Although the ferns and their allies are a small group of about 10,000 species compared to the 275,000 species of seed plants, their lineage is a long and noble one going back to the carboniferous period 300 million years ago when they were the dominant form of plant life in the swap-forests.

Ninety-seven species of attractive group of plants are described in this this column, about one-quarter of the total found on the whole continent north of the Mexican border. Each species is described in detail, and the description is supplemented by a clear line drawing and a map showing its distribution as represented in the larger collections of the continent. The drawings are original and based on specimens carefully selected the show diagnostic details. Keys are provided to the families, genera, and species so that a plant can be placed quickly and easily in its proper category. The book also includes a list of chromosome numbers, a list of species grouped by distribution patters, and a glossary of the technical terms used.

This is the first comprehensive treatment of the pteridophyte flora of the large area comprising Oregon, Washington, British Columbia, the Yukon Territory, and Alaska to the Arctic Ocean. In this region, climate varies from warm to arctic cold, precipitation varies from 200 inches annually to less than 10, and altitude varies from sea level to over 20,000 feet.

Arranged in alphabetical order by family, genus, and species, this volume brings together in convenient form the critical judgments of experts who have written about the pteridophyte flora of the Northwest. Both the professional biologist and the naturalist will find much in this volume of interest and value.