66 American Fern Journal 



duce by spores and are distinguished from other spore 

 plants by having much more highly developed organs, 

 such as stem, leafy sporophyte, roots (with few excep- 

 tions), and vessels for the conduction of water. They 

 are distinguished from the flowering plants by the ab- 

 sence of seed. 



Key to the Families 



A. Plants rooted to the ground though sometimes submerged, often not 

 moss-like, nearly always more than 1 in. long; leaves either not 

 minute or else not 2-lobed. 

 B. Leaves not palmateiy 4-foliolate, not clover-like. 



C. Branches jointed, hollow (except in Equiselum scirpoides), elon- 

 gated; leaves reduced to a sheath-like whorl of bracts at each 

 joint. Equisetaceai Horse-tail Family). 



CC. Branches not jointed, solid, often not elongated or none; leaves 

 not mere sheath-like whorls of bracts. 

 D. Plant a tuft of long grass-like leaves from a somewhat bulbous 

 stem. Isoetaceae (Quillwort Family). 



DD. Leaves not grass-like; stem often elongated. 



E. Leaves }•> in. or less long, entire or merely serrulate, sessile; 

 plant resembling a large moss. 



F. Spores all alike; leafy cylinder H in. or more in diameter, 



if only % in. wide with the stem beneath the surface of 

 the ground. Lycopodiaceae (Club-moss Family). 



FF. Spores of two kinds; leafy cylinder ^ in. or less in dia- 

 meter; stem prostrate. 



Selaoinellaceae (Moss-fern Family)* 

 EE. Leaves 1 or more inches long, lobed to compound (except 

 entire in Ophioglossum), petioled; plant not moss-like. 



G. Sporangia in a spike or panicle which is not green, but is 



apparently a branch of the leaf-stalk of an ordinary 

 foliage leaf. Ophioglossaceae (Adder's-tongue Family). 

 GG. Sporangia on the ordinary green foliage leaves, or else 

 on modified but wholly separate green leaves. 



Polypodiaceae (True Fern Family). 

 BB. Leaves palmateiy 4-foliolate, much resembling a 4-leaved clover. 



Marsiliaceae (Clover-fern Family). 



\A. Plants f re. -floating or merely stranded, moss-like, M~\ inch long; 



leaves minute, 2-lobed. Salviniaceae (Floating-fern Family). 



LYCOPODIACEAE. Club-moss Family. 



Plants perennial, evergreen, somewhat moss-like, erect 

 or creeping, terrestrial, very leafy; stems often elongated, 

 usually freely diehotomously branched. Leaves arranged 

 in 4 to many ranks, many, small, lanceolate, simple- 



