[PDF]How To Identify Plants

H. D. HARRINGTON
L. W. DURRELL


TO IDENTIFY PLANTS





Digitized by the Internet Archive
in 2010


http://www.archive.org/details/howtoidentifyplaOOharr


HOW TO IDENTIFY PLANTS


Also by H. D. Harrington


Manual of the Plants of Colorado


HOW
TO IDENTIFY
PLANTS


by


H. D. HARRINGTON


Professor of Botany and Curator of the Herbarium
Colorado State University


Illustrated by L. W. Durrell


Emeritus Professor of Botany
Colorado State University


tue SWALLOW PRESS unc


CHICAGO


Copyright © 1957 by H. D. Harrington and L. W. Durrell
All rights reserved
Printed in the United States of America


Published by

The Swallow Press Incorporated
1139 South Wabash Avenue
Chicago, Illinois 60605


This book is printed on 100% recycled paper.


ISBN 0-8040-0149-9
LIBRARY OF CONGRESS CATALOG CARD NUMBER 57-4731


PREFACE


The purpose of this book is to provide practical
help for those interested in learning the special
technique of identifying plants. It is based on the
writer's experience in watching Several thousand be-
ginners acquire this skill. Unfortunately there is
no easy way, no "royal road" to this knowledge. Like
everything else worth while in life it takes effort
and perseverance. An attempt is made here to smooth
out some of the rough places on the road but the real
job must be done by the student himself.


The procedure followed in dealing with the nec-
cessary technical terms is to present the common ones
in a special chapter where related concepts can be
compared with each other. It is suggested that these
terms be memorized by the student. The more unusual
ones can be looked up as needed in the illustrated
glossary that makes up the final chapter. The defin-
itions of many of these terms have been deliberately
simplified in order to give a practical instead of a
theoretical treatment. The real test in drawing up
these definitions was how the term was used in the
average manual for the identification of plants. The
illustrations are intended to present the general
concept and therefore are not drawn from actual speci-
mens, A picture is a static thing but the concept it
represents may be a variable one. Sometimes a series
of drawings is used to represent this range of varia-
tion - when only one is given it shows an average.
The specimen will rarely if ever look exactly like
the drawing but must conform to the general concept
of the descriptive term as illustrated by it.


Chapter
Chapter
Chapter
Chapter


Chapter


Chapter


Chapter
Chapter
Chapter
Chapter
Chapter


Chapter


Chapter
Chapter


Chapter


I




VI


VII


VIII


XII


XIII


XIV


TABLE OF CONTENTS


Introductvonm 2. 2. 5. 2 a a 6 = s a
How plants are classified. ... .
Common names and scientific names.
Terms relative to the flower...


Terms relative to the
inflorescence .g. : sm. « owe ois


Terms relative to underground
parts e o e © e e e e o a e e e o


Terms relative to the stem . . . à
Terms relative to the leaves...
Terms relative to surfaces ... o
General terms. . . « « © «© è e è o
Fruits and seedS . . m « « « « « «


Use of keys in plant
identification. . . e «. è è è è o


Collecting and pressing plants. .
Manuals and floras . . >. > ə ə èe o


Illustrated glossary . m.e > . . e à


l
7
12
17


31


36
39
42
57
65


71


83
90
99


124


Chapter I


INTRODUCTION


WHY WE NEED TO IDENTIFY PLANTS.


Many people are interested in learning the
names of the plants growing about them. The motives
behind this desire are probably many but it may be
of interest to list some of the commonest ones as ex-
pressed to the writer.


l. To satisfy a general curiosity.

Usually the first question that comes to mind
when one is confronted with a new and strange object
is, "Now what is the name of that?"


2. To be able to talk or write about the plant.
When an object must be designated again and
again then some sort of name for it becomes a real
need. AS one person expressed it to the writer,
"Why, even a wrong name is better than no name at
alli" It might be possible to talk about plants or
keep written records concerning them, if each was
designated by an arbitrary number, but the procedure
would certainly be both tedious and unsatisfying.


3. To be able to look up information about the plant,
The great storehouse of human knowledge con-
tains recorded facts concerning many species of
plants. Questions may arise like the following. Is
the plant edible? Is it poisonous to man or to his
livestock? How palatable is it to animals? Does
it have a tendency to become a weed and if so how can
it be controlled? How should it be treated in culti-
vation? Does it have any special legend or interest-
ing story connected with it?


These questions and many others may be answered
very completely in various publications. However,
all this information is ordinarily unavailable to the
student if the name of the plant is unknown, If the
first question is "What is the name of that?" then


the second often is, "What good is it; what is it
used for?" Knowing the name of a plant opens the
door to the answer to such a question.

HOW NAMES OF PLANTS CAN BE LEARNED.


The names of plants can be learned in at least
two ways.


l. Ask Someone who knows.





This method is satisfactory when dealing with
rather few numbers and when your authority is con-
stantly at hand. Probably this is the most enjoy-
able way of learning the names of plants, as a boy
who becomes acquainted with trees by having them
pointed out by his father. However, few of us have
this opportunity of constant expert advice. Add to
this the fact that our trusted authority may turn
out to be a broken reed and we may learn a lot of in-
correct names! It is just as hard to learn the wrong
names as the right ones. The sad fact seems to he
that the less some people know about plants the surer
they are in making snap identifications! A real exe-
pert is always cautious, sometimes exasperatingly so!


2. Learn to identify the plants yourself.

This is the best and surest way because you can
determine plants anywhere and at any time. All that
is necessary is the correct manual or flora and the
Skill to use it. As indicated in the preface this
skill is not easy to acquire. The writer periodical-
ly receives a desperate request, "Please tell me an
easy method of learning to identify plants.” There
just isn't any such thing. Popular treatments and
picture books of plants may be satisfactory if all
that is wanted is a superficial viewpoint but they
can never lead to a real fundamental knowledge of the
subject.


WHY PLANT IDENTIFICATION CANNOT BE MADE EASY.


l. There is a special knack involved.

Some people pick up this skill more quickly than
others. Discouragement always comes at the beginning
when progress seems slow.


2. Technical descriptive terms must be mastered.


These terms are freely used by the manuals be-
cause they have a definite and exact meaning that
cannot be expressed in ordinary language, at least
with reasonable brevity. For example, two related
species may differ only in the type of hairs on the
leaf surface, one "tomentose", the other "pilose",
This is a clear cut difference to one who understands
these terms but almost impossible to state briefly in
anything but botanical parlance. At least three ways
of mastering these technical terms are possible.


(1.) Deal with each new term as it is encoun-
tered. Almost every manual includes a
glossary explaining these terms.


(2.) Attempt to memorize all or most of the
terms used by the manual and try to under-
stand their exact meaning before starting
the identification proper.


(3.) Drill on the important terms that are con-
tinually used and look up the others as
needed.


The writer believes that the third method is the
best for students. the first one slows the work down
so much that a beginner becomes discouraged. The
second method would surely work out but it would cer-
tainly be monotonous and uninteresting. The last pro-
cedure allows one to understand these commonly used
terms better by giving a chance to compare related
ones. For example the exact meaning of "lanceolate"
as a leaf shape (Fig. 107) becomes apparent when one
compares it with the related "linear" (Fig. 106) and
"ovate" (Fig. 108). This third plan is the one on
which this booklet is based. The next eight chapters
are given over to a discussion of the terms that have
been found to be most important. It is suggested
that the student becomes so familiar with them that
they need not be looked up each time they are used.
An illustrated glossary is presented as the last
chapter to aid in the understanding of the less com-
monly used terms.


Some students find it worth while to keep a list
of each new term with its definition. These can be
reviewed from time to time. However, some of the


names on this list may be uncommon and may not be
used again for some time. Form the habit of check-
ing the meaning of each new term as it comes up.
Trying to get the meaning from the context, comparing
it with its contrasting term, skipping over the
phrase and trusting to luck - all these methods may
work in certain cases but can never lead to a real
skill in identifying plants.


3. Constant practice is necessary.


This means that a student must be really in
earnest about acquiring the skill. Either a stern
necessity or an unflagging determination (or both)
are prerequisites in learning to identify plants.


The most efficient method of acquiring this
technique is to learn it under the direction of some
competent teacher where help can be given when it is
most needed. However, many people in various walks
of life have picked up this discipline entirely on
their own without the aid of a formal course in the
subject. Some of them have even become world wide
authorities on special plant groups or on the flora
of a limited area. A few have even wound up as
teachers of the subject. Remember, do not allow
yourself to become discouraged at first, Acquiring
a skill or any special knowledge is much like rolling
up a snowball - it appears to grow so slowly at first
but enlarges with satisfying rapidity when it begins
to attain a large diameter,


NECESSARY EQUIPMENT.
1. The manual or flora covering the area.


These will be discussed in a later chapter.


2. Hand lens.





A good lens is a necessity, probably something
between an 8 X (8 times magnification) and a 12 X.
The lower powered ones are larger and give a bigger
field with a longer working distance. The higher
powered ones are smaller and therefore easier to
carry but although the image is magnified more it is
not so clear. A good lens has a reasonably long
working distance and gives a reasonably clear image
even out toward the edge of the field. A common type
of hand lens is shown in Fig. 1A.


£





Fig. 1.
3. Forceps and needles.


These implements allow for the handling of min-
ute parts. The forceps are shown in Fig. 1 D., a
needle in Fig. 1 E.


4. Razor blade.


A sharp blade is needed in order to make thin
sections of flower ovaries. An ordinary knife blade
is not satisfactory even when very sharp. A straight
edge razor works nicely if kept keen-edged. Most
Students prefer to purchase a package of one-edge
safety razor blades, discarding the dull ones from
time to time. A holder for razor blades is on the
market and may prove to be a convenience. Such a
razor knife is shown in Fig. 1 C.


The blade should be used with a pulling or push-
ing diagonal motion, not a chopping action but more
on the order of manipulating a saw than an axe. This
is illustrated in Fig. 39 in Chapter IV.


5. Rule.


Be sure the rule is graduated in centimeters and
millimeters; practically all manuals and floras give


measurements according to the metric system. Such a
rule is shown in Fig. 1 B.


Chapter II


HOW PLANTS ARE CLASSIFIED


Before the technique of identifying plants is
developed the student should have in mind the way
plants are grouped together and how these various
groups are organized. It is often amazing for a be-
ginner to observe how strikingly plants can be seg-
regated into various divisions and subdivisions. For
example, species of the genus Rosa the world over
have an unmistakable stamp of the "rose" upon then.
Man has attempted to recognize and name these natural
groupings. It is true that intergradations do exist
in some groups with exasperating regularity. We are
apt to notice these exceptions as we would one ob-
streperous child among a group of well behaved ones
and forget the fact that the great majority of plants
actually seem to group themselves naturally into
large and small units.


NEED FOR CLASSIFYING.


Several hundred thousand species of plants exist
in the world. A recent estimate placed the number at
335,000. The single state of Arizona was listed by
Kearney and Peebles in their Arizona Flora as having
132 families, 907 genera and 3,370 species. So even
the flora of one state poses a definite problem in
organization; somehow we must get the plants pigeon-
holed. In a herbarium it is necessary to file the
Specimens away according to some system. We could
file them away in some artificial arrangement - as
for example trees, shrubs and herbaceous plants - or
we could arrange them alphabetically by name. Botan-
ists have chosen to try to organize, classify and
group plants according to what they think has been
their evolutionary development, that is, in a phy-
logenetic system with related plants contiguous and
unrelated plants far apart.


A TYPICAL SYSTEM.
Species - the plants of one kind.


Genus - a group of related species.
Family - a group of related genera.


7


Order - a group of related families.

Class - a group of related orders.
Subdivision - a group of related classes.
Division - a group of related subdivisions.


The four divisions of the plant kingdom as out-
lined in many manuals and books on general botany
are:


1. Thallophyta (Thallophytes). The algae and
ungi.

2. Bryophyta (Bryophytes). The mosses and
Tiverworts.

3. Pteridophyta (Pteridophytes). The ferns and
fern allies.

4. Spermatophyta (Spermatophytes). The seed
plants.


The four groups are sometimes called phyla in-
stead of divisions and some authors may not organize
them into categories of equal rank. You will want to
become familiar with the way your manual outlines
these major groups. Most ordinary books for the i-
dentification of plants include only the last two,
the so-called vascular plants. Of course special
manuals and treatments are available for the detern-
ination of species in the Thallophyta and Bryophyta
divisions.


CLASSIFICATION OF THE CINNAMON ROSE.


Let us see how the cinnamon rose would fit into
our scheme of classification.


Division - Spermatophyta - the seed plants as
opposed to the other three divisions.


Subdivision - Angiospermae - plants with seeds
>>>