March 26th 2023

LESSON THREE

They are mostly green in colour due to the possession of chlorophyll for photosynthesis.
They are non-motile multicellular organisms.

The kingdom has a number of divisions, these are

They are simple, aquatic green plants.
They have a thread-like (filamentous) or flat (thallus) bodies.
They do not have true leaves, roots, or stems.
Some are green (eg green algae) while others contains colored pigments (eg brown and red algae).
They are mainly seaweeds although some green algae are found in fresh water.
Some reproduce asexually by cell division, fragmentation, or spores, others reproduce sexually by producing gametes.
They show alternation of generation.

Examples: Spirogyra, red algae, brown algae etc.

They do not possess roots, stems, and leaves.
They are non vascular in nature.
They grow in a damp or wet places.
They reproduce sexually be producing motile male gamete known as spermatozoa (singular; spermatozoon) or sperms and non motile female gamete known as Ova (singular; ovum) or eggs.
They also shows alternation of generation.

Examples: Moss and liverworts

They are vascular plants.

They are land plants having true leaves, stems and leaves.
Their stems is called Rhizome.
Their leaves is called fronds which grown upward above the ground coiled when young and unroll when they grow with the matured fronds bearing spores on the underside.
They shows alternation of generation with the sporophyte and gametophyte leads separate existence.
They are called the fern family.

They are seed producing plants.
The seed contains embryo which develops from a fertilized egg of a very small gametophyte which us completely dependent on the sporophyte.
The fertilisation is brought about by pollination, followed by the growth of the pollen tube which carries the male gamete to the egg. Hence, water is not needed in this process.
They have well developed roots, stems and leaves.
The seed plants are divided into gymnosperms and angiosperms.

Gymnosperms

They are plants with naked seeds.
They do not hear flower.
They are tress or shrubs mostly evergreen.
They possess needle-like leaves, although a few have scale-like leaves or broad leaves.
The seeds are borne on a special structure called Cones.
Some (especially the conifers) dominate the world's temperate regions and produces soft wood which is used in making timber and wood pulp (paper making) and also yield resins and turpentine.

Examples: gingkos, cycads and conifers.

Angiosperms

They are flowering plants.
They form the largest group of the plant kingdom.
They have an abundance of water-conducting vessels.
They bear seeds which are protected within fruits.
The fruit is developed from the ovaries of flowers (female reproductive organ of the angiosperms).
They are grouped into Monocotyledons and Dicotyledons

Monocotyledons

Examples: Mainly cereals (eg rice), oil palm, etc

Dicotyledons

Examples: Mainly legumes (eg cowpea), yam, pawpaw etc

Possession of shoot and root systems.
The roots, stems and leaves are the vegetative part which contains the dermal, vascular bundles (xylem and phloem) to transport food, water and minerals throughout the plant, and the ground tissues other than the dermal and the vascular tissue.
The flowers which give rise to fruits and seeds are the reproductive part.

This post first appeared on Biology, please read the originial post: here