360 Broadhurst: Struthiopteris in North America 



Stipe scales broad, 1-2 cm. long, flac- 

 cid and lying more or less 

 crumpled along the stipe; ap- 

 pressed somewhat formless ones 

 present and numerous in most 

 species. 

 Sterile pinnae mainly straight ; lam- 

 ina usually 1.5 (rarely 2) 

 times as long as wide; pin- 

 nae 6-24-jugate; lower sur- 

 face with definitely raised 

 veins; margins revolute. 

 Pinnae 20-24-jugate, the apex 

 acuminate, the base subcor- 

 date; lower surface not 



araneous. 12. 5. coslaricensis. 



Pinnae 6-23-jugate (averag- 

 ing io-i8-jugate), the apex 

 abruptly acuminate, the 

 base fully cordate; lower 

 surface usually finely ara- 

 neous. 20. 5. striata. 

 Sterile pinnae mainly falcate; lam- 

 ina 2-4 times as long as 

 broad; pinnae 21-70-ju- 

 gate; veins not raised below 

 (except irregularly so in 

 5'. Chrislli) ; margins rarely 

 fully revolute.* 

 Sterile stipes chestnut ; veins 

 more or less raised below; 

 fertile pinnae occasionally 

 with spurlike protuber- 

 ances. 11. 5. Christii. 

 Sterile stipes straw-colored to 

 brownish; veins not 

 raised below; fertile 

 pinnae without spur- 

 like protuberances. 

 Sterile pinnae 20-40- 

 jugate; fertile pinnae 

 without a glandular, 

 basal enlargement of 

 the petiole. 15. 5. lineala. 

 Sterile pinnae 60-70 -ju- 

 gate ; fertile pinnae with 

 a glandular, basal en- 

 largement of the pet- 

 iole. 18. S. sessilifolia. 



* Except possibly in 5. sessilifolia; the condition of the type specimen seen makes 

 it difficult to determine this. 



