PARTS OF PLANTS



PARTS OF PLANTS

ROOTS, STEMS, LEAVES, AND FLOWERS

What are plants? Plants are living things that are made of many cells. They are autotrophs which means they can make their own food. They do this by a chemical reaction called photosynthesis. Each part of a plant has certain jobs or functions. Leaves, stems, roots and flowers work together to help the plant perform its life functions.

LEAVES

The most numerous parts on most plants are their leaves. Leaves are considered to be a plant organ. An organ is a group of tissues that performs a specialized task. Plant leaves come in all sizes and shapes. Pine trees, for example, have needle-shaped leaves. Yellow skunk cabbage has oval leaves that can be more than one yard wide. No matter what their size or shape, leaves all perform the same function in a plant, producing food.

 Leaves have three main parts. They are the epidermis, the mesophyll, and the vascular tissue. The epidermis is the outer layers of cells covering the leaf. People also have an epidermis: their skin. The epidermis has small openings or holes called stomata (singular stoma). The stomata open and close to control when gases like carbon dioxide and oxygen enter and leave the leaf. There are usually more stomata on the underside of a leaf than on the upper side.

 

The mesophyll is the middle part of the leaf. In fact, that's what the word "mesophyll" means in Greek: "middle leaf."  The leaf can temporarily store carbon dioxide and oxygen in these spaces. These connect to the stomata on the underside of the leaf where the gases can enter and exit.

 

Between the layers of cells inside the leaf are veins that contain xylem and phloem. Xylem and phloem are vascular tissue. Xylem tissue carries water from the roots of the plant up into the leaf. Phloem tissue carries the food made during photosynthesis throughout the plant.

  

 Even though leaves may look very different, they have the same function and the same types of tissues. These different types of tissues work together in the leaf to make food for the plant.

STEMS

The stem of a plant has two important jobs. It carries substances between the plant's roots and leaves. It also provides support for the plant and holds up the leaves toward the sun. In addition, some stems provide storage for the plant. A cactus, for example, stores water in its stem. 

 

Stems can be either herbaceous or woody. Herbaceous stems are soft. Some plants that have herbaceous stems are dandelions, most flowers, and tomato plants. You can easily break these stems. In contrast, woody stems are hard and rigid. Maple trees, pine trees, and roses all have woody stems.

 

Herbaceous and woody stems consist of phloem and xylem tissue as well as many other supporting cells. However, unlike herbaceous stems, woody stems have an outer layer of material called bark, which helps protect the cells inside it. Bark covers the outer part of the stem. Bark keeps the tree from drying out, and it also protects it from injuries.

Stems anchor plants in the soil. They support the plant and help the leaves reach toward the sun. Stems transport water and nutrients from the roots to the leaves. Stems also transport sugars made in the leaves to other parts of the plant.

ROOTS

Have you ever tried to pull a dandelion plant out of the ground? It's not easy, is it? That's because most roots are good anchors. Roots have two important functions. Roots anchor a plant in the ground and absorb water and nutrients from the soil. Some plants' roots also serve as a storage area for food. Carrots and beets are two plants which store their extra food in their roots.

 

There are two types of root systems: taproot and fibrous. A taproot system consists of a long, thick main root. Smaller roots grow off the main taproot. Turnips, radishes, carrots, dandelions, and cacti have taproots. Grass, corn, and most trees have fibrous root systems. They have several main roots that branch again and again to form a tangled mass of roots and soil.

   

In the center of the root is the vascular tissue, the xylem and phloem. The water and nutrients that are absorbed from the soil quickly move into the xylem. From there, these water and nutrients are pulled upward to the plant's stems and leaves. Phloem tissue brings food made in the leaves down to the root. The root tissues may then use the food for growth or store it for future use by the plant.

FLOWERS

Flowers of plants help the plant to reproduce. The flower is the part of the plant in which seeds form. Like stems, leaves, and roots, the flowers of plants come in all shapes, sizes, and colors. The colors, sizes, and shapes are not just for show. They are important to the survival of the plant.

 

Flower parts are the petals, the pistil, the stamen, and the ovary. The petals are the parts of the flower that surround the inside parts of the flower. They are usually brightly colored to attract the insects that pollinate the plant.

The stamen is the male part of the flower. It produces a powdery material called pollen. Pollen contains male sex cells. The pistil is the female part of the flower. It contains the ovary. Inside the ovary are egg cells which can be fertilized and develop into embryos inside seeds. Wind or insects such as bees are two things that can move pollen to the pistil.

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