352 THE PLANT PHYLA 



Phylum IX. PTERIDOPHYTA. The Ferns 



Chlorophyll-green, small, sexual plants (gametophytes), pro- 

 ducing a large-leaved, rooted generation (sporophyte). 

 (Here restricted to the ferns alone and 

 including about 3,800 sp.) 



Class 20. EUSPORANGIATAE. Old-fashioned Ferns. Spor- 

 angia developed from internal cells. 



Order OPHIOGLOSSALES. Adder-tongues. Gametophyte 

 tuberous, subterranean; sporophyte 

 with large leaves, some parts sporog- 

 enous. 



Family 1. Ophioglossaceae. Including Ophioglos- 



sum, Botrychium, etc. 



Order MARATTIALES. Marat tias. Gametophyte flat, 

 green, superficial; sporophyte with 

 large compound leaves; sporangia 

 hypophyllous. 



Family 2. Marattiaceae. Large tropical ferns, from 

 the Paleozoic to the present. Angi- 

 opteris, Marattia. 



Order ISOETALES. Quillworts. Gametophytes dioecious 

 rounded; sporophyte with erect, 

 crowded, narrow leaves; sporangia 

 epiphyllous, basal. 



Family 3. Isoetaceae. Aquatic, rush-like plants. 



Isoetes. 



Class 21. LEPTOSPORANGIATAE. Modern Ferns. Spor- 

 angia developed from superficial cells. 

 Order FILICALES. Land Ferns. Spores of one kind; game- 

 tophytes foliose, monoecious. 



Family 4. Osmundaceae. Sporangia globose, split- 

 ting vertically. Osmunda. 



Family 5. Schizaeaceae; 6, Gleicheniaceae; 7, Maton- 

 iaceae; 8, Parkeriaceae. 



Family 9. Cyatheaceae. Tree Ferns. Sporangia 

 compressed, splitting transversely. 

 Alsophila, Cyathea, Dicksonia. 



Family 10. Hymenophyllaceae. Filmy Ferns. Spor- 

 angia compressed, splitting vertically. 

 Hymenophyllum, Trichomanes. 



