Table Of ContentTHE BOOK OF LEAVES
A LEAF-BY-LEAF GUIDE TO SIX HUNDRED
OF THE WORLD’S GREAT TREES
ALLEN J. COOMBES
EDITED BY ZSOLT DEBRECZY
THE UNIVERSITY OF CHICAGO PRESS
Chicago and London
ALLEN J. COOMBES is coordinator of scientific collections at the Herbarium and
Botanic Garden of the University of Puebla, Mexico. He was previously botanist at the
Sir Harold Hillier Gardens in Hampshire, England. He is the author of several books on
trees and plants and was president of the International Oak Society from 2006 to 2009.
ZSOLT DEBRECZY is research director of the International Dendrological
Research Institute, Inc., Boston, Massachusetts, USA. He holds a PhD in botany and
began his career as curator of the Bryological Collection in the Botanical Department of
the Natural History Museum, Budapest, Hungary. He is the author of several books
focusing on temperate-zone woody flora and vegetation.
CONTENTS
Foreword
Introduction
What is a tree?
What is a leaf?
Leaf function
The variety of leaves
Leaf shape and arrangement
Leaf anatomy
Understanding plant names
Identifying tree leaves
The leaves
Appendices
Glossary
Resources
Index by common name
Index by scientific name
Acknowledgments
FOREWORD
Leaves are a true miracle of nature. They perform a job that science still only
dreams of fully understanding: they transform dissolved minerals and other
elements into the organic matter that eventually forms the shoots, leaves,
roots, flowers, and fruits that create the Earth’s rich layer of humus and soil,
and build its wondrous forests and habitats. Leaves, or specifically the
chlorenchyma cells within the mesophyll, make possible the material
connection between the Sun’s energy and life on Earth.
Evergreen leaves can provide significant year-round interest. This Cherry Laurel (Prunus
laurocerasus), which is commonly grown for its attractive foliage as well as for providing
shelter, is a classic example.
Morphologically, leaves are modified, flattened shoot-systems. Many
scientists in the field of evolutionary morphology believe that over geological
time, plants’ lateral outgrowths gave rise not only to leaves but also to
reproductive organs such as petals, sepals, carpels, and stamens.
Leaf shape varies hugely, both within and between species. Yet the basic
character of a leaf is usually typical enough to help with species identification.
So, The Book of Leaves is about tree identification as well as about leaves.
Other identifiers, such as flowers and fruits, are ephemeral, but the leaves
remain throughout a tree’s growing season. A leaf can be simple; that is, with
a single blade adjoining the stem; or distinctly compound, with few or many
leaf-parts (leaflets). A leaf can be entire, shallowly to deeply lobed, or cut
toward the central vein. Characters of the leaf’s surface provide additional
identifiers, such as whether or not the leaf is hairy, and whether the hairiness
is sparse or dense, rough, or soft.
The leaf selection introduced here is limited to the temperate zone, that
Era (starting about 65 million years ago) to the present. This flora first
appeared in the northern part of a much warmer Earth (an average
temperature of 72°F/22 °C compared to 57 °F/14 °C today). It gradually
evolved to resist physiological cold—primarily by being deciduous in winter
or, if evergreen, by other morphological and physiological strategies. This
ability saved most or many species as the planet gradually cooled, reaching its
low-temperature minimums in periods starting some half-million years ago.
As for leaves from the southern hemisphere, in this book they are
represented by a somewhat more moderately cold-resistant flora that
survived and evolved in South America and New Zealand and in the
southernmost part of Australia, particularly the wet conditions of Tasmania
and the mountains of southern Australia. The Book of Leaves thus covers a
large segment of the trees that can be observed in forests, or in arboreta,
throughout the temperate world.
Documenting trees and photographing leaves is a true pleasure for any
nature lover. Leaves are intrinsically beautiful, and can inspire deep feelings.
Go for a walk in an arboretum, and you might notice how similar the related
temperate-zone species can be, even though one may be from North America
and the other from southern Asia. This is because they are indeed closely
related; climatic differences and millions of years of divergent geological
history have merely blurred their similarities. This book you now hold is,
one might say, a kind of paper arboretum, a place where trees and leaves that
the eons have dispersed have been successfully and satisfactorily reunited.
Zsolt Debreczy
The European Wild Pear (Pyrus pyraster) is one of a few species in its genus to have small,
rounded leaves.
INTRODUCTION
“Nature will bear the closest inspection. She
invites us to lay our eye level with her smallest
leaf, and take an insect view of its plain.”
, 1839
HENRY THOREAU
In spite of their importance to life, their abundance, and their presence over a
large proportion of the year, leaves are perhaps the least appreciated part of a
tree. We often talk of beautiful flowers or wonderful bark, but leaves are
generally accorded a mention only for their brief, but often spectacular, fall
color. As L. Frank Baum wrote in The Land of Oz “For the common folks are
like leaves on a tree, and live and die unnoticed.”
The Hubei Crab Apple (Malus hupehensis) has an ovate form. Whatever their shape, all leaves
are adapted to perform a range of complicated functions.
Leaves are all around us, we see them every day, but do we really look at
them? To many of us, a leaf is just that, a leaf, but I hope this book goes some
way to showing the amazing diversity of shapes that leaves have, and that it
encourages closer observation. The leaf of every species is different in one
way or another—not only in the shape, but in many other respects, too. In
some cases the differences may be small, but noticing them is just a matter of
training the eye.
It is interesting to see how different people react when trying to identify a
tree. The inexperienced will usually stand at some distance away while those
with more knowledge will be close up, holding the leaves, feeling the texture,
and trying to detect any scent. Invariably the first thing the most experienced
people will do is to turn the leaf over, since the lower surface holds most
Description:Of all our childhood memories, few are quite as thrilling, or as tactile, as those of climbing trees. Scampering up the rough trunk, spying on the world from the cool green shelter of the canopy, lying on a limb and looking up through the leaves at the summer sun almost made it seem as if we were ma
