Fructification. 



29 



lines, or may even be spread in a stratum over tiie entire under 

 surface of the frond. They may be indusiate or non-indusiate 

 according as they are covered or naked ; and the indusia may be 

 inferior (attached below the sorus), as in Woodsia (Fig. 12), or su- 

 perior as in Aspidium (Fig. 11), or of various intermediate meth- 

 ods of attachment. 



FiG.S., Fia. 4. Fio. 6. 



Fig. 3. — Enlarged sessile sporangium of TrichomjaTies radicana, Swz. (Original.) 

 Fig. 4. — Sporangium of Schiz3ea p^^tUa, Pursh, showing the apicil ring. Much en- 

 larged. (Original.) 



Fig. 5. — Sporangium of Osmunda regalis, L., showing the rudimentary ring. Enlarged. 

 (Original.) 



32. In the other sub-orders of Filices the sporangia are va- 

 riously arranged. In the Hymenophyllace^ or filmy ferns the 

 flattened sporangia are sessile along a filiform receptacle and are 

 surrounded with a complete transverse ring. At maturity they open 

 vertically, (Fig. 3). In the Schiz.eace^ the sporangia are ovatei 

 surroundedat the apex by a complete ring, and open by a longitud- 

 inal slit. (Fig. 4). In the Osmundace^ or flowering ferns the 

 sporangia are larger, globose and naked, with 

 the mere trace of a transverse ring, and open 

 longitudinally. (Fig. 5). 



33. In Order Ophioglossace^ the spor- 

 angia are not reticulated, possess no trace of a 

 ring, open by a transverse slit, and are various- 

 ly spiked and panicled. (Fig. 6). 



The various methods of fructification can 

 be best understood by describing the peculiar- 

 ities of the various genera in regular succes- 

 sion and noting the variations occurring in the 

 sections or sub-genera. By this means we will 

 arrive at a belter understanding of the princi- 

 ples of fern classification as discussed in a 

 future chapter. As the subject of venation is 

 closely connected with that of fructification, it 

 will be treated in the same connection. 



Fig. G.' Enlarged spo. 

 rangia of Botrychium 

 temaium, Swz. (Orig- 

 inal.) 



