This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Within the above area there are over 4600 recognized species, more than three times the number in Bentham's Illustrated Handbook of the British Flora. To illustrate all these in a work of moderate size and cost, only parts of each plant could usually be figured, and these mostly below life-size. To exhibit full-page illustrations would have added fourfold to the bulk of the work, and the consequent more limited sales would have necessarily increased the price in a much greater proportion, and thus have thwarted the primary objects, viz., to supply a work adapted to general circulation and use. On the other hand, it was found that any considerable further reduction of the figures in order to reduce the size of the work, would be at the sacrifice of the clearness and usefulness of the illustrations.
In the general plan adopted and in giving parts only of the larger plants, it has been the constant aim to make the reduction of each figure as little below life-size as possible, to select the most characteristic parts for illustration and to preserve the natural proportion. In these respects, it is believed, the present work will be found to be at least not inferior to that above named and often superior.
The cuts are all from original drawings for this work, ether from life or from herbarium specimens, though reference has constantly been made to published plates and figures. All have been first drawn life-size from medium-sized specimens, and afterwards reduced to the proportion indicated by the fraction near the bottom of each cut, most of them being from 1/2 to 2/3 of medium life-size. By this method the illustrations do not suffer from the use of a magnifier, but are improved by it and retain their full expression.
The large number of additional figures in the second edition and the incorporation into the main text of the appendix to the first edition, have necessitated the renumbering of the figures consecutively.
Enlargements of special parts are added in most of the illustrations in order to show more clearly the floral structure, or minute organs, or the smaller flowers. These are in various degrees of enlargement, not deemed necessary to be stated. The figures are uncolored, because coloring, except in costly work, obscures the fineness of linear definition and injures the cuts for descriptive and educational uses.