164 ASPIDIUM CRISTATUM. CRESTED SHIELD-FERN. 



between the end of the division and the mid-vein. As we get 

 further north we find the fertile fronds deeply pinnatifid ; and 

 in such cases the fruit dots form a line alongside the mid-rib of 

 the ultimate divisions. Our Fig, 2, drawn from a dried speci- 

 men from New England, exhibits this character. Other botanists 

 have noted that the fruit dots are sometimes nearer to the mid- 

 vein than to the margin, and in other cases the reverse, but in 

 the typical form they are about midway. Again in the more 

 northern specimen. Fig. 2, we see that the upper portion of the 

 fertile divisions are very coarsely toothed. It is probably from 

 these coarse segments that the species derived the name 

 cristatum, or crested, a character nearly wanting in the form 

 illustrated. 



The Crested Fern is a native of the north of Europe as well 

 as of the United States, and has been known from the time of 

 Linnaeus, who named it Polypodhim cristatum, the genus Aspidhim 

 not having been founded till Swartz established it in 1800. 

 Since that time succeeding botanists have endeavored to make 

 other genera out of Aspidiimi, and have carried our Crested 

 Fern into their several classifications. Thus we find it in some 

 works referred to as Lastrcra cristata, NcpJirodiufii cristatiun, 

 PolysticJuun cristatinu, and Djyopteris cristata. It is worthy of 

 note that Professor Asa Gray, who in the earlier editions of his 

 " Manual " gave it the last name, has abandoned it in the later 

 one from whence our description was taken ; and this shows how 

 nice and how imperfectly understood are the natural limits which 

 divide the genera of ferns. Considering Chapman's Aspidiiim 

 Floridanum to be only the Crested Shield-Fern, we find it along 

 the seaboard Atlantic States, barely reaching Kentucky and Ohio 

 westwardly, and becoming more common as it goes northward to 

 Canada. It is sparingly found in England, but becomes more 

 abundant as it approaches eastwardly the American continent. 



Explanations of the Plate. — l. Fionds of Pennsylvania specimens, with the stipes short- 

 ened. 2. Norlhcin form with crested lobes, from a dried specimen. 



