what is patches or definite layer in plants? I found these from a biology textbook that I am confused to get it. It comes from a sentence that denotes that the sclerenchyma fibre is located in patches or definite layer.
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Answer:
Lichens do not have a waxy cuticle like plants have on their leaves, nor do they have vascular tissue such as xylem and phloem to move nutrients and water around their thalli as a plant does. Everything in the lichen’s environment is absorbed into the lichen's structure. Lichens get their water and nutrients from their surrounding environment via air and rain.
The general structure of a lichen is composed of layers of fungus and alga.
Cortex
The cortex is the outer layer of the lichen thallus. These cells are thicker and more closely packed than the other fungal cells in the lichen. This layer provides some small measure of protection, as well as provides color in some species.
Algal Layer
You can usually tell what kind of alga a lichen has just by color alone. When a lichen is dry, its color is usually gray or colored like the fungal cells on the upper cortex. When a lichen is wet, those cells become transparent, and the algal cells underneath get a chance to show their vibrancy.
Green algae generally give the lichen a bright green color when wet, although there are exceptions of pigmented lichens with green algae due to the fungal partner showing its colors.
The dermal tissue system is the outer protective layer of the primary plant body (the roots, stems, leaves, flowers, fruits, and seeds).
- The epidermis is usually one cell layer thick, and its cells lack chloroplasts.
Three types of tissue systems: dermal, vascular, and ground.
- Dermal tissue is composed of epidermis and periderm.
- Epidermis is a thin cell layer that covers and protects underlying cells.
- Outer periderm is a thick layer of nonliving cork cells.