SfiLAGINELLACfi^. 699 



covered by the velum, the free part pale and unspotted ; botli kinds of spores 

 the largest of our species; macrospores (0.32-0.38" wide) covered with short 

 and twined crested ridges, which often anastomose ; nucrospores (0.017 - 0.020" 

 lono) smooth. — Mountain lakes, Penn., N. Y., and New Eug. to Lake Supe- 

 rior, and northward, often with n. 3. (Eu. ) 



2. I. Tuckermani, Brauu. Leaves (10-30, 2 -3' long) very slender, 

 awl-shaped, olive-green, the outer recurved ; sporangium ovoid or circular, the 

 upper third covered by the velum, the free part sometimes brownish-spotted ; 

 macrospores (0.22-0.28" wide) on the upper segments covered with parallel 

 and anastomosing ridges, the lower half reticulated; microspores (0.013- 

 0.015" long) smooth or very delicately papillose. — Mystic and other ponds 

 near Boston, together with the next [Tackernuin, W. Boott). 



3. I. echinospora, Durieu. Leaves slender, awl-shaped ; sporangium 

 ovoid or circular; macrospores (0.20-0.25" wide) beset all over with small 

 entire and obtuse or slightly forked spinules. (Eu.) — In this E^uropean form, 

 the leaves are very slenderly attenuated (3-4' long), the upper margin of the 

 sporangium only is covered with the narrow velum, the free part is unspotted, 

 and the slightly papillose microspores are larger (0.015-0.016" long). 



Var. Braunii, Engelm. Leaves (15-30 in number, 3-6' long) dark and 

 often olive-green, straight or commonly recurved, half or two thirds of the 

 sporangium covei-ed by the velum, the free part often with light brown spots ; 

 macrospores as in the type ; microspores smaller (0.013-0.014" long), smooth. 

 (I. Braunii, Durieu.) — Ponds and lakes. New Eng. to N. Y., Penn., Mich., and 

 northward, often wdth the two preceding. — Frequently wdth a few stomata, 

 especially in Niagara specimens. 



Var. roblista, Engelm. Stouter; leaves (25-70, 5-8' long) witli abun- 

 dant stomata all over their surface ; velum covering about one half of the large 

 spotted sporangium ; macrospores 0.18 - 0.27" wide. — Lake Champlaiu, north 

 end of Isle La Motte (Pringle). 



Var. muricata, Engelm. Leaves (15-30, 6- 10' long) straight or flac- 

 cid, bright green ; about one half of the almost circular sporangium covered by 

 the velum, unspotted ; macrospores (0.22 - 0.27" wide) with shorter and blunter 

 spinules; microspores as in the last variety, or rarely spinulose. (I. muricata, 

 Durieu.) — In some ponds north of Boston ( W. Boott). 



Var. Boottii, Engelm. Leaves (12-20, 4-5' high) awd-shaped, stiffly 

 erect, bright green, with stomata; SDorangium as in the last; macrospores as 

 in the type, but a little smaller and with very slender spinules. (I. Boottii, 

 Braun, in litt.) — Pond in Woburn, near Boston, partly out of water ( W. Boott). 

 * * Growing parti ij out of water, either bi/ the pond drying up or by the receding 

 of the ebb tide ; leaves with stomata, and in n. 6 and 7 with four or more 

 peripherical bast-bundles. 



4. I. saccharata, Engelm. Leaves (10- 15, 2-3' long) slender, olive- 

 green, curved ; sporangium small, ovoid, only the upper edge covered by the 

 velum, nearly unspotted; macrospores (0.20-0.22" wide) minutely tubercu- 

 late; microspores (0 012" long) papillose. — On Wicomico and Nauticoke 

 Kivers, eastern shore of Maryland, between high and low tide (Canby). 



5. I. riparia, Engelm. Leaves (15-30, 4-8' long) slender, deep green, 

 erect ; sporangium mostly oblong, upper margin to one third covered by the 



