1922] 



PFEIFFER — MONOGRAPH OF THE ISOETACEAE 175 



1S07, Rosendahl 2050 (Mo. Bot. Gard. Herb., Gray Herb., U. 



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

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



Rainier, 23 August, 11)01, 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 u 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. I. truncata Clute, Fern Allies, 222-223, 260. 1005. 



/. 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, 4-0 mm. 



arked profusely with brown patches of sclerenchyma 



about VatV^ of 



white 



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

 blunt spines ; microspores 27-33 \a 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, /. Macoun (Mo. Bot. Gard. 



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

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



Doubtful: Coville & Kearney 386, New Metlakatla, Annette 



Isl., Alaska, 4 June, 181)9. 



In the spinulose megaspores there is as wide a variation in 



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



with a marked tendency toward elongated, densely crowded, 



rather tuberculate structures. For the close arrangement the 



