Broadhurst: Struthiopteris in North America 2G1 



STRUTHIOPTERIS (Hall.) Scop. 



Fronds dimorphous (otherwise resembling Blechnum), usually 

 pinnatifid or once pinnate; veins free, simple or usually once 

 forked, usually not reaching the margin; sori linear and intra- 

 marginal (not costal as in Blechnum) ; indusium intramarginal in 

 attachment,? at maturity opening toward the midrib, and then 

 either (i) entire and not reflexed or (2) more or less lacerate or 

 fimbriate and reflexed. 



Key to the 11011-petioled species t 



A. Sterile pinnae never petioled, the wholly adnate base the widest part 



of the pinna; rhizome scales never rigid; pinnae lacking 



scales; indusium not lacerate with age 



Plants epiphytic; rhizome wide-creeping; rhizome scales and 

 basal stipe scales usually with a black median line (wholly 

 lacking in 5. Plumieri); stipes scattered, the fertile ones 

 straw-colored or bicolored with dull brown or blackish; 

 mature lamina not punctate by transmitted light; fertile 

 pinnae not conspicuously dilated at their bases. 

 Lamina broadly oblong, very abruptly reduced at the base 

 (type A, J with vestigial pinnae); pinnae 22-28-jugate, 16- 

 18 cm. long, straight or nearly so, the middle ones always 

 straight. *■ •^- ensiformis. 



Lamina linear or very narrowly oblong to broadly lance- 

 olate, gradually to abruptly reduced at the base 

 (type G to D, with vestigial pinnae in D only) ; pinnae 

 25-75-jugate, 2.5-16 cm. long, slightly curved to 

 falcate, the middle ones always falcate. 

 Rhizome scales usually with a black median line; lamina 

 linear, narrowly oblong, or lanceolate, 4-17 times as 

 long as broad, usually very gradually reduced at the 

 base (type G to F, rarely E); leaf tissue rigid- 

 herbaceous; pinnae usually contiguous. 7- -5. poly podio ides. 



* The intramarginal character of the indusium is obscured in many of the pinnate 

 species by the thickened edges of the pinnae, due to the more or less glandular 

 thickening of the vein apices. In the sterile pinnae these thickenings may result 

 in dark spots, slight swellings, circular cartilaginous areas or depressions, or occasion- 

 ally in more or less detachable scalelike elevations. 



t The species having petioled sterile pinnae will be discussed in a later number 

 of the Bulletin of the Torrey Botanical Club. The sterile fronds of the 

 non-petioled species are cut to the rachis, but the bases of the pinnae are wholly ad- 

 nate, and except in a few specimens of S. ensiformis, the base is always the widest 

 part of the pinna. Fee and others classify these as pinnatiftd. Petiole instead of 

 petiolule is used throughout when referring to the pinnae. 



t See figure i, which gives several diagrams illustrating the variation in the 

 bases of the laminae. 



