48 Our Native Ferns. 



94. Sub-Orders. Tribes are grouped into sub-orders, accord- 

 ing as they agree in the characters of the sporangium, its shape, 

 method of discharging its spores, and the existence, character, 

 or absence of a ring. 



95. Orders. Ferns are often classed in a single order, but in 

 accordance with the latest researches of the best structural botan- 

 ists, they are separated into three distinct orders, Filices, Mar- 

 ATTiACEiE and Ophioglossace^, which are distinguished prin- 

 cipally by the mode in which the sporangia are developed, and 

 also by other minor characteristics. Two of the orders are well 

 represented in our flora. The Marattiace« are mostly confined 

 to tropical regions. 



g6. Classification. The true idea of classification is the 

 grouping together of objects according to essential and funda- 

 mental resemblances. Every system is more or less artificial, 

 yet there is a continual approach toward the true natural system, 

 which is the ultimatum of scientific classification. That the 

 various systems of classification as applied to ferns, as well as 

 their position in the vegetable kingdom, may be better under- 

 stood, the following outlines from a few of the leading botanists 

 is appended. 



97. Position of Ferns in the Vegetable Kingdom. The Cryp- 

 togamia or flowerless plants formed class xxiv. of the Linnaean 

 system of classification and contained the following orders : * 



I. Filices. (Ferns.) 



II. Equisetacea. (Scouring Rushes.) 



III. LvcopoDiNEiE. (Club Mosses.) 



IV. Musci. (True Mosses.) 

 V. Hepatic.*;. (Liverworts.) 



VI. Alg^. (Sea Weeds.) 



VII. LiCHENES. (Lichens.) 



VIII. Fungi. (Mushrooms.) 



98. Lindley, in his " Vegetable Kingdom," divides the asex- 

 ual or flowerless plants into two classes, Thallogens and 

 AcROGENS, the latter containing eleven families, among which 

 are Filices and Ophioglossace^. 



* Linnfeus recognized only fonr orders : Nos. n., ili., v. and yii. have been added by 

 later botanists. 



