Download are an example of a nonvascular plant. Flowers an

If you were put into a garden full of various plants and then
given the job to classify each one, how would you be able to do it?
Where would you start?
Most people already know that organisms are classified into
groups. Animals and plants are not the same. Dogs and bees are
different. A person and a tomato cannot be brothers. Living beings
have different characteristics that set them apart from one another.
This is the same within any group of organisms. They can be further
split into smaller groups based on physical, behavioral, or a number of
different types of characteristics. Plants are no different. Plants are as
diverse as animals, and we use the differences to classify them into
groups and subgroups.
A plant is any organism that can be classified into the Plant
Kingdom. And each member of this kingdom is grouped further based
on features such as root depth, stem thickness, and fruit production. To
find where a plant belongs, observations and simple questions lead the
way. This article is going to focus on four questions that can allow you
to figure out where to classify many plants.
How does the plant absorb and circulate food?
A basic grouping of plants is based on how food is absorbed
and circulated. A plant will either be classified as being vascular or
nonvascular. Vascular plants have a well-developed system for
transporting water and food; therefore, they have true roots, stems, and
leaves. Nonvascular plants do not have a well-developed system for
transporting water and food; therefore, do not have true roots, stems, or
leaves.
Vascular plants are the largest group in the Plant Kingdom.
These plants have tube-like structures that provide support and help
circulate water and food throughout the plant. Xylem transport water
and minerals from the roots to the rest of the plant. Phloem transport
food from the leaves to the rest of the plant. Examples include trees
and many shrubs with woody stems that grow very tall and grasses,
dandelions, and tomato plants with soft herbaceous stems.
Dandelions
are an
example of
a vascular
plant.
Nonvascular plants are much different and there are far less
plants that fit into this group. Because they do not have root systems,
nonvascular plants have other ways of transporting water and food.
They must obtain nutrients directly from the environment and distribute
it from cell to cell throughout the plant. This usually results in these
plants being very small in size. Examples include mosses, liverworts,
and hornworts.
Mosses
(hanging from
the trees) are
an example of
a nonvascular
plant.
How does the plant reproduce and make new plants?
There are two classifications of plants based on how they
reproduce: seed-producing plants and spore-producing plants.
Seed-producing plants are what we call plants that reproduce through
seeds. Seed plants make their own seeds. Seeds contain the plant
embryo (the beginnings of roots, stems, and leaves) and stored food
(cotyledons) and are surrounded by a seed coat. From those seeds, new
plants grow.
Flowers and
pine trees are
both seedproducing
plants.
Spore-producing plants are plants that produce spores for
reproduction instead of seeds. Spores are much smaller than
seeds. Almost all flowerless plants produce spores. Examples include
mosses and ferns.
How does the plant produce seeds?
Seed-producing plants are further split into two groups based
upon how seeds are produced: flowering plants and cone-bearing plants.
Flowering plants differ from cone-bearing plants because they grow
their seeds inside an ovary, which is embedded in a flower. The flower
then becomes a fruit containing the seeds. Flowering plants are also
known as angiosperms. Examples include most trees, shrubs, vines,
flowers, fruits, vegetables, and legumes.
Cone-bearing plants are different because they never have
flowers but produce seeds in cones. These plants are also called
conifers or gymnosperms. Most conifers are evergreen with needle-like
leaves. Examples include pine, spruce, juniper, redwood, and cedar
trees.
Gymnosperms
like pine trees
produce seeds
without flowers,
but angiosperms
produce seeds
from flowers.
And the final question, what kind of leaves does the plant have?
Leaves of a plant give us a lot of clues about the plant’s seeds.
The more storage a seed has for food, the more leaves it will have.
A seed with one food storage area is called a monocotyledon, or
monocot. Flowers of monocots have either three petals or multiples of
three. The leaves of monocots are long and slender with veins that are
parallel to each other. The vascular tube structures are usually scattered
randomly throughout the stem. Examples include grass, corn, rice,
lilies, and tulips.
A seed with two food storage areas is called a dicotyledon, or
dicot. Flowers of dicots have either four or five petals or multiples of
these numbers. The leaves are usually wide with branching veins. The
vascular tube structures are arranged in circular bundles. Examples
include roses, dandelions, maple, and oak trees.
The oak tree is an example of a
dicot, and the grass
surrounding it is an example of
a monocot.
I’m a Survivor/Not Gonna Give Up…
What a Plant Needs
Plants are organisms that perform certain processes necessary
for survival. A process is something inside of the plant that, usually,
happens on a cellular level (in the cells of a plant). Plants cannot live
without these three things happening inside of them. The
vital/necessary processes are photosynthesis, respiration, and
transpiration.
Plants are autotrophs. This means that they are organisms that
make their own food. Their food is a simple sugar and the process by
which they make this sugar is called photosynthesis. Chloroplasts,
found in the cells of the leaf, contain chlorophyll, a green pigment that
absorbs light energy. During this process, plants use carbon dioxide
gas from the air (taken in through openings, or pores, in the leaf called
stomata) and water (taken in through the roots) to make sugar (food) in
the leaves.
During the process of photosynthesis, oxygen is also
produced. The oxygen is released into the air through the
stomata. Photosynthesis is the process that provides the oxygen in the
atmosphere that most living organisms need. The food (sugar) created
through the process of photosynthesis is used to provide energy needed
by the plants to perform life functions.
Sun
Light
Water
Oxygen
Chlorophyll traps
light energy to
make food.
Carbon
Dioxide
Sugar
To obtain the energy from the food it produces, plants must
break down the sugar in the cells throughout the plant in a process
called respiration. In this process, oxygen from the air (taken in
through the stomata) combines with the sugar, which is then broken
down into carbon dioxide and water. During this process, energy is
released. This energy can now be used by the plant to perform life
functions. The carbon dioxide and water that are formed are then given
off through the stomata in the leaves.
Some of the water taken in through the roots of plants is used
in the process of photosynthesis. However, plants lose most of the
water through the leaves. This process is called transpiration. Without
a way to control transpiration, plants would wither up and
die. Fortunately, plants are able to slow down transpiration. Guard
cells, mostly on the underside of the leaf, open and close the
stomata. When the stomata are closed, water cannot escape from the
leaf.
Just like every other organism on Planet Earth, plants must
have food. Photosynthesis is the process by which the food is made
from sunlight and water. The food is then broken down by the process
of respiration. As a part of these processes, water is lost because of
transpiration, but the plant can regulate this water loss by slowing down
transpiration.
All organisms need food to live, but they also need to respond
to changes in the environment. Habitats for plants, animals, and insects
are always changing. They change because of weather, season
progression, introduction of new species, human intervention, or any
number of reasons. When this happens, organisms must respond in
order to survive and be able to reproduce.
Plants are no different. They need to respond to
environmental stimuli (changes or interactions from other organisms).
The response depends upon the stimulus. Sometimes seeds do not have
the right conditions to grow. Sunlight can be blocked from a growing
plant. The direction a plant grows can change because of movement of
soil. A water source can change or move. Animals may invade a
plant’s habitat and interact directly with a plant. All of these stimuli
trigger a behavioral reaction in most plants.
Under certain conditions, when a mature plant or seed
becomes or remains inactive because of growing conditions, it is said to
be dormant. Dormancy is a period of time when the growth or activity
of a plant or seed stops due to changes in temperature or amount of
water. Dormancy allows various species to survive in particular
environments. It helps to ensure that seeds will germinate when
conditions are favorable for survival of the small seedlings. For
example, leaves fall from trees prior to the conditions of winter and the
leaf buds do not open again until conditions are favorable in the spring.
This is a bag of corn. Corn is
a plant seed. Corn seed
bought in a store is an
example of a seed in
dormancy.
Plants also have behavioral response mechanisms once the
seed does start growing, During the other types of environmental
stimuli, plants can respond by moving (during growth) their stems,
roots, or leaves toward or away from the stimulus. This response, or
behavior, is called a tropism. There are several types of plant tropisms.
Phototropism is the way a plant grows or moves in response to light. A
plant will grow in the direction of a light source. Often a plant will
grow diagonally or sideways to follow the direction of sunlight.
The satellite dish is
casting a shadow
and blocking the sun
from this plant. The
plant responds by
growing in the
direction of the
sunlight.
Gravitropism is how a plant grows or moves in response to
gravity. This can also be called geotropism. Roots will always grow in
the direction of gravity (down), and stems will always grow in the
opposite direction. If a plant or tree is growing on a hill, it will grow in
a slanted direction to the ground around it because it will always grow
in a directional relationship to gravity and not the ground. Another
example is that if you turn a plant upside down, the stem and leaves
will start to grow upwards around the pot. (continued on next page)
This tree is on a hill. Because of
gravitropism, it grows in a direction diagonal
to the ground.
This is a very popular as-seen-onTV product that uses gravitropism
to allow people to grow
strawberries without a yard.
Hydrotropism is what happens when a plant grows or moves
in response to water sources. Roots will follow water. The roots go
where the water is with hydrotropism, as the leaves and stem follow
sunlight with phototropism. If a water source dries up or moves, the
roots grow out in search of water. When a water source is found, the
roots will grow in that direction.
Thigmotropism is plant’s response to touch. Some plants
have a reaction when touched or touching an object. A rare example
being flowers that closed when touched. A very common
thigmotropism, one so common it could be in your front yard, is
something called morning glories. Morning glories grow a lot like a
vine, and the stem has structures called tentacles. When these tentacles
are not touching anything, they grow in a spiral shape. As soon as the
tentacles touch something, they began to wrap themselves around the
object as they grow. This response is a thigmotropism.
To the left you see morning glories.
Below you can see how the tentacles of
the morning glories have wrapped
themselves around the stems of other
plants. This is a thigmotropism.
Roots are another vital structure in plants that allow them to
live and reproduce. They help anchor the plant in the ground. They
also absorb water and nutrients from the soil and store extra food for
the plants. The more surface area on the root that is available, the more
water and nutrients it can absorb, and root hairs help to increase this
surface area.
There are two types of roots: fibrous roots and taproots.
Fibrous roots consist of several main roots that branch off to form a
mass of roots. Examples are grass, corn, and some trees. Taproots
consist of one large, main root with smaller roots branching off.
Examples are carrots, dandelions, or cacti.
Seeds can also be a survival structure that has developed in
plants. Seeds, in of themselves, are a way for plants to reproduce, but
there other specific characteristics that some seeds have that help plants
to live and thrive. Some seeds have special structures that allow them
to be dispersed by wind, water, or animals. The seeds coat helps
protect the embryo from injury and also from drying out.
Dormancy and tropisms allow plants to adapt to changes in
their environment. When they adapt, they have a much better chance of
surviving and reproducing.
Structured to Live
Many flowering plants also have unique structures that aid in
their defense and survival. Plants have structures for defense that
protect them from threats and without these defenses the plant might
die. One example of natural defense that plants have developed is the
presence of thorns that can defend the plant from being eaten by some
animals. Other examples can be fruits and leaves with poisons so that
they are not eaten by animals or the ability to close its leaves when
touched (thigmotropism).
Holly tree leaves have
small thorns on them,
and this is a defense
mechanism for this
type of plant.
Plants also have structures that allow them to survive in their
habitats when the conditions are not suitable. An example that you
probably did not realize was a survival structure is leaves. Leaves
function as the site of photosynthesis, respiration, and transpiration in
plants. Another well-known part of a plant that serves to aid in survival
is the stem.
Stems support the plant and hold the leaves up to the light.
They also function as food storage sites. The xylem in the stems
transports water from the roots to the leaves and other plant parts. The
phloem in the stems transport food made in the leaves to growing parts
of the plant.
Stems are easier
to see on flowers
and small plants,
but not everyone
knows that the
stem of a tree is
the trunk.
Without the structures mentioned, plants would have trouble
continuing to live in certain areas. These structures developed to help
allow plants to live in their environments and adapt will to changes in
weather, soil nutrients, and water/sunlight sources.
The Cycle of Life
All flowering plants have similar life cycles, and each stage of
the life cycle is distinct from the others and vital to survival of the
plants. When seeds are dispersed from the parent plant, they can either
lay dormant or they can begin to grow immediately given the right
conditions. This early stage of seed growth is called germination. The
roots begin to grow down, while the stem and leaves grow up. Over
time the seed grows into a mature plant with the structures necessary to
produce more plants. The growth and maturity of a plant is called plant
development. It is only when the plant reaches full maturity that it can
reproduce.
The Life Cycle of Flowering
Plants:
1. Germination
2. Plant
Development
3. Pollination
4. Fertilization
5. Seed Production
When pollen, which is produced in the stamen of a flower,
transfers from stamen to pistil (pollination) and then enters the ovule,
which is located in the ovary of a flower, fertilization occurs. The next
step is seed production. Once the ovule is fertilized it develops into a
seed. A fruit (fleshy, pod, or shell) then develops to protect the seed.
Seeds are structures that contain the young plant surrounded by a
protective covering. The life cycle then begins again once that seed
germinates and begins to grow.