If we consider plants, based on their height, some
are too short while some are too tall to climb. Besides the height, stem
thickness, delicacy also varies.
For example–
Short plants have greenish, soft, and tender stems, while big and tall
plants or trees have a thick, strong and woody stem which are hard to
break.
Based on the growth habit, plants are broadly categorized into three groups:
Herbs, Shrubs and Trees
Herbs
Starting from the smallest, herb is a short-sized
plant with soft, green, delicate stem without the woody tissues. They
complete their life cycle within one or two seasons. Generally, they
have few branches or are branch less. These can be easily uprooted from
the soil. Herbs contain enough nutritional benefits including vitamins and minerals to make it a part of a healthy balanced diet. Tomato, wheat, paddy, grass are a few examples of herbs.
Shrubs are medium-sized, woody plants taller than herbs and shorter
than a tree. Their height usually ranges between 6 m-10 m or 20 ft–33 ft
tall. Their features include bushy, hard and woody stems with many
branches. Although stems are hard, they are flexible but not fragile.
The life-span of these plants are for many years. Rose, jasmine lemon,
tulsi, and henna are some of the common shrubs around us.
Explore more: Shrubs and their Uses
Trees
Trees are big and tall plants. They have very thick,
woody and hard stems called the trunk. This single main stem or the
trunk gives rise to many branches that bear leaves, flowers and fruits.
Some trees are branch less like coconut tree; i.e., they have only one
main stem which bears leaves, flowers, and fruits all by itself.
The life-span of the trees are very large. i.e, for several
years. Banyan, mango, neem, cashew, teak, oak are some examples of
trees.
In addition to these three categories of plants,
there are two more types which need some support to grow. They are
specifically called climbers and creepers.
Climbers
Climbers are much more advanced than creepers.
Climbers have a very thin, long and weak stem which cannot stand upright
but they can use external support to grow vertically and carry their
weight. These types of plants use special structures called tendrils to
climb. Few climbers plants names include pea plant, grapevine, sweet
gourd, money plant, jasmine, runner beans, green peas, etc.
Creepers
Creepers, as the name suggests, are plants that creep
on the ground. They have very fragile, long, thin stems that can
neither stand erect nor support all its weight. Examples include
watermelon, strawberry, pumpkin and sweet potatoes.
Learn more about Plants, its types, importance and other related topics @ BYJU’S Biology
Frequently Asked Questions
How do herbs differ from shrubs?
Herbs
are a normal plant with soft, delicate stem and are perennial, which
completes its life cycle in a year. Shrubs are taller than the herbs and
have a hard woody stem with branches.
Briefly explain the classification of plants.
There
are different varieties of plants and are mainly classified based on
certain features including growth habit, presence or absence of
specialized tissues, flowering and non-flowering plants, etc.
What is meant by Growth habit?
Growth
habit mainly refers to the appearance, shape, height, and form of
growth of a plant species. A plant’s growth habit develops from
particular genetic patterns that determine growth.
State five examples of shrubs.
The most common examples of shrubs are rose, banana, marigold, china rose, and lemon.
What are the characteristics of herbs?
The characteristics of herbs are:
They are small plants with a soft and delicate stem.
They have a green, tender, soft and delicate stem.
They have a short lifespan, which can live only for one or two seasons.
They are shorter in size and they may grow between 2 to 3 meters tall.
What are climbers?
Climbers are the plants with long, week and very thin green stem, which use external support to grow and carry their weight.
Provide a few examples of climbers.
Beans, Cucumber, Grapevine, Gourd, Jasmine, and Money Plant are a few common examples of climbers.
Provide a few examples of creepers.
Pumpkin, Passionflowers and Sweet potato are a few common examples of creepers
What are creepers?
Creepers
mainly refer to those plants which have a weak stem and are extended
horizontally along with the soil on the ground as they cannot stand
upright.
How are climbers different from creepers?
The main difference between climbers and creepers are:
Creepers spread their stem, leaves horizontally along with the soil on
the ground and also bear flowers along with the fruits on the ground.
The leaves of the creepers produce fibre-like roots which fix the plant
to the ground and provide external support to grow further.
Climbers are plants with a tender stem which grow with the help of
external support. These plants produce a twine or hook from their leaves
to climb. Some plants produce special roots that serve as the holdfasts
to climb around certain objects.
Soils are the loose mineral or organic materials found on the
earth's surface, usually (or averagely) made up of about 25% air, 25%
water, 45% mineral and 5% organic matter (humus, tiny living organisms
and sometimes plant residue).
It is the stuff that supports rooted plants in a natural
environment. There are soils practically on every land that is not
covered by water.
There are many types of soils, usually placed in classes (types) based
on their color, profile, texture, composition or structure. Each soil
type is formed differently and can be found in specific places on the
earth’s immediate surface, mid and deep under the surface. Soils on the
surface (a few millimeters deep) are usually exposed to direct climatic
and environmental factors, and are easily blown away by wind, washed
away by water or even broken down by temperature changes, human and
animal activity. There are also soils found deep down the earth, often
protected from climatic and environmental factors. (see more under soil profile)
Because soils are formed from a variety of ways and in infinite
conditions, it is hard to give a number for the types of soils we have
on earth. However, they can be grouped using the stuff that they are
made of.
For this lesson, we shall look at Sandy, Silty, Clay, Loamy, Peaty and Chalky Soils.
One important subject that many farmers and soils scientists look out
for is soil chemistry. This includes soil pH (the acidity of the soil),
nutrient level, its organic content and the chemical composition of the
minerals found in it. This is partly because different soils are used
for different things and it is important to know something about the
soils you choose. These are usually determined by the geographic
location of the soils, the types of plants growing in them, and even the
environmental factors (water and air) that the soil is exposed to.
The study of soils as naturally occurring phenomena is called pedology, and a person who studies soils (soil scientist) is called a pedologist. Importance (Functions) of soils
Soils are essential for life, in the sense that they provide the medium
for plant growth, habitat for many insects and other organisms, act as a
filtration system for surface water, carbon store and maintenance of
atmospheric gases. Let us take a closer look at each of these:
Medium for plant growth: Soils support roots and keep them upright for growth. Soils provide plants with essential minerals and nutrients. Soils provide air for gaseous exchange between roots and atmosphere. Soils protect plants from erosion and other destructive physical, biological and chemical activity. Soils hold water (moisture) and maintain adequate aeration.
Habitat for many insects and other organisms: Insects and microbes (very tiny single-cell organisms) live in the soils and depend on soils for food and air. Soils
are homes to a diverse range of organisms such as worms and termites.
They provide the needed moisture and air for the breakdown of organic
matter. (learn more about soil ecosystem) They provide a home for many organisms such as insects to lay and hatch eggs and rodents to give birth to new offsprings. A Filtration system for surface water:
After rainfall and snowmelts, water flows on the earth’s
surface to water bodies, but much of it soaks and gets infiltrated into
the ground. As it continues its way downwards through the many layers in
the ground, it is filtered from dust, chemicals and other contaminants.
This is why aquifers (underground water) are one of the purest sources
of water. Filtered water also provides plants with clean, unpolluted
water needed for growth.
Carbon store and maintenance of atmospheric gases:
Soils help regulate atmospheric Carbon dioxide ()
by acting as a carbon store. During humification (a process where soil
organisms form complex and stable organic matter) some organic matter
breakdown do not occur completely, especially in soils like peat, owing
to its high acid and water content.
On a global scale, soils contain about twice as much carbon
as the atmosphere and about three times as much as vegetation.
This results in the accumulation of organic matter in the
soil which is high in carbon content. Nitrogen, phosphorus, and many
other nutrients are stored, transformed, and cycled in the soil.
Soil Profile
If one could dig a massive trench
(hole), about 50-100ft vertically downwards into the ground, you will
notice that you would have cut through various layers of soil types. A
look at the layers from a distance gives one a cross-section view of the
ground (beneath the surface) and the kind of soils and rocks it is made
up of.
This cross-section view is called a Soil Profile. The profile is made up of layers, running parallel to the surface, called Soil Horizons.
Each horizon may be slightly or very different from the other
above or below it. Each horizon tells a story about the makeup, age,
texture and characteristics of that layer.
Most soils have three major horizons. These are A Horizon, B Horizon and C Horizon. Aside from these three, there are also the O, E and R horizons. How are they different?
The O-Horizon:
The O horizon is very common in many surfaces with lots of
vegetative cover. It is the layer made up of organic materials such as
dead leaves and surface organisms, twigs and fallen trees. It has about
20% organic matter. It is possible to see
various levels of decomposition occurring here (minimal, moderately,
highly and completely decomposed organic matter). This horizon is often
black or dark brown in color, because of its organic content. It is the
layer in which the roots of small grass are found.
The A-Horizon:
The A horizon may be seen in the absence of the O horizon,
usually known as the topsoil. It is the top layer soils for many
grasslands and agricultural lands. Typically, they are made of sand,
silt and clay with high amounts of organic matter. This layer is most
vulnerable to wind and water erosion. It is also known as the root zone.
The E-Horizon:
The E horizon is usually lighter in color, often below the O
and A horizons. It is often rich in nutrients that are leached from the
top A and O horizons. It has a lower clay content and is common in
forested lands or areas with high quality O and A horizons.
The B-Horizon:
The B-horizon has some similarities with the E-horizon. This
horizon is formed below the O, A and E horizons and may contain high
concentrations of silicate clay, iron, aluminum and carbonates. It is
also called the illuviation zone because of the accumulation of minerals. It is the layer in which the roots of big trees end.
The C-Horizon:
The C horizon lacks all the properties of the layers above
it. It is mainly made up of broken bedrock and no organic material. It
has cemented sediment and geologic material. There is little activity
here although additions and losses of soluble materials may occur. The C
horizon is also known as saprolite.
The R-Horizon:
The R horizon is bedrock, material, compacted and cemented by
the weight of the overlying horizons. It is the unweathered parent
material. Rock types found here include granite, basalt and limestone. Types of soil
Sandy Soils Sandy soils are free
draining, with the largest, but fine and hard particles. It has a gritty
feel. It does not bind very well. It is poor in holding water and
easily warms up in the spring season. Sandy soils are very low in
nutrients, as they are usually washed away. Its degree of aeration
depends on the sizes of the particles, which vary a lot in size.
It is usually formed from the weathering or disintegration of bedrock such as shale, limestone, granite and quartz.
Silty Soils
This kind is finer, smoother in texture and holds water better than
sandy soils. It also holds up nutrients and makes it better for crop
cultivation. Silty soils are heavier than sandy soils, and almost midway
between the properties of sandy and clay soils.
It is formed when fine sediments (dust, organic matter and debris) are
carried by water or ice and deposited. When silt is deposited and
cemented with time, it forms siltstone. Silt particles are so small and
not easily seen by the eyes. It leaves a bit of residue after you touch
them.
Clay
The particles that make up clay are the finest and they bind very well.
It has very little air spaces. Clay very sticky when wet, and can be
molded into any shape and form. When they dry, they are rock hard. Clay
soils do not drain very well. Clay is believed to form in places where
the rock is in contact with water, air or steam. Example, sediments on
sea or lake bottoms may become clay soils with time.
Loamy
This soil is a mixture of sand, clay and silt particles and has the
ability to retain water. It is high in calcium, aeration and ideal for
most crops and vegetables. It is the soil all farmers dream of, as it is
full of nutrients from decomposed organic material. It is soft and easy
to cultivate.Peaty
Peaty soils are acidic and as a result, does not support
decomposition very well. It is dark in color, rich in organic material,
although contains less nutrients than loamy soils. It retains water very
well.
Chalky
Chalky soils are alkaline with a pH of about 7.5. It is
not acidic and often stony with chalk or limestone bedrock. It is free
draining because of its coarse and stony nature. Not the best for crops
to grow in as they lack manganese and iron. What is soil conservation?
From the pages earlier, we learned about the role of soils and how
essential they are for life on earth. Unfortunately, soils are under
threat in many ways, from excessive farming practices, use of chemicals
during agricultural practices, water, land and air pollution, erosion
and so on. These upset the natural function of soils and affect many
ecosystems that depend on it for survival.
This is why soil conservation is very important. It is the actions we
can take, or things we can apply to our use of soils and lands to ensure
their sustained health and quality.
Here are a few:
Planting vegetative cover:
The root systems of vegetative cover hold soils in place and prevent
wind and water erosion. It also ensures its supply of organic matter
from dead leaves and dropping of animals waste. The vegetative cover
also shelters the soils from excessive heat from the sun. It helps to
reduce evaporation and retain soil moisture, needed for the breakdown of
organic matter.
Careful waste disposal and management:
When we recycle more and compost our food waste, we reduce the amount of
contaminants that we introduce to soils. We also give back to the land,
rich humus from composts that we do. This is why we need to manage our
waste well to ensure that our soils are alive and healthy.
Farming practices:
No-till farming, terrace and contour farming are all great ways to
conserve soil quality. Regarding no-tilling, crops are allowed to stay
after the harvest season, to shed off naturally, thereby holding the
soil together and sheltering the soils from wind and water action.
Terrace and contour farms take into account the slope of the land to
reduce run-off after the rains. In many places, windbreaks, usually
composed of trees or shrubs planted along specific distances in farms
are effective ways of controlling wind erosion.
Soil Ecosystems
There are some really cool ecosystems that many of us forget to
mention when we talk about ecosystems. If you could turn yourself into a
small soil burrowing insect, you would be amazed by the life and
interactions that go on under the surface of soils. All the members of
this wonderful ecosystem are so tiny that it is hard for the eyes to
see.
Look at this illustration below. It shows a basic food web in the soils. The arrow shows the direction of energy flow.
In the soils, there are roots of plants. That is a "biotic" factor. The
roots depend on nutrients, moisture, air and temperature (abiotic
factors) to survive. The roots also depend on fungi and bacteria to
protect the roots from harmful bacteria attaching to it. There are also
tiny organic matter existing there.
Nutrients and air are provided by tiny animals such as arthropods
shredders, (weevils, millipedes, termites and worms) that dig and turn
the soils as they feed on fungi and bacteria on dead plant material. The
waste (droppings) of these arthropods provide the chemicals needed for
the decomposition of other organic material.
Birds and small animals like moles also depend on mites, weevils and
insect-eggs for food. Together, they all depend on moisture and air to
live in the soils.
It is important that all the members of this ecosystem, together with
their abiotic factors are active to ensure the survival of the
ecosystem.
Factors affecting soil formation
Soils form from the interplay of five main factors namely Parent material, Time, Climate, Relief and Organisms. Parent material:
This refers to the mineral material or organic material from which the
soil is formed. Soils will carry the characteristics of its parent
material such as color, texture, structure, mineral composition and so
on. For example, if soils are formed from an area with large rocks
(parent rocks) of red sandstone, the soils will also be red in color and
have the same feel as its parent material.
Time:
Soils can take many years to form. Younger soils have some
characteristics from their parent material, but as they age, the
addition of organic matter, exposure to moisture and other environmental
factors may change its features. With time, they settle and are buried
deeper below the surface, taking time to transform. Eventually, they may
change from one soil type to another.
Climate:
This is probably the most important factor that can shape the formation
of soils. Two important climatic components, temperature and
precipitation are key. They determine how quickly weathering will be,
and what kind of organic materials may be available on and inside of the
soils. Moisture determines the chemical and biological reactions that
will occur as the soils are formed. A warmer climate with more rainfall
means more vegetative cover and more animal action. It also means more
runoff, more percolation and more water erosion. They all help to
determine the kind of soils in an area.
Relief:
This refers to the landscape position and the slopes it has. Steep, long
slopes mean water will run down faster and potentially erode the
surfaces of slopes. The effect will be poor soils on the slopes, and
richer deposits at the foot of the slopes. Also, slopes may be exposed
to more direct sunlight, which may dry out soil moisture and render it
less fertile.
Organisms:
The source and richness of organic matter are down to the living things
(plants and animals) that live on and in the soils. Plants, in
particular, provide lots of vegetative residues that are added to soils.
Their roots also hold the soils and protect them from wind and water
erosion. They shelter the soils from the sun and other environmental
conditions, helping the soils to retain the needed moisture for chemical
and biological reactions. Fungi, bacteria, insects, earthworms, and
burrowing animals help with soil aeration. Worms help break down organic
matter and aid decomposition. Animal droppings, dead insects and
animals result in additional decaying organic matter. Microorganisms
also help with mineral and nutrient cycling and chemical reactions. GO TO LINK:https://www.eschooltoday.com/soils/factors-that-affect-soil-formation.html AND LEARN MORE
Soils support roots and keep them upright for growth.
)
by acting as a carbon store. During humification (a process where soil
organisms form complex and stable organic matter) some organic matter
breakdown do not occur completely, especially in soils like peat, owing
to its high acid and water content. 
. 
Farming practices: 
