Table of Contents
Meaning of Tissues
Plants tissues can be divided into three types: meristematic tissues, permanent tissues, and protective tissues.
Meristematic tissues are responsible for the growth and development of plants. They are located at the tips of stems and roots, and in the buds of plants. Permanent tissues are responsible for the structural support and function of plants. They are found in the stems, leaves, and roots of plants. Protective tissues provide a barrier between the plant and the environment. They are found in the bark of trees and the leaves of plants.
There are four main types of tissue in plants: dermal, ground, vascular, and reproductive.
Dermal tissue is the tissue that covers the outside of the plant. It helps protect the plant from the environment and can produce toxins to deter predators. Ground tissue is the tissue that makes up the bulk of the plant. It includes the cells that are responsible for photosynthesis, nutrient storage, and water uptake. Vascular tissue is the tissue that transports water and nutrients throughout the plant. It includes the xylem and phloem which carry water and dissolved minerals from the roots to the leaves and fruits, respectively. Reproductive tissue is the tissue that produces the plant’s seeds or flowers.
Parenchyma
cells are the most common type of cell in the plant body. They are found in all the tissues of the plant, but are most abundant in the leaves and the fruits. Parenchyma cells are simple, spindle-shaped cells with a large central vacuole. The vacuole is a membrane-bound organelle that stores water and other substances.
The cytoplasm of a parenchyma cell contains numerous small organelles, including the chloroplasts. Chloroplasts are organelles that contain the green pigment chlorophyll. Chloroplasts are used by plants to convert sunlight into energy.
Parenchyma cells are important for photosynthesis and the transport of nutrients throughout the plant. They also play a role in the storage of food and water.
Secondary Growth
In secondary growth, the stem thickens as cells divide and expand. Secondary growth occurs in the vascular cambium, a layer of cells between the bark and the wood. The cambium produces new xylem cells on the inside and new phloem cells on the outside. Xylem cells are the cells that carry water and nutrients up the stem, and phloem cells are the cells that carry the food made in the leaves down the stem.
Growth Rings
Growth rings are the annual rings that are found in the cross-section of a tree trunk. They are caused by the change in the growth rate of the tree during the year. The tree will produce more wood in the spring and summer, when it is growing rapidly, than it will in the fall and winter. The growth rings are therefore wider in the spring and summer and narrower in the fall and winter.
