Plant Growth

Plant Tissues and Specialized Cells

Plant GrowthSpecialized CellsGuard CellsGuard cells create openings in the cuticle which allow gases (CO2) to enter the leaf for use in photosynthesis. These openings are called stomata. Guard cells can change their shape to open and close the opening.

Specialized CellsThe majority of stomata are located on the underside of leaves to reduce water loss (through evaporation) and allowing the upper surface of the leaf to be used for photosynthesis.

Meristematic CellsAnimals have stem cells that can differentiate into all the cells in our bodies.

Plants have a similar type of cell called meristematic cells. These cells have the ability to differentiate into specialized tissues.

Meristematic CellsMeristematic cells are the only cells in plants that will continue to divide throughout the life of the plant.These cells are only located in a few spots in the plantThe apical meristem tissueThe lateral meristem tissue

Apical MeristemsApical meristem tissue is located at the tip of the roots and shoots. This type of tissue allows the plant to grow taller.

Apical MeristemsApical meristem cells go through a 3 step process:Cell divisionElongationMaturation

Apical Meristems

As these cells elongate and mature the root is pushed further into the ground or the shoot grows further from the stem.

Apical Meristems

As the cells elongate they will differentiate into different types of cells in dermal, ground or vascular tissue.

Lateral Meristemslocated in the roots and shoots allows the plant to grow wider

Lateral Meristems

Lateral MeristemsTwo rings of lateral meristem tissue run the length of roots and shoots The outer ring produces new epidermal tissue called cork and the inner ring produces new xylem towards the inside of the stem and phloem towards the outside. The cork and phloem form the bark of trees and the xylem produces the rings we use to tell how old a tree is.

Lateral Meristems

Plant ReproductionBecause of meristematic tissue, some plants have developed a method of reproduction that does not require pollination of the ovule.

Vegetative ReproductionA plant can produce genetically identical clones by sending out new shoots or roots from meristematic tissue, that will grow new roots and an entire new plantExample. Strawberry plants

Vegetative ReproductionPoplar Trees

Vegetative ReproductionIf you cut a stem, root or leaf of a plant and place it in water, it can eventually grow new roots and produce a new plant with identical genetics