LESSON 3 – CLASSIFICATION OF PLANTS
The plant kingdom is divided into two major groups:
1) The Bryophytes or the non-vascular plants and
2) The Tracheopytes or the vascular plants
The Bryopytes (Non-Vascular Plants)
These are plants that lack vascular tissues. They don’t possess true roots, stems, and leaves. They are plants that cannot transport water and nutrients through out the plant efficiently because they lack tissues.
Bryophytes live in moist and shady surroundings. Most of them can be found attached to other plants, logs, and even in rocks. They also live on land. The root-like structure of bryophytes is called rhizoids.
Rhizoids absorb nutrients from water on their habitat. It also serves as anchorage of plants to the ground.
Bryophytes are divided into three groups: the mosses, hornworts and liverworts.
Though bryophytes are small in size, they have an important role.
They prevent soil erosion because they serve as the carpet on the ground. They also serve as mulching.
They increase the holding capacity of the soil. As they are mixed into the soil, bryophytes increase the organic matter in it.
The Tracheophytes (Vascular Plants)
Tracheophytes are vascular plants, they have tube-like structures that transport water, food, and other nutrients to the other parts of the plant. Vascular plants have true roots, leaves, stems, and a reproductive organ.
A tracheophyte contains two transporting tissues:
1) The Xylem – transports water and nutrients from the roots to the leaves of the plant
2) The Phloem – transports the water and nutrients from the leaves to the other part of the plant.
There are 2 classification of vascular plants based on how they reproduce, these are the spore producer and seed producer.
A) SPORE PRODUCER: FERNS
Plants that are spore producers are also called seedless vascular plants.
Fern – is the most common plant with these characteristics.
- They grow anywhere.
- Some are edible, some are not
- They produce spores.
- Spores – are dotted like seen underside of the leaves.
- Each leaf of a fern is called frond.
- The group of spores that form a brown spot is called the sori.
- Ferns have roots, stems and leaves.
- They reproduce sexually & asexually.
B) SEED PRODUCER
- Most plants with vascular tissues produce seed.
- These plants are classified into 2 groups:
1) The Gymnosperms or the non-flowering plants
2) The Angiosperms or the flowering plants.
B1) Gymnosperm
Ø are plants that do not bear flowers.
Ø They live in cold places.
Ø There are 700 species
Ø They are naked seeds. These seeds are visible because they develop on the female cone and not inside the fruit.
Example are:
Eg.1) Conifers
- are plants that produce seeds in cones.
- Their leaves are needle-like.
- Conifers have both the female and male cones that have important roles in the reproductive cycle. The female cone is larger than the male cone.
- Example: Pine tree
Eg.2 ) Cypress
Eg.3) Cycads
B2) Angiosperm
Ø Angiosperms belong to the phylum angiospermophyta which is derived from the Greek word “angi” which means small container and “sperma” meaning seed and “phyton” – a plant.
Ø Flowering plants including trees, herbs, grasses and aquatic plants differ in the structure of their stems, leaves and flowers.
Ø Stems differ in nature and size. Some stems are rough while others are smooth. The leaves may either be alternate, opposite or radial. It may be netted or parallel. Its flower maybe complete or incomplete.
Ø Flowers have different kinds and they vary in shapes, sizes, and colors. They are important in plant production. The pistil (female organ) and the stamen (male organ) are the most important parts of a flower. They are involved in the sexual reproduction of a plant.
Ø The flower is said to be complete when both male and female reproductive organ is present. It is incomplete when one of the male or female parts is absent.
Ø Flowers can also be perfect or imperfect. Perfect flowers are flowers having the important parts even though some other parts of it is not present. If the part which is not present is found necessary, it is an imperfect flower.
Ø Angioperms are also classified according to the number of cotyledon or seed leaf present in the seed, the dicotyledon and monocotyledon.
Ø The dicotyledon leaves have netted venations while monocotyledon is narrow and parallel. The arrangement of their vascular tissue is not the same too. The dicot is in ring form while monocot are scattered. The roots of dicots have taproots unlike the monocot that are fibrous.
