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BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

TABLE OF CONTENTS

1. OUTCOMES FOR THIS MODULE...... 3

2. NOTES...... 3

3. INTRODUCTION TO TREES...... 4

4. WHAT IS A TREE ? ...... 4

5. TREE IDENTIFICATION ...... 4

6. ...... 5 6.1. Simple Leaves ...... 5 6.2. Compound Leaves ...... 5 6.2.1. Pinnately compound leaves ...... 5 6.2.2. Bi-pinnately compound leaves ...... 5 6.2.3. Compound shapes...... 6 7. HOW DID PINNATELY COMPOUND LEAVES EVOLVE ?...... 6

8. LEAF CHARACTERS ...... 7 8.1. Common Leaf Shapes ...... 7 8.2. Leaf Apices ...... 8 8.3. Leaf Bases ...... 9 8.4. Leaf Margins ...... 10

9. BARK...... 11

10. THORNS AND SPINES...... 11

11. FLOWERS AND FRUITS...... 11

12. INTRODUCTION TO TREES - PART 2...... 11

13. BIBLIOGRAPHY ...... 12

2 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

1. OUTCOMES FOR THIS MODULE 2. NOTES

On completion of this module, you will: The notes for this module were compiled by Marion Melville. • Have an understanding of the use of the following important characteristics to identify No part of these notes may be reproduced, copied trees: or utilised in any form or by any means, without the permission of the author or the management of o Shape and growth form Bushveld Training Adventures. o Leaves and bark o Thorns or spines

o Flowers o Fruit

• Have an understanding of the various leaf shapes and know them by name. • Recognise the most common leaf margin types

• Know the shapes of the most common leaf bases • Know the shapes of the most common leaf

apices • Identify the differences between the various leaf arrangements, including:

o Opposite leaf arrangement o Sub-opposite leaf arrangement

o Alternate leaf arrangement o Spiral leaf arrangement

o Whorled leaf arrangement

• Describe the differences between o Simple leaves

o Pinnately Compound leaves o Bi-pinnately compound leaves

• Understand the use of a Dichotomous Key as an aid to tree identification • This set of notes on the Introduction to Trees and Grasses consists of three sections, namely:

o Introductions to Grasses o Introduction to Trees – Part 1

o Introduction to Trees – Part 2

Important icons which accentuate key notes:

³A definition

tTake Note

3 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

3. INTRODUCTION TO TREES ³A SHRUB is a woody, perennial Fortunately, trees are to be found everywhere in with two or more stems arising from or near Africa, and if one has been lucky enough to have the ground. It differs from a tree in that it is explored this vast continent of ours, one is left in smaller and does not have a trunk or bole. awe of the large diversity, as well as the great beauty of trees. When one stands in the shade of an old giant many hundreds of years old, one can’t Trees vary greatly in shape and form. They may be help but imagine the array of wildlife that must have huge and dominate the skyline, for example, the rested under it, used it for shelter or simply passed Baobab – Adansonia digitata, or have no leaves at it by. all, as is the case with the Euphorbia family. Then there is also the Ploughbreaker – Erythrina zeyheri, A show of colour as the leaves turn red and yellow a tree which has a large underground stem and in the autumn, or a mass of flowers in the spring produces annual aerial flowering shoots which will raise many questions by interested nature resemble veld flowers! lovers, so the ability to identify and understand the different tree species is a must for any field guide or 5. TREE IDENTIFICATION nature enthusiast. Furthermore, trees have interesting medicinal and cultural uses, the The ability to identify trees is acquired over time, knowledge of which will greatly enhance your and is not an instant acquisition attained without learning experience, and eventually enlighten those putting in the necessary work and time. to whom you pass on this interest. Because botanists largely identify and classify trees One would think that because trees are firmly according to their floral structure (flowers) and rooted in the ground and are not prone to moving fruit, it is often difficult for the amateur botanist or away swiftly and disappearing behind a rise, that learner field guide to identify trees, when both they would be easily identified. flowers and fruit are absent. It is therefore important that other general characteristics are also Not always so! Two examples of a single species used in the identification process. These may vary greatly in size and shape, but with the use characteristics include: of information contained in this introduction, you will be well on your way to enjoying the skill of tree • Leaves – are they simple or compound, hairy or identification. smooth. What is the leaf margin like? • Bark – is it smooth, rough, peeling or blocky Remember that your identification skills will improve in leaps and bounds with practise, and also as you • Thorns – are they straight or hooked, white or become more familiar with a particular area or blue vegetation type. • Latex – is it present, and if so, is it milky or clear 4. WHAT IS A TREE ? • Growth form – do the branches grow upwards There are various definitions recorded of what many or do they droop, is the canopy rounded or flat authors consider to be a realistic description of a and is the foliage dense or sparse. tree. The accounts differ considerably, but suffice to In this publication, all the above characteristics will say, a tree grows above a certain height, has a be simply explained. Study them carefully and be perennial stem, a vascular system and a crown of sure to remember them. foliage. For the purpose of this course, a tree is described as follows:

³A TREE is a perennial woody plant, with

a single (usually) main stem exceeding a height of 3m, a trunk diameter of 15cm or more and a

distinctive upper crown.

A tree is not to be confused with a shrub, which is described as follows:

4 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

6. LEAVES 6.2. Compound Leaves

Leaves are divided into two different configurations; A compound leaf is composed of several similar parts (leaflets), attached oppositely, sub-oppositely o Simple leaves, and or alternately on either side of a central rachis. o Compound leaves

³The RACHIS is the central axis of a 6.1. Simple Leaves pinnately compound leaf, to which the leaflets are attached. Simple leaves have a single blade which is attached to a petiole (a stalk). This in turn is attached to a stem. Simple leaves may also be sessile and The leaflets resemble small simple leaves and can attached directly to the stem. Simple leaves are by be confused as such. far the most common type and are undivided. Compound leaves may also be bi-pinnately SIMPLE LEAF MORPHOLOGY compound, in other words, twice compound. These leaves are found on Acacia and Albizia

Apex species, amongst others. Margin 6.2.1. Pinnately compound leaves

PINNATELY COMPOUND LEAF Vein A pinnately compound leaf is once divided with Base many leaflets arranged alternately or oppositely Petiole along a common axis.

Axillary bud This axis is called the Stipule rachis.

³A STIPULE is a leaf-like structure found

at the base of the petiole. A STIPULAR SCAR is left on the stem when they are discarded.

Simple leaves occur in various shapes. 6.2.2. Bi-pinnately compound leaves

BI-PINNATELY COMPOUND LEAF

Then there is a bi- pinnately compound leaf, which is twice divided.

In other words, the Bi-lobed Leaf Heart-shaped Leaf leaflets attached to the rachis (the same as in a compound leaf) are divided once again and then called pinnules.

Lobed Leaf Oval Leaf

5 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

6.2.3. Compound leaf shapes PARIPINNATE LEAF IMPARIPINNATE LEAF COMPOUND LEAF SHAPES

PALMATE or DIGITATE TRIFOLIATE or TRIFOLIOLATE

A paripinnate leaf An imparipinnate leaf ends with a pair of ends in a single leaflet leaflets only

An example is: A good example is: Pod-mahogany – Marula – Afzelia quanzensis Sclerocarya birrea

7. HOW DID PINNATELY COMPOUND LEAVES EVOLVE ? TRIFOLIATE or BIFOLIATE or TRIFOLIOLATE BIFOLIOLATE During an evolutionary process over millions of years, certain trees adapted their leaves, to fit more efficiently into their environment and to suit conditions found there. ³COMPOUND LEAVES have different Superfluous leaf areas where moisture could be lost configurations, the most common of which are diminished over time, leaving smaller leaves explained below: surrounding existing veins. • BI-FOLIATE LEAF – A compound leaf with 2 leaflets, for example, Cholophospermum mopane

• TRI-FOLIATE LEAF – A compound leaf with 3 Once compound leaves leaflets, for example, Rhus species. • DIGITATE LEAF – A digitately compound leaf, has several leaflets attached at the same point, to the end of a petiole, for example, Vitex rehmannii and the Baobab, Adansonia digitata.

As previously explained, a compound leaf is divided Twice compound into leaflets, which may number from two to many. leaves

Each leaflet resembles a small leaf which is attached to a rachis, either oppositely, sub-oppositely or alternately.

However, they may be arranged in two different Simple leaf configurations:

HOW COMPOUND LEAVES EVOLVED BTA o Paripinnate, and o Imparipinnate

6 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

8. LEAF CHARACTERS LANCEOLATE Narrowly pointed lance When identifying trees, it is important to realise that shaped leaf, widest leaf characters vary greatly from one genus to the near the base. other, and even between species. Some leaves are hairy, some glabrous (without hairs). Margins An example is: (edges) may be entire (smooth), toothed or wavy Barberton Resin-tree – depending on the species, whilst some leaves may Ozoroa barbertonensis be bi-coloured (dark green above, much lighter below). All these and similar features, together with leaf arrangement, enable the use of a Dichotomous Key as an aid to identification.

It must also be borne in mind, that some leaf characters and shapes are seen slightly differently OBLANCEOLATE Narrow leaf, tapering by different authors. What is oval to one may be towards the base and elliptic to another, especially when the leaf shape widest in the distal falls on the cusp of either. (top) half.

The most common leaf characters follow: An example is:

8.1. Common Leaf Shapes Velvet Raisin – Grewia flava LEAF SHAPES

ROUND The leaf is generally as broad as it is long.

An example is – LINNEAR A very narrow leaf with Wild Pear – Dombeya parallel sides, being at rotundifolia least 5 times as long as broad.

An example is: OVATE A leaf roughly ‘egg Lance-leaved Guarri – shaped’, with the Euclea linearis widest part in the basal (lower) half.

An example is:

Buffalo-thorn – Ziziphus mucronata

OBOVATE An inverted ‘egg shape’ with the widest part in the distal (apical/top) half.

An example is:

Puzzle-bush – tThe leaf samples used on this page to Ehretia rigida illustrate leaf shapes, are not necessarily from

the examples given in the boxes alongside them

7 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

8.2. Leaf Apices ARISTATE As in mucronate, but the bristle tip has to be LEAF APICES hard and pin-like to be aristate. ACUTE / TAPERING The margins diminish evenly towards the tip An example is: at approximately 45° to 60°. Spine-leaved Monkey- Orange – An example is: Strychnos pungens

Red Milkwood – Mimusops zeyheri

ATTENUATE The leaf tip is drawn

out into a long narrow different leaf shapes point. on the same tree

An example is: Leaf shapes found on certain trees, are not always what Forest Bell-bush – they seem! Mackaya bella Pictured on the left, is a collection of leaves picked from the same tree, a Puzzle-bush (Ehretia rigida). NOTCHED The leaf has a small V shaped indentation at It often happens, that the the apex. best, youngest or most attractive sample is collected An example is: for identification, without due thought, as to whether Forest False Spikethorn or not the leaf is a true

Putterlickia verrucosa representative of the majority of leaves on the bush or tree.

Take your time when OBTUSE / ROUNDED Rounded or blunt at the collecting a specimen, apex. study your tree carefully,

An example is: and above all, be sure to collect a characteristic

Large-fruit Bushwillow – sample to work from. Combretum zeyheri

MUCRONATE A leaf having a short, sharp and very fine bristle point borne at

the tip of the leaf.

An example is: t The leaf samples used on this page to

Cat-thorn – illustrate leaf apices, are not from the examples given in the boxes alongside them. Scutia myrtina

8 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

8.3. Leaf Bases

LEAF BASE TYPES PELTATE A leaf, usually round, that has a petiole CUNEATE A leaf tapering to a originating from a point wedge at the base on the leaf, other than the margin An example is: An example is: Russet Bushwillow – Combretum hereroense Wild Poplar – Macaranga capensis

TRUNCATE The leaf base is square- SESSILE cut or ends abruptly. The leaf has no petiole (stalk) and is joined An example is: directly to the stem.

Lowveld Fig – An example is: Ficus stuhlmannii Common Sugarbush – Protea caffra

CORDATE A leaf base that is lobed or heart shaped.

An example is:

Mallow Raisin – Grewia villosa

ASYMMETRIC The leaf base in not equal on both sides. It is either oblique or lopsided.

An example is:

Buffalo-thorn – Ziziphus mucronata

DECURRENT A leaf in which the leaf blade continues or runs down the petiole.

An example is:

Cat’s Whiskers – t. The leaf samples used on this page to Rotheca myricoides illustrate leaf bases, are not necessarily from the examples given in the boxes alongside them.

9 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

8.4. Leaf Margins

LEAF MARGIN TYPES LOBED ENTIRE An even smooth margin A leaf having deep lobes along the margin An example is: An example is: Velvet Sweetberry – Bridelia mollis Snot Apple – Azanza garckeana

SERRULATE A finely toothed margin CILIATE The leaf margin is An example is: edged with fine hairs.

Sandpaper Raisin – An example is: Grewia flavescens Bladdernut – Diospyros whyteana SERRATE A margin that is saw- toothed with regular forward pointing sharp teeth.

An example is: UDULATE The margin of the leaf undulates from the Cape Blackwood – Maytenus peduncularis above the upper surface to below the under surface DENTATE A sharp, coarsely toothed margin with An example is: teeth that generally point outwards. Small-leaved Guarri – Euclea undulata An example is:

Forest Saffron – Elaeodendron croceum

CRENATE A scalloped margin with regular rounded teeth.

An example is:

Tamboti –

Spirostachys africana

CRENULATE As above, but with very tThe leaf samples used on this page to finely scalloped margin illustrate leaf margins, are not from the examples given in the boxes alongside them.

10 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

9. BARK 10. THORNS AND SPINES

Another important identifying feature of trees, is The two above elements are easily confused by the believe it or not, bark. inexperienced and more often than not, incorrectly named. Although bark may be variable within species due to climatic conditions and locality, it is generally o THORNS are curved spines, originating recognisable to a greater or lesser degree. Bark from stipules. Thorns are found on Acacia varies in colour and texture, and in most cases, spp. amongst others. diagnostic of a genus. o SPINES are sharp, straight, pointed and hardened structures, usually modified from Listed below are some examples: dwarf lateral shoots. Leaves can grow from spines. An example is the Small-leaved PEELING OR FLAKING BARK (BUT SMOOTH) Sickle-bush (Dichrostachys cinerea). • Peeling Plane – Ochna pulchra o PRICKLES are sharp pointed outgrowths of • Blue Thorn – Acacia erubescens the epidermis or bark. • Common Star-chestnut – Sterculia rogersii 11. FLOWERS AND FRUITS COARSE AND BLOCKY BARK • Leadwood – Combretum imberbe Flowers and fruits are sometimes so striking, that a tree can be identified by using these features alone, • Tamboti – Spirostachys africana although it makes good sense to verify your • Velvet Bushwillow – Combretum molle ‘diagnosis’ by checking other identifying features on the tree. COARSE, FISSURED OR ROPEY BARK Flowers and fruits will be discussed in more depth in • Ouhout – Leucosidea sericea the TREES notes. • Silver Cluster-leaf – Terminalia sericea • Camel-thorn – Acacia erioloba 12. INTRODUCTION TO TREES - PART 2 COARSE AND CORKY BARK • Boekenhout – Faurea saligna The morphology of leaves has now been explained, but they are not the only entities used as an aid to • Wild Pear – Dombeya rotundifolia the identification of trees. • Cabbage Tree – Cussonia spicata Bark, colour and texture, leaf arrangement and COARSE AND PEELING BARK habitat are also extremely important and indispensable characters of tree identification. • Marula – Sclerocarya birrea • False Marula – Lannea schweinfurthii Part 2 starts off with explanations on LEAF ARRANGEMENT, another handy tool, followed by COARSE WITH THORNS, KNOBS OR BUMPS help on using identification keys and tips to make • Knob-thorn – Acacia nigrescens the process so much easier. • Small Knobwood – Zanthoxylum capense Now go to Part 2 of this publication, to learn how to • Thorny-rope Flat-bean – armata identify trees using a Dichotomous Key.

RELATIVELY SMOOTH BARK • African White Stinkwood – Celtis africana

• Jacket-plum – Pappea capensis • Shepherds-tree – Boscia albitrunca

11 BUSHVELD TRAINING ADVENTURES INTRODUCTION TO TREES AND GRASSES 2

13. BIBLIOGRAPHY

COATES PALGRAVE, K, PALGRAVE, M.2000. Trees of southern Africa. Struik Publishers, Cape Town.

GRANT, R. & THOMAS, V. n.d. Sappi tree spotting – Bushveld including Pilanesberg and Magaliesberg. Jacana, Johannesburg.

MELVILLE, M. 2006: Photographs and illustrations used with permission.

POOLEY, E. 1997. The complete field guide to trees of Natal, Zululand and Transkei. Natal Flora Publications Trust, Durban.

SCHMIDT, E., LOTTER, M. & McCLELLAND, W. 2002. Trees And shrubs of and Kruger National Park. Jacana, Johannesburg.

VAN WKK, P. & VAN WYK B. 1997. Field guide to trees of southern Africa. Struik Publishers, Cape Town.

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