delion he has, he must follow through the key and use the
scientific name.

There is in this book, therefore, no necessity of learning or using
scientific names. The less critical may be satisfied with an English
name, and others may use the scientific names as they see fit.

=Possible Errors.= In using this book, care must be taken to compare all
the lines under each number with the plant, and to use judgment in
selecting the right one. While faulty observation or poor judgment may
lead to error, a mistake is usually due to carelessness in not following
correctly the reference at the end of the line chosen. If one reaches a
number in which none of the lines of description agrees with the plant,
it is very probable that he has made a mistake at an earlier stage of
the identification, and he should then begin anew.

It has been the intention of the author to make the key as nearly as
possible proof against errors of judgment. For example, the Indian
Turnip may be sought under either Group 3 or Group 4; the Matrimony Vine
may be identified either as a shrub or as an herb, and numerous other
similar examples may be discovered.

=Botanical Information Needed.= It is presumed that those using the book
will be familiar with the parts of the flower and with the commoner
descriptive terms applied to leaves. Unusual terms have been avoided as
far as possible, but those which do occur, as well as the simpler ones,
are explained in the glossary.

In general, only those characters have been used in the keys which can
be observed without a magnifying glass and without dissection of the
flower.

In several groups of plants, reference is made to the fuller
descriptions to be found in the Manuals. The standard manuals for
Michigan are Gray's New Manual of Botany, 7th edition (American Book
Company, $2.50), and Britton and Brown, Illustrated Flora of the
Northern States and Canada (Chas. Scribner's Sons, $13.50). These books
may be consulted in most school or public libraries.

All dimensions are expressed in the metric system. For convenience, it
may be stated that 25 millimeters (mm.) are about equal to one inch; 1
centimeter (cm.) to two-fifths of an inch; 1 decimeter (dm.) to 4
inches; and 1 meter (m.) is a little more than 3 feet.

KEY TO GROUPS

1a. Trees, shrubs, or woody climbers, with stems which last from year to
year Group 1, =WOODY PLANTS=, p. ix.

1b. Herbaceous plants