148 OUR NATIVE FERNS AND THEIR ALLIES. 



{Bitflcr), near St. Louis, Missouri {Eggcri). The variety in 

 cedar barrens, near Nashville, Tennessee {Gaitinger). 



ft Vcliun 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 ; West- 

 ern Idaho {Geyer^, Vancouver Island {Maconti). 



** Trunk trilobed ; veluin complete . 



17. I. Suksdorfil 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 {Suksdorf, No. 836), 

 California {Brandegee). 



