148 OUR NATIVE FERNS AND THEIR ALLIES. 



{Butler). The variety in cedar barrens, near Nashville, Ten- 

 nessee (Gattinger). 



ft Velum complete. 



16. I. Nuttallii A. Br. Trunk almost globose, slightly 

 grooved ; leaves 20 60, slender, bright-green, 3' 9' long, with 

 only three peripheral bast-bundles ; sporangia oblong or oval, 

 entirely covered by the velum ; macrospores variable, 0.25 0.50 

 mm. thick, densely covered with minute but rounded warts, or 

 rarely almost smooth; microspores papillose, brown, 0.025 

 0.028 mm. long. (/. opaca Nutt.) Oregon, Washington Terri- 

 tory ; Western Idaho (Geyer), Vancouver Island (Macoun). 



** Trunk trilobed ; velum complete. 



17. I. Suksdorfii Baker. Leaves 12 20, firm, bright- 

 green, very slender, arcuate, deeply channelled along the face, 

 2' 3' long, less than |" wide; sporangia orbicular, 2" long and 

 broad; ligula deltoid ; macrospores grayish-white, faintly granu- 

 lated. W. Klickitat County, Washington Territory (Suksdorf, 

 No. 836). 



