PTERIDOPHYTA 



KEY TO THE FAMILIES. 



Page 

 Leaves usually broad, entire or dissected, not scale-lilte; 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. Ophioglossaceab. 280 



Vernation spirally coiled; sporangia- membranous, provided with a ring, which 



opens elastically. 2. Polypodiacbae. 280 



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



borne in sporocarps. 



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



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



Leaves scale-like or awl-like; moss-Ulce or rush-like plants, 



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

 Ulce. I 5. Equisbtaceae. 283 



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



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



6. Isoetaceae. 283 



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



Spores uniform, minute. 7. Lycopodiaceae. 283 



Spores oftwo kinds, microspores and macrospores. 8. Selaginbli-aceae. 284 



Family 1. OPHIOGLOSSACEAE. Adder's Tongue 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 conmionly cuneiform 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 



lunulate or fan-shaped. 2. B. Lunaria. 



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

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

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

 deltoid. 4. B. lanceolalum. 

 Frond-bud hairy. 



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



5. B. virginianum. 

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

 Sterile leaf-stalk 1—4 cm. long; plant very stout and fleshy. 6. B. Coulleri, 



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



7. B. silaifolium. 



Family 2. POLYPODIACBAE. Fern Family. 



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

 Veins of the sterile fronds netted. 1. Onoclea. 



Veins of the sterile fronds free. 2. Pteretis. 



Fertile and sterile fronds foUaceous, aUke 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 spUt into spreading lobes. 3. WOODSI.V. 

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

 finally thrown back or evanescent. 4. FiLix. 



Indusia superior. 



Indusia peltate. 5. Polystichxjm. 



Indusia orbicular-reniform, adherent at the sinus. 



Mid veins and midribs luiited at a wide angle; fronds usually provided 

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



6. Thelypteris. 

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

 hairs. 7. Dryopteris. 



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. 



8. ASPLBNIUM. 

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

 fertile vein and more or less recurved upon it. 9. Athyridm. 



280 



