Leaves ample. 
Terrestrial plants. 
Indusium reniform; leaves 2--3-pinnate. 
18. Dryopteris. 
Indusium partly superior; leaves 2--3-pin- 
nate; plants delicate. LQ. Lage. 
Indusium inferior; leaves 2-pinnate, gland- 
ular pubescent; pinnae distant, divaricate. 
20. Woodsta. 
Indusium cup-shaped; leaves 3-pinnatifid. 
21. Dennstaedtia. 
Leaves of two kinds; sporophylls 3--7 dm. high, 
pinnate, segments closely rolled together. 
Sterile leaves 2-pinnatifid, 6--20 dm. high. 
22. Matteuccia. 
Sterile leaves triangular, pinnatifid. 
23. Onoclea. 
Aquatic plants. 
Leaves long-petioled, 4-foliolate. 24. Marsilia. 
Leaves linear, rigid ; stem corm-like ; plants small, 
sporangia axillary. 25. Lsoetes. 
Leaves minute or rudimentary. 
Plants robust, rush-like; stems hollow-jointed, 
simple or with verticillate branches. 
26. Egquisetum. 
Plants sinall, moss-like, erect or trailing. 
Spores uniform. 24. Lycopodium. 
Spores of two kinds. | 28. Selaginella. 
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