NOTES FOR THE BEGINNER. 



II. — WHERE TO FIND AND HOW TO IDENTIFY THE FERNS. 



IN studying the higher plants we find that they are grouped into 

 families and genera according to the flowers they bear. How- 

 ever different other parts of the plants may be, the flowers of 

 each genus do not differ in any essential particular. In ferns the 

 sori serve instead of flowers for the determination of the genera. 

 Each genus affects a certain type of sorus and, while there are 

 endless variations in the size and arrangement of this, the shape 

 and structure remain as constant as the flowers of a genus. 



In the northeastern states, two families, the spleenworts and 

 the shield ferns, divide the honors in regard to numbers, each con- 

 taining more than twice as many species as any of the other genera. 

 Their numbers make an early knowledge of how to distinguish 

 them very desirable. Fortunately this is very easy, for the spleen- 

 worts (Asplenium) bear their spores in short linear sori on the 

 backs of the fronds (Fig. 3), while the shield ferns (Dryopteris) 

 bear theirs in round or kidney- shaped sori (Figs. 1 and 2). In 

 both genera the sori are covered with an indusium. The shield 

 ferns are also called wood ferns, because they are mostly lovers of 

 deep shade, though some do not fear the sun if growing in wet 

 places. Seek for them on the borders of swamps, in wet wood- 

 lands, ravines and dry, rich woods. So nearly do some species 

 resemble others that the student frequently passes them by, but, 

 after having the differences pointed out, wonders how he ever 

 could have missed them. 



Many of the larger spleenworts are also lovers of the wood- 

 lands, but the smaller and weaker members seem to crave the 

 protection of the rocks, and will be found on the ledges, especially 

 of limestone, often in full sunlight. At a glance the sori will tell 

 the genus to which they belong. The only apparent exception is 

 the lady fern {A. Filix-fcemina), which delights to grow along old 

 roadsides. When young the sori are curved in horseshoe shape, 

 and the novice might take the plant for a Dryopteris, but as it 

 grows older, the sori straighten out into the conventional spleen- 

 wort shape. 



The polypody [Polypodium) must not be taken for a Dryop- 

 teris because of its round sori, for if we look closely we shall find 

 that its sori are not covered with an indusium as those of Dryop- 



