Broadhurst: Struthiopteris in North America 359 



Lower sterile pinnae not dilated or auricled at 

 the base; stipes 18-36 cm. long, with vestigial 

 pinnae; costae flattened on the under side; 

 vein spaces 10-13 to 1 cm.; indusium dark, 

 only occasionally lacerate to the base, not 

 concavely hollowed on the sides of the lacer- 

 ations. 21. 5. Underwoodiana. 

 Rhizome scales broad, flaccid, without dark centers; ves- 

 tigial pinnae* lacking; margins more or less serrate; 

 membranous to rigid-herbaceous. t 

 Sterile pinnae with rounded to tapering bases. 



Pinnae 2-5-jugate, 4-7.5 cm. long, ovate to ovate- 

 lanceolate, with an acute apex. 13. S. danaeacea. 

 Pinnae 8-25-jugate, 9-26 cm. long, lanceolate to 

 linear, with an acuminate apex. 

 Margins conspicuously and irregularly erose; 

 stipes red-purple; lamina not reduced at the 

 apex. 22. S. varians. 

 Margins entire to finely serrate; stipes shining 

 straw-colored to dull, pale brown; lamina re- 

 duced at the apex in all except the smallest 

 forms. 17. 5. Schiedeana. 

 Sterile pinnae with cordate, or rarely subcordate, bases. 

 Stipes with vestigial pinnae, closely covered with 

 peculiar, appressed, amorphous scales, ordinary 

 scales lacking; viviparous near the apex of the 

 rachis; lamina not reduced at the apex. 24. S. vivipara. 

 Stipes without vestigial pinnae, ordinary scales pres- 

 ent, with or without fibrillose or somewhat 

 formless appressed ones; not viviparous; 

 lamina reduced at the apex (except in the 

 smaller ,S. striata specimens). 

 With red-purple to black stipes; pinnae with 

 an acute (or obtuse?) apex; lower fertile 

 pinnae usually with spurlike protuberances. 23. 5. violacea. 

 With straw-colored to chestnut stipes; pinnae 

 with an acuminate apex; lower fertile 

 pinnae usually without spurlike pro- 

 tuberances. 

 Margins never revolute, but sharply, finely, 

 and regularly cartilaginously serrate 

 throughout. 14. 5. falciformis. 

 Margins irregularly or fully revolute, defi- 

 nitely serrate at the apex only. 

 Stipe scales narrow, short, 2-6 mm. 

 long, projecting; appressed finer ones 

 inconspicuous. 10. S. chiriquana. 



* Except in 5. vivipara 

 t Exc 

 5. striata. 



* Except in 5. vivipara. 



f Except in the smaller specimens of 5. violacea and one St. Vincent specimen of 



triata. 



