1922] 



PFEIFFER — MONOGRAPH OF THE ISOETACEAE 139 



36: 325. 1883. 



Corm 2-lobed; leaves 6-100, coarse, erect, form abruptly 

 pointed, triangular in cross-section; stomata and peripheral 

 strands lacking; sporangia oblong, truncate, hardly spotted; 

 velum lacking; megaspores inconspicuously tuberculate above, 

 distinctly in center of basal part; microspores smooth, brown or 

 white. 



Distribution: South America, Peru. 



This description is derived from a combination of characters 

 given by A. Braun and Motelay & Vendryes. 



34. I. Howellii Engelm. Trans. St. Louis Acad. Sci. 4: 385. 

 1882; Underwood, Native Ferns and Fern Allies, 124. 1882; 

 Eaton, Fern Bull. 8: 32-33. 1900; Piper and Beattie, Fl. Wash. 

 8. 1914. 



/. nuda Engelm. Trans. St. Louis Acad. Sci. 4: 385. 1882. 



/. Underwoodi Hend. Bot. Gaz. 23: 124. 1897. 



/. melanopoda var. californica A. A. Eaton in Gilbert, List 

 N.Am. Pterid. 10: 27. 1901. 



Corm 2-lobed; leaves 10-30, rarely 50, 5-24 cm. long, bright 

 green, erect or slightly outspread, slender (less so in emersed 

 forms), with wide membranaceous margin extending 1-5 cm. 

 above sporangium level, sometimes abruptly narrowed ; stomata 

 numerous; peripheral strands usually 4, sometimes 1 or more 

 lacking; ligule narrow, elongated triangular; sporangia orbicular 

 to oblong, 3-6, rarely 8, mm. long, frequently brown-spotted, 

 partially covered by velum, up to 1/3; megaspores white, 420- 

 520 m in diameter, more or less obscurely marked with simple 

 tubercles to short crests, isolated or anastomosing, sometimes 

 crowded, sometimes distant; microspores 25-33 p long, chiefly 

 27 m, smoothish to short spinulose. 



Distribution: W. Montana, Idaho, Washington, Oregon, Cali- 

 fornia. 



Specimens examined: 

 Montana: 3000 ft. alt., Bigfork, Flathead Co., 14 August, 1909, 



Jones (Mo. Bot. Gard. Herb.) ; border of Swan Lake, 15 



August, 1901, Umbach (U. S. Nat. Herb.). 

 Idaho: in w r et places along Paradise Creek, Moscow, 11 June, 



1S05, Henderson 2891+ (U. S. Nat. Herb.) ; wet ground about 



pools, Paradise Creek, Moscow, without date, Henderson 



