C.E.J. Botha and  DF Cutler

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    OUTLINE & QuickLinks

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Organization & Classification of Plant Parts

The principle of tissue system & organization

 

Dedication

 

Exercise 1 The use of the microscope

 

Exercise  2 The stem - variation in structure

 

Exercise  3

General leaf anatomy

 

Exercise  4
Variations in root structure

 

Exercise  5

The origin and development of secondary growth

 

Exercise 6

Anomalous growth in plants

 

Exercise 7

Evolution of the vascular system

 

Exercise 8  Secondary Wood Structure

 

Exercise 9 Structural adaptation

 

Online Glossary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cell arrangement and the influence this has on morphology

 

 

 

Classification:

 

What are you looking at? Stem? Leaf? Root? Angiosperm? Gymnosperm? Click on the link to see what kind of criteria need to be satisfied to be able to answer theses questions.

 

 

 

Core Objectives

 

 

 

Core Practical Outcomes

 

 

 

Tactical Outcome

 

 

 

Text Books

 

 

 

Appendices

 

Click here for a detailed look at the appendices

 

 

 

Dedication 

 

 

 

Legal

 

 

 

 

 

 

 

 

 

 

Plant Form and Function             

 

 

The Virtual Plant  has been developed primarily as a a hands-on aid to enable and encourage students to study and revise basic plant anatomy. The information that is presented here, is based on material from introductory courses in Plant Anatomy that we have offered in a University environment.

The material has been compiled so as to make it easy for beginners and advanced students alike, to access and use high quality images without the need to sit in front of a microscope for long periods of time. The overall aim of The Virtual Plant is thus to introduce and explore the anatomy of  stem, root and leaf - from a fundamental structure, function and adaptive perspective. We also introduce users to simple microscopic technique - we introduce the basic use of the microscope and explore some useful preparation techniques, which may be found by following the appropriate links to the appendices. The exercises present examples of some normal and some of the abnormal (anomalous) anatomical structures that exist amongst Angiosperms and Gymnosperms. The Virtual Plant includes information on plant structure-function interrelationships and adaptations, where this is considered to be appropriate.

The philosophy behind The Virtual Plant is relatively simple -- not everyone works quickly enough to be able to finish a practical session within the allotted time; not all students are lucky enough to have after-hours access to a microscope; nor do all students absorb information at the same pace. 

The Virtual Plant was designed to allow for self-paced, independent study, as these would  encourage key questions such as:-  "Why is the internal structure of plants so different?" or  "why is plant structure so regular and predictable in some, but not all plants?" Our primary objective was thus to introduce the reader to the internal structure of higher plants in their vegetative state. This material was produced as an adjunct to Plant Anatomy - an Applied Approach, in which we introduce the student to the principles of Plant anatomy, and examine some of its applications in more detail. Users are however advised to refer also to other texts, such as  Esau's Plant Anatomy and Anatomy of Seed Plants for additional reference material.

The Virtual Plant was designed to give more comprehensive coverage of the discipline than is commonly allowed for in modern Botany syllabi - which, sadly almost all neglect the importance of plant structure and associated issues in their undergraduate courses. Plant anatomy is unfortunately, becoming less studied at school, college and university level. Perhaps because the discipline is perceived as being a less glamorous laboratory-based option, compared to many other fields in Plant Biology. Arguably, lack of anatomical knowledge is proving disastrous. Fewer scientists really understand what they are dealing with when examining plant structure. Molecular biology for example, requires understanding of the localization of gene complexes in plants. In some cases, the researchers do not know (or understand, or worse, comprehend)  the difference between the cortex and stele in stems in even the most commonly-used plants, let alone understand the ontogenetic differences between a bundle sheath and a mestome sheath! Those of us who have a genuine interest in plant anatomy, believe that students need to be given a thorough grounding in basic plant structure. At the very least you will then be able to recognize the difference between stems, roots and leaves and should be able to recognise the cell and tissue types within which your interest lies.

We hope that the information presented here will be useful and will help you learn about the intermixture of structures that make up some otherwise fairly common land plants.  If you make good use of The Virtual Plant and the information it contains, we believe that you will gain a great deal of insight into plant structure and the interactive functionality of the whole plant. Additionally you may gain a greater appreciation for  this subject, and just why it is so important to understand plant structure.   

The techniques section contains useful, quite straight-forward procedures, which should benefit teacher and student alike. This section explores basic methods used in the preparation, preservation, sectioning, and staining of plant material. By making use of these techniques, you will  enhance or improve the image detail in your own material and, we hope, this excites greater interest in this fundamental botanical discipline. 

 

Structural Organization                       

 

 

 

 

The study of plant structure requires a good understanding of basic plant anatomy. It also requires the ability to recognize various structures such as stems, leaves and roots and to understand their cellular makeup.

Anatomy is without doubt, a core discipline in Botany.

 

Through the study of the internal structure of plants, you will be able to explore and learn more about the interrelationships between cells, and the tissues that these make up. Tissues in turn, make up the organs of the plant -- root, stem leaf, flower and fruit. You will see that  the same cell types and tissues occur in simple and complex tissues that make up plants. Plant anatomy therefore, must  involve studies at the light and electron microscope level. We should not forget that many of the diverse structures which make up the plant body, have a particular visible shape (morphology) and that the morphology is, in part, dictated by the internal arrangement of cells into tissues and thus into organs.

 

p The  principle of tissue systems

One of the most useful schemes developed for understanding general topographical anatomy, was devised by the German Botanist, Julius von Sachs (1875). His classification system has a great deal of merit - firstly, because it was relatively simple, and second, due to its wide applicability to the juvenile and young  leaf, stem and root.

According to von Sachs' scheme, there are three principle tissue systems: (1) The epidermis and cork layers which comprise the dermal system, (2) the conducting strands of xylem and phloem, which make up the vascular system, and (3) the remaining non protective and non-conductive tissues, which make up the fundamental or ground system.

 

 

The way in which cells are grouped will influence the plant's morphology -- For example:-

  • Angular stems may form discretely-localized mechanical (supporting) tissue - usually collenchyma and or sclerenchyma associated with the ridges in these stems.

  • Even though it floats on water, the water lily leaf requires some means of mechanical support. When we examine the internal structure of these leaves, we will find beautifully-adorned astro- and osteosclerieds

  • Canna leaves have large airspaces within their petioles and within the lamina of the leaf. These airspaces are formed by many-faceted, highly branched cells, termed aerenchyma.

  • Cut a pumpkin petiole and immediately, lots of sticky 'goo' emerges from the cut surface. This sap is rich in a wide variety of soluble carbohydrate and soluble proteins including enzymes, as well as other substances that are transported within a highly nutritious watery matrix. Many of these molecules are involved in the transport processes in some way. The majority of this sap is transported within highly specialized conduits called sieve tubes within the phloem tissue.

What is it? Stem? Root? Leaf? Our proven classification system will help you decide if the specimen you are looking at is derived from a stem, a root or a leaf. Click HERE to see some good arguments based upon microscopic examination that will help you make a decision for yourself!

Exploring the Virtual Plant            

 

The Virtual Plant is organized into distinct practical tasks. The first deals with the use of the microscope and the subsequent exercises explore issues relating to the basic concepts of the primary structure of the stem, root and leaf. Those that follow draw attention to secondary and anomalous growth. We then explore vascularization and secondary wood and end with a brief overview of structural plant adaptations. The sessions can be viewed in any order, which makes them ideal for study or refreshing knowledge.  It is important to note that this version of the The Virtual Plant does not cover all aspects of plant structure and  function -- but we do hope that you will become sufficiently interested and stimulated to look further, deeper and hence, understand more!

The Virtual Laboratory Sessions

 

 

 

The Microscope This introductory session is devoted to some basic principals needed in order to be able to make good use of a student microscope. These are, we believe,  generally poorly explained and and often forgotten! to enable you to make good use of a . We make use of simple examples and introduce the concept of magnification, field of view and  scale.

The Stem session explores monocotyledon, dicotyledon and gymnosperm stems - you can examine similarities and differences between them and have an opportunity to study examples of herbaceous and potentially woody stems as well.

The Leaf  session serves as an introduction to mesomorphic and non-mesomorphic leaf structure. There is a fairly detailed examination of the differences and similarities between some "typical" monocot, dicot and gymnosperm leaves. You will be exposed to structural changes related to, and induced by,  the type of photosynthesis (C3 C4 and CAM), as well as by habitat and environment for example.

The Root Here, the emphasis is on similarities and differences -- the monocot, the dicot and gymnosperm rooting systems. How do they differ? Are there features that they have in common, or is it simply cut and dried that they are all categorized and distinct from one another?

In the Secondary Growth in Plants exercise, we emphasize structural changes that occur during secondary growth in roots and stems. Included in this are  examples of changes that occur in the transition from an entirely primary plant body, to one in which new secondary vascular tissues and new protective layers are formed

Anomalous Growth in Plants In this session we introduce the concept of anomalous growth using some examples of  roots and stems. The examples chosen are but few but hopefully they will stimulate a basic understanding of the concepts involved in anomalous growth.

Evolution of the vascular system Vascularization was an essential step in the land migration, as well as the development of more efficient (but not necessarily larger) plants. This exercise examines some aspects of the evolution and development of the vascular systems in plants. We will look at some examples of hydrophytes, as well as some 'typical' land plants, which show variable structural features.

Secondary wood structure We explore the structure of secondary wood, which is not often done at the undergraduate level. We have selected species which give a reasonable introduction to the way in which the cells of the secondary xylem are laid down in different woods.

Structural adaptations The ability to adapt to environment was a key factor in a plant's survival, as well as the spread of land plants into less-hospitable areas. We explore and highlight some of these factors, and illustrate examples of some simple and complex ways in which plants have successfully adapted to their environments. A number of concept checks have been included as well , which will point to issues that you should research specifically for   issues relating to plant adaptations.

An Illustrated Glossary  has been included an illustrated glossary to aid in learning terms and words specific to plant anatomy. Many of these are Illustrated with appropriate images, to aid the learning process. You will need a Java-enabled and Java capable web browser to run these. Definitions are opened as new windows (approximately 400 X 600 pixels in size) on your desktop, and stay open for  30 seconds, to allow you you read the definition and look at any illustrations that are included.

 

 Core objectives:                                  

 

 

  • Gaining insight and ability by combining theoretical knowledge gained in lectures, with practical illustration through  observation of the images provided in the virtual plant, or from similar images observed using a compound microscope.

  •  Improving comprehension  by exploring the commonality of cells, cell distribution, tissues, organs - what do they have in common? Where & how do they differ? 

  • Improving perception of the variation seen in simple compared with complex interrelationships between the cells that make up tissues, and the tissues that make up organs of the plant.

  • Understanding more about plant structure and function relationships, through looking at architecture and the mechanics of plant construction.

  • Developing capacity to interpret the interrelationships between cells tissues and organs.

  • Learning about simple preparative techniques required for practical microscopic observation

Core practical outcomes                    

 

 

  • To recognize the difference between the structure of stems, roots and leaves

  • To gain a clearer understanding & improve interpretive skills in correlating what you see under the microscope with what you  illustrate on paper. Understand the concept of cellular and tissue variation.

  • To apply simple preparative techniques, required in specimen preparation and to be able to evaluate structure and implied function from these preparations. 

Tactical outcome                                

 

  • To develop understanding and ability to work with botanical specimens, using a simple compound microscope.

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Text Books                                           

 

 

In addition to the accompanying Plant Anatomy - an applied approach, we strongly encourage reference to texts such as Esau's The Anatomy of Seed Plants  and Plant Anatomy as these are sources of very valuable additional information.

 

The appendices have been compiled to help and assist you to make the most of general procedures which are needed to allow preparation and observation. How to cut sections, to stain them to draw what you see - this and more information is provided here.

Please remember: Many of the chemicals that are mentioned in the assignments and techniques that are used to fix, prepare and/or stain sections may well be hazardous to your health. Please exercise great care when using them.

 

Copyright Notice                                        

 

 

The right of Ted Botha and David Cutler to be identified as the Authors of this Work has been asserted in accordance with the UK Copyright, Designs, and Patents Act 1988.

All rights reserved. Instructors using Plant Anatomy: An Applied Approach by David Cutler, Ted Botha , and Dennis W. Stevenson may reproduce material from The Virtual Plant for classroom use. Otherwise, no part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, or recording, except as permitted by the UK Copyright, Designs, and Patents Act 1988, without the prior permission of the publisher.

First published 2007 by Blackwell Publishing Ltd

2007 by Ted Botha and David Cutler BLACKWELL PUBLISHING,

350 Main Street, Malden, MA 02148-5020, USA

9600 Garsington Road, Oxford OX4 2DQ, UK

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