Plant Tissues

Damnjanović Ivana

Internal Organization of the Plant Body

Tissue- a group of similar cells organized into a structural and functional unit.

Tissue System- a tissue or group of tissues organized into a structural and functional unit; larger units of the plant body.

Plant Tissues fall into two large categories:Meristematic, orPermanent (Non-Meristematic)

Plant Tissues

Meristematic Tissues

Meristems are places in plants where cell division is occurring.

During cell division, one cell becomes two cells.

Each new cell can also divide.

Meristematic Tissues

In this class we will discuss three kinds of meristems:

Apical MeristemsIntercalary MeristemsLateral Meristems

Apical Meristems

Primary growth of shoots and roots occurs as the cells of the apical meristem divide and elongate.

Shoot Apical Meristem

Root Apical Meristem

Root cap

Apical meristems cause PRIMARY GROWTH.

As cells in apical meristems divide and elongate, shoot tips and root tips grow longer. This increase in length is called primary growth.

Lateral Meristems – secondary growth in woody plants

Basswood – root in cross sectionBasswood – stem in cross section; 1, 2, 3 year old stems

Intercalary Meristems

Monocots, like grasses, have intercalary meristems which allow the leaves to grow

back after mowing.

Permanent tissues

Tissues that attained their mature form and perform pacific functions. They stop dividing

Types: Simple permanent tissues Complex permanent tissues

1. Parenchyma - cells are rounded in shape & have uniformly thin

walls found in all parts of the plants. - living at maturity, have large vacuoles - location Ieaf, stem (pith), roots, fruits

Functions:*basic metabolic function (respiration, photosynthesis (chIorenchyma in Leaf) *storage (potatoes, fruits, & seeds)*wound healing and regeneration

Simple permanent tissues

ChIorenchyma - A specialized parenchyma tissue found in the green parts of the shoot and performs photosynthesis.

ChIorenchyma

- differentiate from parenchyma cells & are alive at maturity

Arenchyma is the parenchyma in which the cells enclose large intercellular spaces that are filled with air.

It is characteristically found in aquatic floating plants.

Arenchyma

Storage of starch, protein, fats, oils and water in roots, tubers (e.g. potatoes), seed endosperm (e.g. cereals) and cotyledons

Storage parenchyma

Rhizodermis-absorption

Supporting ground tissues

Collenchyma

CollenchymaElongate in shape.Occur beneath the epidermis in young stems.Support young growing tissues.

Sclerenchyma- fibers and sclereids.Long or stellate in shape.Occur throughout the plant body.Support (strengthen) and storage.

Sclerenchyma

Sclerenchyma

SCLERIDS FIBERS