FILICES. 257 



partially open, disclosing the spores inside. Each little globe is, 

 in fact, a spore-case or sporangium, so that here we have some- 

 thing quite different from what we have so far met with. Up to 

 this point we have found the sporangia collected into dots or 

 lines or clusters of some sort. In the Moonwort the sporangia 

 are separate and naked, and instead of bursting through the 

 action of an elastic ring, they open by a horizontal slit and 

 discharge their spores. In other Ferns, as the Osmunda, the 

 sporangia are somewhat similar, but burst open by a vertical 

 instead of a horizontal slit. 



Observe that the frond of Botrychium is not circinate in the bud. 



We shall now proceed to describe the commonly occurring 

 representatives of the Fern Family. 



ORDER CXIL FILICES. (FERN FAMILY.) 

 Flowerless plants with distinct leaves known as fronds, these 

 circinate in the bud, except in one suborder, and bearing on 

 the under surface or margin the clustered or separate sporangia 

 or spore-cases. 



Synopsis of the Genera. 

 SUBORDER I. POLYPODIA'CE^. (THE TRUE FERNS.) 



Sporangia collected into various kinds of clusters called sort. 

 Each sporangium pedicelled and encircled by an elastic jointed 

 ring, by the breaking of which the sporangium is burst and the 

 spores discharged. Sori sometimes covered by an indusium. 



1. Polypo'dliim. Fruit-dots on the back of the fronds near the ends 



of the veins. No indusium. Veins free. (See Fig. 231, Part I.) 



2. Adiun tuiii. Fruit-dots marginal, the edge of the frond being re- 



flexed so as to form an indusium. Midrib of the pinnules close to 

 . the lower edge or altogether wanting. Stipe black and shining. 

 All the pinnules distinct and generally minutely stalked. Veins 

 free. 



3. Ptc'ris. Fruit-dots marginal. Indusium formed by the reflexed 



edge of the frond. Midrib of the pinnules in the centre and 

 prominent. Veins free. Stipe light-coloured. (See Fig. 262.) 



4. Pellae'a. Fruit-dots marginal, covered by a broad indusium. formed 



by tbe reflexed margin of the frond. Small ferns with once- or 

 ^vice-pinnate fronds, tbe fertile ones very much like the sterile, 

 but with narrower divisions, Btlpe shining, purple or btfown, 



