1922] 



PFEIFFER MONOGRAPH OF THE ISOETACEAE 175 



1907, Rosendahl 2050 (Mo. Bot. Card. Herb., Gray Herb., U. 



S. Nat. Herb., and Univ. Minn. Herb.). 

 Washington: lake 2 ft. deep (volcanic ash), Mirror Lake, Mt. 



Rainier, 23 August, 1901, Flett 1930 (Mo. Bot. Gard. Herb. 



and N. Y. Bot. Gard. Herb.). 



It seems possible that this is but a form of /. Braunii Dur. 

 growing under rather hard conditions. The distinguishing 

 features are the large microspores with their papillose markings, 

 in contrast to the usual smooth /. Braunii spores of 35 n or less; 

 the more numerous stomata, which are probably due to greater 

 exposure ; and the narrow velum, a feature which is shared, how- 

 ever, by most western specimens of /. Braunii. 



43. 1. truncata Clute, Fern Allies, 222-223, 260. 1905. 

 /. echinospora var. truncata Eaton in Gilbert, List N. Am. 

 Pterid. 10: 27. 1901. 



Corm 2-lobed ; leaves 20-40, 6-13 cm. long, stout, rather rigid, 

 finely tapering, with almost setaceous apex and wide membra- 

 naceous margin at base; stomata numerous; peripheral strands 

 lacking; ligule short- triangular ; sporangium oblong, 4-6 mm. 

 long, marked profusely with brown patches of sclerenchyma cells ; 

 velum covering about Vr-Mi f sporangium; megaspores white, 

 430-520 n, rarely 680 p, in diameter, marked with numerous 

 blunt spines ; microspores 27-33 p long, papillose. 

 Distribution: Alaska, Vancouver Island. 

 Specimens examined: 



Alaska: Kodiak, 20 July, 1899, Coville & Kearney Jr. 2336 & 

 2337 (Mo. Bot. Gard. Herb, and U. S. Nat. Herb.), TYPE; 

 Kodiak, 20 July, 1899, Fernow 2640 (Mo. Bot. Gard. 

 Herb.). 



Vancouver Island: Sproat Lake, J. Macoun (Mo. Bot. Gard. 

 Herb.) ; Sproat Lake, fresh water, 13 August, 1887, J. Ma- 

 coun 5 (N. Y. Bot. Gard. Herb.). 

 Doubtful: Coville & Kearney 386, New Metlakatla, Annette 



Isl., Alaska, 4 June, 1899. 



In the spinulose megaspores there is as wide a variation in 

 size, number, and arrangement of spines as in I. Braunii Dur. 

 with a marked tendency toward elongated, densely crowded, 

 rather tuberculate structures. For the close arrangement the 



