De I. VNER VEW D Forest Trees of the Pacific Slope

INTRODL JTION.
I ' * VI 's *
To meet as many as possible of these difficulties, common and striking
differences in the leaf and fruit forms of a number of trees have
been specially pointed out in illustrations or descriptions.
VALUE OF FULL-SIZED ILLUSTRATIONS.
Nearly all figures show leaves, etc., of natural size. In the writer's
experience, nothing is more helpful, particularly to untrained students,
than illustrations practically the exact size of specimens they
will find in the field. In reduced illustrations of the leaves, fruits,
and seeds of some trees distinctive characters are lost, so that even
specialists find them useless. Reduced figures are used only when the
natural sizes of the object are too large for the pages of this book. It
is believed, however, that in these cases distinctive characters have
not been lost.
OMISSION OF ARTIFICIAL KEYS FOR IDENTIFICATION.
Keys leading up to the identification of families, genera, and species
are omitted, chiefly to prevent further delay in publication. They
appear to be little used, if at all, by lay students, who prefer to
identify trees by elimination, i. e., by comparing the specimen with
the illustrations until a " picture " is found that " fits." This method
is whollv unscientific, but is nevertheless the one which busy,
untrained lovers of trees are most likely to follow.
TECHNICAL NAMES OF TREES.
The technical nomenclature does not correspond wholly with that
of any one author. Tree names adopted here are based upon the
generally accepted law of priority, which demands that the earliest
tenable name be retained. The period in which this law is here held
to be operative is from I 753, when the general application of binominal
names of plants began. This is in accordance with the usage of
most dendrologists.
Many changes of technical names have been necessary since the
publication of the author's " Nomenclature of North American Trees "
and " Check List of the Forest Trees of the United States," upon
which the nomenclature is based. It is regrettable, but inevitable,
that authors should differ in judgment regarding the retention of
certain tree names, even if they do accept as a working principle
priority of publication for every name used. The intricacies of
nomenclatural law are too great to be discussed here, but for the sake
of illustrating one of the many points of disagreement among dendrologists,
the two names Sequoia wellingtonia and Sequoia washingtoniana,
now retained for the bigtree of the California Sierras, are
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