1922] 



PFEIFFER MONOGRAPH OF THE ISOETACEAE 185 



Herb.) ; Kingston, September, 1S97, Eaton 942 (Mo. Bot. 



Card. Herb.). 

 Massachusetts: Uxbridge, 1845, Robbws 10 (Mo. Bot. Gard. 



Herb.) ; Watson's Pond, Taunton, 15 September, 1903, Ea- 

 ton (Mo. Bot. Gard. Herb.) ; Leach's Pond (Wilbor's Pond), 



(Mass.?), September, 1906, Eaton (Me. Bot. Gard. Herb.); 



Uxbridge, 31 August, 1907, Eaton (Mo. Bot. Gard. Herb.); 



rare, muddy shores, pool in Peabody Cemetery, 10 October, 



1915, Andrews (Gray Herb.). 

 Connecticut: half submerged on shore of Chapman's Pond, Gro- 



ton, 30 August, 1896, Graves 144 (Mo. Bot. Gard. Herb.) ; 



mill-race in Mill River, Fairfield, 19 July, 1905, Eames 5294 



(Gray Herb.). 

 New Jersey: Pt. Pleasant, September, 1899, Best (Mo. Bot. 



Gard. Herb.) ; Pt. Pleasant, 4 July, 1899, Best & Crawford 



(Mo. Bot. Gard. Herb.). 



The species and the variety are very close; the distinction is 

 based chiefly on the tendency to larger size in the variety which 

 is evinced in more and longer leaves. There is also an inclina- 

 tion toward larger microspores, though the ranges overlap suf- 

 ficiently so that this too cannot be used absolutely. The Ux- 

 bridge material of Robbins is of the intermediate sort, with 

 somewhat bigger microspores, but plant size according well with 

 the general range of the species. 



49. 1. Pringlei Underw. Zoe 1 : 98. 1890. 



Corm 2-lobed; leaves 4^20, 16-30 cm. long, firm, fine, taper- 

 ing, with membranaceous margin only briefly extended (1 cm.) 

 above level of the sporangium; stomata abundant; peripheral 

 strands numerous, 6 conspicuous and 6-10 accessory groups; 

 ligule triangular, short and wide; sporangium large, up to 10-12 

 mm. in length in large individuals, partly covered by narrow 

 velum ; megaspores chalky white when dry, tan when moist, 460- 

 550 M in diameter, rarely 650 \i, marked with high tubercles, oc- 

 casionally extended into brief rounded crests; commissural 

 ridges irregular in outline ; microspores fawn-colored, 35-42 n 

 long, sometimes showing tendency toward winged condition. 



Distribution : Mexico. 



Specimens examined : 

 Mexico: in grassy springy places near Guadalajara, State of 



