FERNS. ID'J 



From this time on we shall have a great diversity of rootstocks 

 and fronds to characterize the different species and genera of ferns 

 that present themselves to our notice. Tlie structural characters 

 of the most prominent groups of these are represented by the 

 specimens on the screens. I will endeavor to explain them to 

 you briefly b}' means of some actual specimens which I have 

 selected for this purpose. 



While it is theoreticall}' true that all the varying rootstocks of 

 ferns are morphologicall}' related, and are all simply more or less 

 modilicatious of a true stem, it is also true that these modifications 

 have resulted in certain structural types that fix the habit of the 

 species to which they belong. Two of these types are so marked 

 and distinct, that if we were to base our classification of ferus 

 upon habit alone we might separate them into two large groups, 

 one having upright rootstocks and the other horizontal. But other 

 important considerations enter into our system of classification, so 

 that it often happens that both- of these types of rootstock are 

 represented in one and the same genus. The first of these is 

 properly designated by the term caudex, meaning an erect stock or 

 stem, and the second by the term rhizome, or rhizoma, meaning a 

 running or creeping stock or stem with a horizontal growth. There 

 are various modifications of these types which must be passed over 

 for want of time, but most of them may be seen among the speci- 

 mens on the board, and are designated on the tickets. 



The example which I have here is the nearest approach to the 

 true caudex of a tree fern yet known to our United States Flora, 

 and belongs to a variety of Aspidium conterminam^ growing in 

 Florida and first found by J. Donuell Smith of Baltimore. In this 

 species the caudex rises nearly a foot above the surface of the 

 ground. Professor Robinson has noticed some indications in this 

 direction in our common Rock Shield fern, Aspidiuvi marginole, 

 and a very clever and acute lad}^ botanist of the Pacific slope, Mrs. 

 Braudegee, recently called attention to some remarkable develop- 

 ments in the caudex of Osmunda in California. 



The best examples of a rhizoma we shall find in Pteris agrnlina, 

 our common Brake, and Woodivardia Virginica, the Chain fern. 

 In both of these ferns the stout rootstock extends under ground 

 for a distance oftentimes of from ten to twelve feet or more. 



In summing up the structural characters of ferns we have only 

 time to say that the rootstock is the true stem of the fern, and the 



