PTERIDOPHYTA 



Fernworts. 



Plants of two distinct generations, in one consisting of a plant- 

 body (sporophyte), which has stems containing vascular tissue 

 and produces spores asexually, in the next, developing from the 

 spore, consisting of a thalloid-body (gamctophyte or prothallium), 

 which bears the sexual reproductive organs (archegones and anther- 

 ids). The plant-body develops from the oosphere within the 

 archegone, after being fertilized by spirally coiled motile bodies 

 (spermatozoids), produced by the antherids. 



KEY TO THE FAMILIES. 



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 bv a transverse 



sUt arranged in spik^ or panicles. 1. Ophioglossaceae. 1038 



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



opens elastically. . ^ . 2. Polypodiaceae. 1040 



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



borne m sporocarps. 



Plant rootmg in the mud; leaves 4-foUolate, petioled. 3. Marsiliaceae. 1050 



Plant mmute. floating; leaves entire or 2-lobed. 4. Salviniaceae. 1051 



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



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



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

 Leaves awl-like, elongate, borne on a short tliick corm-like 



ACEAE. 1051 



T , ^^^ ^ ^ ^ , . ^' ISOETACK^E. 1053 



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



Spores uniform, minute. 7. Lycopodiaceae. 1054 



Spores of two kinds, microspores and macrospores. 8. Selagineli^^ce ve 105G 



Family 1. OPHIOGLOSSACEAE. Adder's Tokgue Family. 



Leafy succulent plants with fleshy rhizomes and fibrous, often fleshy, 

 roots. Leaves (fronds) erect to reflexed, but not coiled in vernation, con- 

 sisting of a sterile simple or compound leaf-blade and one or more stalked 

 spore-bearing spikes or panicles (sporophylls), all borne on a common stalk. 

 Sporanges bivalvular, formed from the interior tissue of the sporophvUs. 

 Prothalha underground, not green, monoecious. Spores of one kind. 



1. BOTRYCHIUM Sw. Mooxwort, 



Terrestrial plants, with erect rhizomes and usually only one frond. Roots 

 clustered, fleshy. Common stalk with more or less of its length below ground, 

 the bud of the frond of the following year enclosed within its hollow base. Veins 

 free, forking. Sporophyll single. Sporangia distinct, globose, arranged in two 

 rows. 



Frond-bud without hairs. 



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



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

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



1. B. simplex. 



* Contributed by Miss Margaret Slosson. except the families Equisetaceae, Isoetaceae, 

 and Selaginellaeeae, and the key to the families. 



1038 



