How to Know the Ferns (7th ed)/Chapter 6
HOW TO USE THE BOOK
Before attempting to identify the ferns by means of the following Guide it would be well to turn to the Explanation of Terms, and with as many species as you can conveniently collect, on the table before you, to master the few necessary technical terms, that you may be able to distinguish a frond that is pinnatifid from one that is pinnate, a pinna from a pinnule, a fertile from a sterile frond.
You should bear in mind that in some species the fertile fronds are so unleaf-like in appearance that to the uninitiated they do not suggest fronds at all. The fertile fronds of the Onocleas, for example, are so contracted as to conceal any resemblance to the sterile ones. They appear to be mere clusters of fruit. The fertile fronds of the Cinnamon Fern are equally unleaf-like, as are the fertile portions of the other Osmundas and of several other species.
In your rambles through the fields and woods your eyes will soon learn to detect hitherto unnoticed species. In gathering specimens you will take heed to break off the fern as near the ground as possible, and you will not be satisfied till you have secured both a fertile and a sterile frond. In carrying them home you will remember the necessity of keeping together the fronds which belong to the same plant.
When sorting your finds you will group them according to the Guide. The broad-leaved Sensitive Fern, with its separate, dark-green fruit cluster, makes its way necessarily to Group I. To Group II goes your pale-fronded Royal Fern, tipped with brown sporangia. As a matter of course you lay in Group III the leaf-like but dissimilar sterile and fertile fronds of the Slender Cliff Brake. The spreading Brake, its reflexed margin covering the sporangia, identifies itself with Group IV. The oblong fruit-dots of the little Mountain Spleenwort carry it to Group V, while the round ones, like pinheads, of the Evergreen Wood Fern announce it a member of Group VI.
The different ferns sorted, it will be a simple matter to run quickly through the brief descriptions under the different Groups till you are referred to the descriptions in the body of the book of the species under investigation.