FERNS. 193 



They have also in a general way a strong family resemblance 

 one to another, so that one becoming familiar with a few forms 

 may readily distinguish other ferns by their' general likeness, even 

 if unable to determine any particular species without close study. 

 There is, however, a great diversity of minor characters by which 

 different species, and even genera, are to be determined, and 

 which require careful stud}'. 



Some are evergreen, often with glossy foliage, some are thick 

 and leather}' in texture, while others are herbaceous, thin, and 

 almost transparent. Between these extremes there is every grada- 

 tion. !Some are smooth, while others are more or less covered 

 with scales, avooI, glands, or powdery substances. 



These special characters, for the most part, bear some relation 

 to the situations in which they grow ; so that, given the special 

 characters of any particular species, one may not only be able to 

 indicate the localities where it is most likely to be found, but 

 to point out the best mode of treatment for its cultivation. 



Thus the larger and coarser ferns, as a rule, grow in moist, 

 shady situations, such as damp woodlands, bogs, swamps, and 

 ravines, while the smaller ferns, and are generally to be looked 

 for along mountain ranges, in dry, exposed situations, and those 

 with a woolly or farinaceous covering, especially in regions where 

 they are subject to long periods of great heat and drought. 



Ferns vary no less in size than iu the-ir minor characters. The 

 smallest known fern is a southern species which grows in masses, 

 like a moss, on dripping rocks in Alabama, with fronds only from 

 one-half to three-fourths of an inch in height. In striking contrast 

 to this minute fern are the magnificent tree ferns of tropical 

 regions, some of which grow to the extraordinary height of from 

 sixty to eighty feet with immense spreading fronds. 



Ferns are widel}' but uuequall}' distributed in the proportion to 

 flowering plants of about one to eight, to one to two hundred, 

 according to the climatic conditions of the various countries Avhich 

 they inhabit. 



As they most abound where shade, warmth, and moisture 

 prevail they reach their highest state of perfection in the humid 

 atmosphere of the tr-opics. Here their growth is luxuriant and 

 wonderful, attaining the enormous proportions of gigantic trees 

 with huge trunks rising to a great height, and surmounted with 

 correspondingly enormous fronds. As we pass into cooler and 

 13 



