PTERIDOPHYTA 



KEY TO THE FAMILIES. 



Page 

 Leaves usually broad, entire or dissected, not scale-like; fern-like plants. 

 Spores of one kind, minute, borne in sporanges. 



Vernation not spirally coiled; sporangia ringless, leathery, opening by a transverse 



slit, arranged in spikes or panicles. 1. Ophioglossace.ve. 280 



Vernation spirally coiled; sporangia membranous, provided with a ring, wliich 



opens elastically. 2. Polypodiaceae. 280 



Spores of two kinds, minute microspores (male) and larger macrospores (female). 



borne in sporocarps. 



Plant rooting in the mud; leaves 4-foliolate, petioled. .3. Marsiliaceae. 283 



Plant minute, floating; leaves entire or 2-lobed. 4. Salvixiaceae. 283 



Leaves scale-like or awl-like; moss-like or rush-like plants. 



Sporanges in an apical cone, borne imder peltate bracts; stem usually hollow, rush- 

 like. .5. EQUISETACE.i.E. 283 



Sporanges in the axils of small leaf-like bracts; stem soUd. 



Leaves awl-Uke, elongate, borne on a short thick corm-Uke caudex; water plants. 



6. ISOET.ACEAE. 283 



Leaves .scale-like, flat, borne on a distinct stem; land plants. 



Spores miiform, minute. 7. Lycopodiace.\.e. 283 



Spores of two kinds, microspores and macrospores. 8. Sel.vgixellaceae. 284 



Family 1. OPHIOGLOSSACEAE. Adder's Toxgue Family. 



1. BOTRYCHIUM Sw. Moonwort. 



Frond-bud without hairs. 



Sporophyll and sterile leaf-blade not completely bent down in the bud. 



Sporophyll erect in the bud, the sterile leaf-blade erect or with the apex bent over; 

 segments of the sterile leaf commonly cmieiform or fan-shaped. 



1. B. simplex. 

 Sporophyll and sterile leaf-blade with the apex or upper part bent down in the bud. 

 Sterile leaf-blade sessile or subsessile, once pinnately divided, the segments 



hmulate or fan-shaped. 2. li. Lunaria. 



Sterile leaf-blade usuaUy stalked, entire to twice pinnately divided, the seg- 

 ments mostly oblong or ovate. 3. B. negleclum. 

 Sporophyll and sterile leaf-blade completely bent down in the bud; sterile leaf-blade 

 deltoid. 4. B. lanceolatum. 

 Frond-bud hairy. 



Common stalk open along one side at base, usually long ; sterile leaf-blade sessile. 



.5. B. lirginianum. 

 Common stalk completely closed at base, usually short; sterile leaf-blade stalked. 

 Sterile leaf-stalk 1^ cm. long; plant very stout and fleshy. 6. B. CouUcri. 



Sterile leaf-stalk usuallj- 5 cm. long or more; plant not so fleshy, often slender. 



7. B. silaifuUum. 



Family 2. POLYPODIACEAE. Ferx Family. 



Fertile fronds, with contracted berry-like or necklace-Uke subdivisions, not foUaceous. 

 Veins of the sterile fronds netted. 1. OxorLEA. 



Veins of the sterile fronds free. 2. Pteretis. 



Fertile and sterile fronds fohaceous, alike or differing; veins free. 



Sori on the under surface of the fronds, each provided with a special indusium not 

 connected with the margin of the frond. 

 .Sori roundish. 



Indusia inferior or attached at base at one side of the sorus. 



Indusia inferior, stellate or split into spreading lobes. 3. WoODSl.v. 

 Indusia attached at base at one side of the sorus, at first arched over it, 

 finally thrown back or evanescent. 4. FiLix. 



Indusia superior. 



Indusia peltate. 5. PoLTSTlCHUil. 



Indusia orbicular-reniform, adherent at the sinus. 



Mid veins and niidril^s imited at a wide angle; fronds usually provided 

 with true hairs, consisting of a single cell or a single row of cells. 



6. THELYPTERI-S. 



Mid veins and midrib imited at a very acute angle; fronds lacking true 

 hairs. 7. Dryoptekis. 



Sori oblong or linear, or shaped like a horseshoe or shepherd's crook. 



Sori all straight or rarely sUghtly curved, single on the sides of the veins. 



S. ASPLEXIUM. 



Sori, at least in part, shaped like a horseshoe or shepherd s crook, crossing the 

 fertile vein and more or less reciu-ved upon it. 9. Athy'RIU.m. 



280 



