An Overview of Plants

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Background

Plant Anatomy

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Overview of Plant Anatomy

Above Ground Features of a Plant

Stem – The stem is the main above ground support structure of the plant which holds the buds, leaves, flowers and fruit. The main function of the stem is to support the plant and facilitate the transportation of nutrients and water from the roots to the leaves and flowers. The stem may also store food reserves for the plant. Stems can contain few or many branches. The stem is generally located above the ground, however there are examples of stems that grow underground. An example of a plant with an underground stem is a potato.

Leaf – The leaf is a flat organ on the plant which attaches to the stem of a plant. The flat portion of the leaf is the blade, which is the main site of photosynthesis. Photosynthesis is an important process which plants and humans rely on for survival. During photosynthesis, the plant uses sunlight energy, water, and carbon dioxide to create oxygen and sugar. The sunlight contains high amounts of photons (energy from sun), which can be absorbed by chlorophyll in plant leaves. The energy from the sun is then used to power a chemical reaction inside the leaf tissue. In this chemical reaction, carbon dioxide and water are converted to oxygen and sugar. Photosynthesis gives us the oxygen that we breathe and provides sugar for plants to grow and develop! The chlorophyll pigment in leaves, gives plants their green color!

Energy (sunlight) + carbon dioxide (air) + water (soil) à oxygen (air) + sugar (plant food)

Flower – The flower is a reproductive unit found on angiosperm plants. Angiosperm plants is another way to say “flowering” plants. Flowers contain the male and female parts that are involved in the production of seeds. The parts of a flower will be discussed in the next section.

Fruit – The fruit is a structure that contains the seeds on a plant. Following pollination, the plant is able to develop seeds (baby plants). As the fruit matures, the tissue ripens (color change, fruit softens) and prepares for seeds to be deposited into the environment. Humans often eat fruits. Fruits can be very diverse in shape, color and size. Some fruits are dry fruits (peanuts) and some fruits have a fleshy skin that can be eaten. A few examples of fleshy fruits include: tomatoes, apples, and cucumber.

Below Ground Anatomy

Root – The root is a network of tissue which anchors the plant into the environment, typically the soil. The roots also play an important role as the site for nutrient and water uptake from the soil. Nutrients and water absorb in the roots and are transported to other important plant tissues. There are two major types of roots. 1) Tap Roots – have a large, central primary root. An example of a taproot is a carrot. 2) Fibrous Roots – Fibrous roots are small, highly branched root systems and are commonly found in native grass plants.

Flower Anatomy

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Overview of Flower Anatomy

Male Parts of a Flower

Stamen – The stamen is male organ on a plant that is responsible for the production of pollen. The stamen includes the anther and the filament tissue. Stamens can be different colors and play an important role in the attraction of pollinators.

Anther – The anther is the pollen producing tissue on the flower. The anther is a small sac-like structure where the pollen grains develop. When the plant enters the flowering period, the anther breaks open and spreads pollen grains to the environment. When pollinators are interacting with the flower, pollen from the anther can be transferred onto the surface of the pollinator and transferred to other plants.

Filament – The filament is the long, slender stalk that connects the anther to the base of the flower. The filament can be short or long, depending on the plant species.

Female Parts of a Flower

Carpel – The carpel is the basic female reproductive unit of the plant. The carpel includes a few important components including the stigma, style and the ovary. Carpels can also be referred to as pistils.

Stigma – The stigma is top part of the female reproductive organ which receives pollen. Pollen can be transferred from the pollinator onto the stigma. Once pollen lands on the stigma, water enters the pollen grain. The pollen grain becomes hydrated and establishes a strong connection to the stigma. The pollen grain can then form a pollen tube which transports the male cells through the female organ. When the pollen tube reaches the ovule, fertilization can occur which forms a seed (baby plant).

Style – The style is the long, slender region located between the stigma and the ovary.

Ovary – The ovary is located at the base of the female reproductive unit. The ovary houses the ovules (eggs) that are critical for the production of new seeds. Following successful pollination, the ovary will develop into the fruit. The fruit protects the developing seeds from damage. The fruit can be eaten by humans and animal, which help spread seeds into the environment!

Ovule – The ovule(s) are located inside the ovary and contain the female eggs. The eggs are fertilized by cells contained inside the pollen, which give rise to new seeds!

Other Important Features of Flowers

Sepal – the sepal forms the protective barrier surrounding the developing, unopened flower bud. When the flower blooms (opens) the sepals and petals emerge from the flower bud. The opened flower exposes the reproductive structures and allows for processes like pollination to occur.

Petal – The petal is a modified leaf which surrounds the reproductive parts of the flower. The petals can have a wide spectrum of color and play a major role in the attraction of pollinators. The petals influence the shape of the flower, which can also influence the types of pollinators that interact with a flower.

Nectaries – Regions on the flower which contain nectar. Nectar is a sugar-rich liquid produced by plants. Nectar attracts pollinators by providing a source of food. The nectaries can be found on different flower parts depending on the species of plant. Often nectaries are located on stamens, filaments, pistils (carpels), and petals.

Types of Flowers

1. Perfect Flowers – Perfect flowers contain both male and female parts on the same flower. Examples of perfect flower are prickly roses and sunflowers.
2. Imperfect Flowers – Flowers that are missing either male or female parts. This means that plants would have separate male and female flowers. An example of plants with imperfect flowers are squash, cucumbers, and Canadian holly.

Life Cycle of Plants

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Germination – After seeds are planted in their environment, they require a few important resources to germinate. The seed needs the correct temperature, oxygen, and water to germinate. Inside of the seed, the baby plant (embryo) will start to grow using the resources contained within the seed. These resources include starches, sugar and protein. As the baby plant begins to grow, it is able to break through the seed coat and start growing in the soil. The small plant has a root growing down in the soil. The cotyledons (seed leaves) push through the soil in order to seek sunlight. Once the small plant breaks through the soil and is exposed to the sunlight, it can start to produce its own energy through photosynthesis.

Seedling Phase – During the seedling phase, the plant will start to develop mature leaves. The original leaves present on the small plant when it broke through the soil were called cotyledons (also called seed leaves). The new mature leaves can often have a different appearance than the cotyledons. The mature leaf tissue will have high levels of photosynthesis occurring. This will allow the plants to grow rapidly and increase in size.

Vegetative Phase – During the vegetative stage, the plant continues to increase the production of biomass and leaves. The vegetative stage is critical to ensure plants have enough energy and nutrients before transitioning to flowering phase. During the late stages of the vegetative phase, flower buds will start to appear and emerge on the plant.

Flowering – The flowering stage in plants requires an abundance of energy and nutrients. During the flowering stage, the plants produce flower buds which eventually develop into mature flowers. When the flowers are ready for reproduction, they bloom and open up. During flowering, pollinators are able to interact with the male and female parts located on the flower.

Maturity – As the life cycle of the plant comes to an end, the plants must first go through the maturation phase. During this period, nutrients stored in the plant tissue can be moved to the seed tissue. The seeds will need this energy to undergo germination! During the maturity phase, the seeds finish development and are ready to be spread into the environment.

Task

TASK A

Questions to Discuss

1. What do we use plants for?

Food, medicine, shelter, clothing

Plants are the most important organisms on planet Earth!

2. What are important parts of plants? Why is this part of the plant important?

A wide variety of answers can be given. A few may include: stems, roots, seeds, fruits, flowers, etc. It is important to emphasize all parts of the plant have a specialized function and are critical to plant survival!

·What are some of the important stages during a plants life?
Answers could include germination, flowering, seedling stage. This lesson will explore the major events that occur during the plant life cycle.
3 What are important parts of plants involved in pollination?
Petals – attract pollinators to visit flowers
o Stigma – part of female reproductive structure where pollen is delivered to
o Anther – where pollen develops and is held until pollination occurs
4 What is photosynthesis? Why is this process important
o Photosynthesis is a process that plants perform to produce oxygen and sugar. Humans and living organisms use the oxygen to support life. The sugar produced in the plant can be used as energy by both plants and animals.

TASK B

Students will write a poem on any of the following ; plant anatomy, flower anatomy or plant life cycles and share poem with peers. Upload your poem in the assignment folder on this platform.

Learning Objectives

Understanding the anatomy and key parts of a plant
Understanding the life cycle of plants with a focus on pollination timing
Understanding the parts of a flower, which play an important role during pollination

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