358 Broadhurst: Struthiopteris in North America 



Most of the petioled species are very large, and complete 

 sterile and fertile leaves are not always found in the same herba- 

 rium number; therefore, in this paper the comparative height is 

 often omitted, though it may be more or less accurately deduced 

 from the figures given for the length of the sterile and the fertile 

 fronds, respectively. 



Key to the petioled species 



B. Sterile pinnae (at least the lower ones) petioled;* rhizome scales rigid 

 or flaccid; pinnae more or less scaly; indusium irregularly 

 lacerate to fimbriate with age 

 Rhizome scales very slender, rigidly erect, with dark centers; 

 vestigial pinnaef present; margins entire; coriaceous 

 (rigid-herbaceous in S. Underwoodiana) . 

 Sterile lamina very abruptly reduced at the base (type A, 

 with vestigial pinnae) ; pinnae crowded to overlapping, 

 elliptical, obtuse; dried pinnae rolled and rufous below; 

 margins revolute. 16. S. rufa. 



Sterile lamina abruptly reduced at the base (type D, 

 with vestigial pinnae except in 5. Shaferi) ; pin- 

 nae never crowded or overlapping, narrowly ob- 

 long to linear, acute to acuminate; dried pinnae not 

 rolled, gray-green to yellowish brown or brown 

 below; margins} not revolute. 

 Apex of the sterile lamina gradually reduced; 

 upper sterile pinnae not conspicuously dilated 

 both ways at the base, the base of the lower ones 

 cuneate, petioled; deciduously araneous below; 

 vein spaces 18-20 to 1 cm.; rachis scales mixed 



with white, fibrillose ones. 25. 5. Werckleana. 

 Apex of the sterile lamina not reduced; upper sterile 

 pinnae conspicuously dilated both ways at 

 their base, the bases of the lower ones barely 

 petioled, rounded; not araneous below; vein 

 spaces 10-16 to 1 cm.; rachis without white, 

 fibrillose scales. 

 Lower sterile pinnae prominently dilated or 

 auricled at the base; stipes short, 3-10 cm. 

 long, without vestigial pinnae; costae not 

 flattened on the under side; vein spaces 15 or 

 16 to 1 cm.; indusium light-colored, regularly 

 lacerate to its base, concavely hollowed on 

 the sides of the lacerations. IQ . 5. Shaferi. 



* 5. Underwoodiana and 5. Shaferi, the only forms not distinctly petioled, have 

 rigid rhizome scales which are never found in the species in the preceding division, 

 t Except in i>. Shaferi. 



t Incompletely and very narrowly so in 5. Shaferi, which is peculiarly glandular; 

 see description. 



