Bundle
is highly effective at oxygenating water. feet (2 m) across.
YELLOW FLOATING HEART
Nymphoides peltata
It produces small creased
yellow flowers all summer
long.
KNOTWEED
Polygonum sp.
This aquatic plant grows
Rooted Underwater Plants Aquatic but Modern The roots and in marshy vegetation. Pneumatophores
rhizomes under
The entire plant is submerged. The small root system SAGO PONDWEED the water are are floating roots that are involved in air
serves only to anchor the plant since the stem can directly Potamogeton densus The evolutionary history of plants began in well developed. BLADDERWORT exchange. They take oxygen from the
absorb water, carbon dioxide, and minerals. These plants This water plant can water environments. They later conquered land Utricularia vulgaris surface, and it circulates to the rest of
ahraev eo fntoe ns yfsotuenmd oinf fsluopwpionrgt —wattheer .w Tahtee rs uhbomldesr ugped t hsete pmlasnt. bdcleeep afrore-usfnlsodiow innisn sgoh fsa tlrloewams. bpyla nmtesa anrse onfo stt aru pcrtiumreitsiv seu cghro ausp r, ohootws.e Mveord. Oernn t ahqeuatic Submerged or Free Tpthlhaeenisrte sd ciceaotrm nwipviltoehrm oseumnsatll tsdhpioeax cpiedlsae.n tTto ht eehysr copaurpgoehb. aiCtbsel yritn aatlirsnao cp ealallllnuotlwasr hcaarvbeo an
contrary, they have returned to the water environment aquatic creatures. special adaptation that consists of air
by acquiring highly specialized organs and tissues. For Some underwater plants are free, without roots, but sacs that store oxygen for periods when
example, some tissues have air pockets that enable the with developed stalks and divided leaves. Other the plant will be submerged or that
plant to float. floating plants have a rosette shape and leaves speed up the plant's transpiration.
modified for floating; they have well-developed roots
HORNWORT with root caps but without absorbent hairs. The roots
Ceratophyllum sp.
This plant has an help the plant to stay balanced on top of the water.
Aerenchyma
abundance of fine
leaves that form a is always found in floating organisms. This tissue
conelike structure has an extensive system of intercellular spaces
on each stem.
through which gases are diffused.
Aerenchyma The
underwater
parts do not
have an
impermeable
outer layer, so
they can absorb
Epidermis minerals
Air and gases
Chamber EELGRASS directly from
They produce and Submerged stems have no support system Vallisneria sp. the water.
release oxygen as a because the water holds up the plant. Their limiting This oxygenating plant is
result of photosynthesis. factor is oxygen availability, so the aerenchyma found in ponds and aquariums.
helps make this substance available to the plant.
12 BACKGROUND
Conquest of Land
T he movement of plants from shallow water onto land is
associated with a series of evolutionary events. Certain changes
in the genetic makeup of plants enabled them to face the new and
extreme conditions found on the Earth's surface. Although land habitats
offered plants direct exposure to sunlight, they also presented the
problem of transpiration and the loss of water that it produces. This
difficulty had to be overcome before plants could spread over land.
Giants
Vital Changes Green Revolution Epiphytes
Trees are distinguished by their woody trunks. As a
grow on plants or on some other
Roots are among the most important Leaves are the main organs for photosynthesis in land tree grows from a tender shoot, it develops a tissue
supporting surface. Their anatomy
adaptations for plants' success in land plants. After plants appeared on land more than 440 that gives it strength, enabling it to grow over 330
includes secondary adaptations
habitats. Root systems anchor the plant in million years ago, the amount of photosynthesis taking MALE FERN feet (100 m) tall. Trees are found in the principal
that enable them to live without
the substrate and serve as a pathway for place gradually increased. This increase is believed to Dryopteris filix-mas terrestrial ecosystems.
water and mineral nutrients to enter it. be one of the reasons the concentration of carbon Tplhaenstes vnaesecdu llaiqruid being in contact with the soil.
Besides roots, the development of a cuticle dioxide in the atmosphere decreased. As a result, the water to reproduce.
(skin membrane) to cover the entire plant's Earth's average temperature also decreased.
surface was crucial. Cells in the epidermis
produce this waterproof membrane, which
50,000
helps the plant tolerate the heat generated Grasses
by sunlight and the wear and loss of water
caused by the wind. This protection is take advantage of long hours of
interrupted by pores, which allow SPECIES OF FUNGUS summer daylight to grow and
for gas exchange. LIVE ALONGSIDE reproduce. Their stalks do not have
LAND-DWELLING PLANTS. reinforcing tissues that would CHESTNUTS WALNUTS BEECHES
Castanea sp. Juglans sp. Fagus sp.
enable them to remain erect.
STEMLESS
SOW THISTLE
Sonchus acaulis
SWEET VIOLET These plants
Viola odorata lack a stem.
This plant's
spring flowers
have a pleasant
scent.
MOSS
Sphagnum sp.
Bryophytes are
the simplest of all MAPLES OAKS LINDENS
land plants. Acer sp. Quercus sp. Tilia sp.
360 Feet
(110 M)
THE HEIGHT REACHED BY SOME
SEQUOIA SEMPERVIREN TREES