CLASSIFYING PLANT GROUPS OCS Biology Mrs. Bonifay

PLANTS Scientists have identified more than 260,000 kinds of plants. They classify plants according to whether they have body parts such as seeds, tubes, roots, stems, and leaves. The three main groups of plants are seed plants, ferns, and mosses.

Vascular Plants Vascular plants have tube-like cells. These cells form tissue called vascular tissue. The tissue forms tubes that transport food and water through the plant. Vascular means “vessel” or “tube.” Seed plants and ferns are vascular plants..

Vascular Plants Vascular plants have well-developed leaves, stems, and roots. Because of vascular tissue, these plants can grow larger because its leaves and stems do not need to be near water. Vascular tissue is thick and provides support for a plant. This allows the plant to grow tall.

Nonvascular Plants Nonvascular plants do not have tube-like cells. Mosses are nonvascular plants. These plants are short and must have constant contact with moisture. These plants usually grow in damp, shady places on the ground and on the side of trees and rocks.

Seed Plants Seed plants are different from ferns and moss because they use seeds to reproduce. A seed is a plant part that contains a beginning plant and stored food. The beginning plant is called an embryo. The seed has a seed coat which holds in moisture. Seed plants have the most advanced vascular tissue of all plants with well-developed leaves, stems, and roots.

Seed Plants Seed plants come in many different sizes and shapes. This helps them live in many different places. Seed plants are the largest group of plants. They are divided into two groups: 1. flowering plants 2. non-flowering plants

Angiosperms Flowering seed plants are called angiosperms. A capsule, or fruit, protects the seeds of angiosperms. The fruit forms from part of the flower, which comes in many shapes and colors.

Angiosperms Angiosperms are divided into monocots and dicots. Most angiosperms are dicots, which contain two cotyledons (a structure in the seed that contains food for the developing plant). A bean is an example of a large dicot seed.

Angiosperms/Dicots When a bean is planted, the plant appears to have two leaves. If you split a bean apart, you may be able to see the two leaves in the tiny embryo. If you look at the leaves of a dicot plant, the veins are branched or netlike. This is another property of a dicot.

Angiosperms/Dicots Most flowering plants are dicots. Animals eat dicots in the form of fruits and vegetables. Other examples of dicots are oak trees, roses, sunflowers, and giant redwood trees.

Angiosperms/Monocots Monocots have only one cotyledon. When a monocot begins to grow from a seed, only one leaf appears. Also, the veins in the leaf are parallel. Monocots include grass, corn, wheat, rice, and flowers such as lilies and orchids.

Gymnosperms Non-flowering seed plants are called gymnosperms. The seeds of gymnosperms are not surrounded by fruit. The seeds are produced inside cones. For example, pine trees form on the scales of cones.

Conifers and Other Gymnosperms The major group of gymnosperms is conifers, which are cone-bearing gymnosperms. All conifers are woody shrubs or trees. Most conifers have green leaves all year. Because of this, they are called evergreens. Conifers’ leaves are shaped like needles. They do not lose water as easily as broad leaves. They can live in dry places. Other gymnosperms include the ginkgo tree, which has fan-shaped leaves. They are able to survive pollution better than other trees.

Seedless Plants There are two main groups of seedless plants: ferns and related plants, and mosses and related plants. Ferns are vascular plants, but do not have seeds. Mosses are non-vascular plants, and also do not have seeds.

Ferns Like other vascular plants, ferns have well-developed leaves, stems, and roots. The ferns’ leaves, or fronds, are usually large and flat. They are divided into leaflets that spread out from a center rib. On the underside of the fronds, you can see small dots called sori. These are clusters that contain the reproductive cells of the fern, called spores. When the spores are ripe, the sori burst open and release the spores into the air.

Ferns The rhizome is a plant part that shoots above ground and roots below ground. Fern spores that drop in a moist place, produce a a tiny plant or rhizome.

Mosses Mosses are gymnosperms. They are non-vascular plants the do not have well- developed leaves, stems, and roots. They do not have vascular tissue to transport water, so they must live in moist shady places. Mosses get water through root-like threads called rhizoids. Like ferns, mosses reproduce by spores. Mosses produce a great number of spores.

Soil and Bog Builders Mosses can grow in places where other plants cannot root because they are so tiny. Mosses grow on tree bark, rocks, and in thin soil. When moss plants die, they form humus, which is made from dead plants and animals, and is very rich and helps plants grow. A bog is wet, spongy ground that is made from rotted moss and other plant matter. Air does not reach the dead plants and the lack of oxygen keeps the plants from breaking down quickly. Over time, the plant matter becomes tightly pressed together and forms peat. Peat moss is used to enrich garden soil.