Railway Science (Biology – Plant Kingdom) (Part-II)

Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction. They lack true roots, stems or leaves.
The main plant body of the bryophyte is haploid. It produces gametes, hence is called a gametophyte. The sex organs in bryophytes are multicellular.
The male sex organ is called antheridium and the female sex organ is called archegonium.

Phloem is made up of five types of cells: sieve cells, sieve tubes, companion cells, phloem fibers and the phloem parenchyma. Sieve tubes are tubular cells with perforated walls. Phloem transports food from leaves to other parts of the plant. Except phloem fibers, other phloem cells are living cells.

Sclerenchyma: It is a plant tissue providing mechanical stiffness and strength. Fibers and sclereids are the main types of sclerenchyma cells. Aerenchyma tissues help in exchange of gasses between the shoot and the root systems.
Parenchyma tissue generally stores food. In some situations, it contains chlorophyll and performs photosynthesis, and then it is called chlorenchyma,

Monocotyledon: The plants in which the seed has only one cotyledon are known as monocots. Examples- Sugarcane, banana tree, daffodils, palm.

Meristematic tissues: Constant cell division, ability to differentiate into specialized cells. These mature into permanent tissues in plants. Sclerenchyma: Supports tissue with hard woody cells in plants. Parenchyma: Living polygonal cells with large central vacuoles and intercellular spaces.

Parenchyma is a simple permanent tissue which consists of relatively unspecialised cells with thin cell walls. This tissue generally stores food. Collenchyma : It allows bending of various parts of a plant, and mechanical support. Sclerenchyma is a permanent tissue which makes the plant hard and stiff. This tissue is present in stems, around vascular bundles, in the veins of leaves, etc.

Example - Pinus, Cycas, Araucaria, Thuja, Cedrus, Picea. Angiosperms - A seed is produced by flowering plants and is enclosed within an ovary. Example - Mango, apple, banana, peach, cherry, Orange etc.
Bryophyta (Amphibians of the plant kingdom) - It lacks vascular tissues, vegetative structure. Example - Mosses, Liverworts, Hornworts.
Thallophytes - These are simple, non-vascular plants like algae, fungi, and lichens with undifferentiated structures.

Vessel is a long cylindrical tube-like structure made up of many cells called vessel members, each with lignified walls and a large central cavity. The vessel cells are also devoid of protoplasm. Angiosperms are plants that produce flowers and bear their seeds in fruits.

Parenchyma is a simple permanent tissue which consists of relatively unspecialised cells with thin cell walls. This tissue generally stores food. Collenchyma is a tissue found in plant cells that help provide support and protection. Sclerenchyma is a permanent tissue which makes the plant hard and stiff and found in plant’s stems, around vascular bundles, in the veins of leaves, etc.

Sclerenchyma - A permanent tissue which makes the plant hard and stiff. This tissue is present in stems, around vascular bundles, in the veins of leaves, etc. Humans use sclerenchyma fibers to make linen and rope.