1922] 



PFEIFFER MONOGRAPH OF THE ISOETACEAE 157 



/. echinospora var. muricata Engelm. in Gray, Manual, ed. 5, 

 676. 1867. 



/. echinospora Braunii f. Boottii Clute, Fern Allies, 221, 258. 

 1905. 



7. echinospora Brittoni Cockerell, Muhlenbergia 3: 9. 1907. 



/. muricata Dur. Bull. Soc. Bot. Fr. 11 : 101. 1804. 



/. ambigua A. Br. in Engelm. Trans. St. Louis Acad. Sci. 4: 380. 

 1882. 



Corm 2-lobed; leaves usually 10-35, in robust forms 27-55, 

 8-25 cm. long, or rarely longer, straight or recurved, firm, taper- 

 ing to apex, with rather wide base with membranaceous borders ; 

 stomata present, usually few; peripheral strands none; ligule 

 deltoid; sporangia) oblong, spotted, 4-7 mm. long, with velum 

 1/2 to completely covering it (western forms of U. S. have narrow 

 velum) ; megaspores white, 420-580 (j in diameter, marked with 

 numerous spines ranging from single slender spines to those 

 toothed or even confluent in short ridges; microspores fawn- 

 colored, 23-33 (.1 long, smooth to slightly roughened on surface. 



Distribution: North America. 



Specimens examined: 



Greenland: 60-60 43' N. lat., Southern Greenland ("Tesser- 

 mint"), probably about 1825, Jens Vahl (Mo. Bot. Gard. 

 Herb.); Kingua Neriak, 61 35', July, 1889, Hartz (Gray 

 Herb.). 



Newfoundland : immersed, sandy soil, Channel, 27 July-1 August, 

 1901, Howe & Lang 954 (Gray Herb, and N. Y. Bot. Gard. 

 Herb.); small ponds among Siberian Hills back of Birchy 

 Cove (Curling), region of Humber Arm, Bay of Islands, 11 

 August, 1910, Fernald & Wiegand 2402 (Gray Herb.) ; bar- 

 rens at base of the serpentine table-lands, Bonne Bay, 27 

 August, 1910, Fernald & Wiegand 2405 (Gray Herb.) ; grav- 

 elly brook in bog, Bishop Falls, 29 July, 1911, Fernald & 

 Wiegand 441 1 (Gray Herb.); shallow pools in bog, Bishop 

 Falls, Valley of Exploits River, 29 July, 1911, Fernald & 

 Wiegand 4406 (Mo. Bot. Gard. Herb, and Gray Herb.); 

 shallow pools in the tundra near Quarry ( Lauren tian Area 

 at head of Exploits River System), 23 August, 1911, Fernald 

 & Wiegand 4401 (Gray Herb.) ; deep water near center of 

 middle Birchy Pond (eastern drainage area of Humber 

 River System), Fernald & Wiegand 2400 (Gray Herb.) ; wet 



