Transport of water in plants

Introduction

Theories

Potometer Experiment

Xerophytes

Test

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You need to know details of the root and stem tissues mentioned on this page, especially the structure of root hairs and xylem tissue. To find out these details visit jkimball/BiologyPages

Photographs on this page by permission of Newcastle University.

On the College intranet the Images of Biology CD has pictures of all these tissues.

Currently under construction is our own page about plant tissues.

The Passage of Water Through a Plant

In this module you will learn about the structure of roots and stems, the route water takes to the leaves and the theories that explain why water moves up a plant stem. You will also learn how some plants are adapted to living in habitats where water is scarce.

Root Structure

In a root the vascular tissue is located in the middle. Water has to pass from the epidermis to the middle. There are two pathways by which this can happen, via the cells walls (apoplastic) or through the cytoplasm (symplastic).

Root hairs increase the surface area for the uptake of water.

Xylem is responsible for the transport of water up the stem.

Phloem is reponsible from the transport of of organic substances (e.g. the prodcuts of photosynthesis) both up and down the stem.

Cambium is the term used for the meristematic (capable of dividing) cells which form the vascular tissue.

Stem structure

In stem the vascular tissue is located in vascular bundles. These vascular bundles are arranged in a ring. Each vascular bundle contains phloem and xylem with a layer of cambium between them. On the outside of the vascular bundle there is often some sclerenchyma tissue, and this may form a complete ring between the vascular bundles.These cells have walls thickened with lignin and strengthen the stem.

Underneath the epidermis there may be a layer of collenchyma, whcih have a thick cellulose call walls. Most of the stem is composed of parenchyma. These are large, thin walled packing cells. vascular bundle vascular bundle vascular bundle

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