72 



The genus may be subdivided as follows : 



Lamina deltoid-ovate or cordate, base auriculate or truncate ; rhizome globose, 

 5-10 mm. thick ; commonstalk short, hypogean ; fronds two to four, rarely soli- 

 tary ; spike short and stout. (Southern States, Mexico and South America.") 



I. O. crotalophoroides Walt.* 



Lamina lanceolate or spatulate to ovate, rarely broader, base acute, obtuse or 



rounded. 



Plants normally small, usually less than 9 cm. high (1.5-11.5) ; fronds two or 



three, rarely solitary; commonstalk hypogean, usually less than \ the 



height of the plant. 



Rhizome very small, short-cylindric to globose, 2-5 mm. long, 1. 8-5 mm. 



thick, lamina usually plane and horizontal, \-\ the height of the plant ; 



median vein emitting one or two branches, areolae mostly small and 



divergent; spores 0.030-0.040 mm. thick. (Southern States and Cuba. ) 



2. O. tene7-uin Mett. 



Rhizome larger, long-cylindric, 2-17 mm. long, 2-3 mm. thick, lamina 



usually folded and upwardly inclined, \-\ the height of the plant; 



median vein simple except for secondary connecting veinlets, areolae 



mostly larger and parallel; spores 0.040-0.050 mm. thick. (California 



and Mexico. ) 3. O. californicum Prantl. 



Plants larger, usually more than 12 cm. high (6-40) ; fronds usually solitary; 



commonstalk \ or more epigean, \-\ the height of the plant. 



Lamina lanceolate, spatulate, elliptic, oblong or ovate, apex rounded or 



sometimes acute, not apiculate ; spores reticulately marked with thin 



ridges, more or less verru cose. 



Plants usually more than 15 cm. high ; lamina variable in shape ; 



commonstalk usually \ the height of the plant or more, mostly 



epigean. (Usually in wet boggy ground, Northeastern North America, 



Europe and Asia ; also in Mexico ?) 4. C. vulgatuvi L. 



Plants mostly less than 15 cm. high ; lamina lanceolate or elliptic ; 



commonstalk about \ the height of the plant, about ^ hypogean. (In 



sand, New Jersey, New York and New Hampshire.) 



5. 0. a7-enarium E. G. Britt. 

 Lamina elliptic or rarely ovate, usually acute, apiculate ; spores merely 

 finely pitted, faintly verrucose. (Virginia and Indiana to Mexico.) 



6. O. Enzehnanni Prantl. 



Prantl, in his monograph, in which he treats the genus from a 

 world-wide point of view, divides what he considers to be Euophio- 

 glossuni into two groups of species according to the branching or 

 non-branching of the mid-vein of the lamina, one of the charac- 

 ters used here to distinguish 0. teiicnini from O. californicum. 

 In a general treatment, it may be necessary to make use of this 



* O. reticulatum L. of tropical regions in general, is like O. crotalophoroides in 

 the shape of the lamina, but differs in its greater size, usually solitary fronds, and in 

 having a long, mostly epigean commonstalk, and a cylindric rhizome. 



