298 CONCERNING NOMENCLATURE. 



will be able to recognise the Order to which a given 

 species belongs and later will seldom have to consult the 

 Key for the genera, so noticeable do the family charac- 

 teristics become. The advanced student can nearly 

 always identify the growing fronds at a glance even 

 when they are sterile, but the beginner will usually need 

 good fruiting specimens to be sure of his species. It is 

 best to collect the fertile fronds rather early, before the 

 thin indusia have been disarranged or obliterated by the 

 growing sporangia and if the sterile fronds differ notice- 

 ably from the fertile, they too should be collected. The 

 rootstock, when not too large, should also be included. 



With good specimens in hand, the beginner should be 

 able to locate any of our ferns in the proper genus at 

 once by carefully following the Key. To show its work- 

 ings, let us suppose that the collector has found a speci- 

 men with rounded sori covered by a reniform indusium, 

 which he wishes to identify. Turning to the Key he 

 will observe that it branches somewhat like the veins of 

 the ferns themselves, dividing again and again and each 

 time more closely limiting the groups of species. It is 

 first divided into two sections numbered I. and II. 

 In one of these his species will be found. The first sec- 

 tion contains only ferns with " sporangia in spikes, pani- 

 cles or berry-like structures." His plant does not answer 

 this description so he passes on to section II. with " spo- 

 rangia on the under side of the frond." In this section 

 are two lesser divisions each marked with two stars (**). 

 The first contains only species without indusium and is 

 passed by for the section with " indusium present." Here 

 he finds several divisions all marked 4 and after reading 

 them he decides that his plant belongs to the one that 

 does not have its indusia " formed by the margin of the 



