164 Minnesota Algae 



1 Trichomes 3-3.5 mic. in diameter, especially cylindrical; gonidia S 



mic. in diameter, 7 mic. in length; wall of gonidium smooth 



N. verrucosum 



2 Trichomes 2-3 mic. in diameter, distinctly torulose; gonidia 3-4 mic. 



in diameter, 5-6 mic. in length; wall of gonidium smooth, brown 



N. amplissimutn 



3 Filaments radiating from the center, flexuous, very densely twisted 



and entangled near the surface; trichomes 4-4.5 mic. in diameter; 

 gonidia 4-5 mic. in diameter, 7-8 mic. in length, oval; wall of go- 

 nidium smooth, yellowish N. parmelioides 



309. Nostoc cuticulare (Brebisson) Bornet and Flahault. Revision des 



Nostocacees heterocystees contenues dans des principaux herbiers 

 de France. Ann. Sci. Nat. Bot. VII. 7: 187. 1888. De Toni. Syll. 

 Algar. s: 387. 1907. 

 Collins, Holden and Setchell. Phyc. Bor.-Am. Fasc. 7. no. 308. 1897. 

 Plant mass flattened, adnate, forming thin, orbicular, confluent, dark 

 blue-green patches; filaments closely entangled, here and there forming 

 denser clusters; sheaths more or less distinct, wide, gelatinous, trans- 

 parent; trichomes 3.8-4 mic. in diameter, torulose; cells barrel-shaped, equal 

 to or a little longer than the diameter; heterocysts barrel-shaped, equal to 

 or a little larger than the cells; cell contents blue-green. 



New York. On leaves of Potamogeton. Ithaca. (Atkinson). 



310. Nostoc punctiforme (Kuetzing) Harlot. Le Genre Polycoccus Kuet- 



zing. Morot. Journ. de Bot. 5: 29. i8gi. Reinke. Zwei parasitische 



Algen. Bot. Zeit. 37: 473. pi. 6. f. 1-5. 1879. (Anabaena cy- 



cadearum Reinke). Bornet and Flahault. Revis. des Nostoc. 



Ann. Sci. Nat. Bot' VII. 7: 189. 1888. (N. hederulae Menegh.). 



Sauvageau. Sur le Nostoc punctiforme. Ann. Sci. Nat. Bot. VIII. 



3: 367. pi. 17. 1897. Pampaloni. II Nostoc punctiforme nei suoi rap- 



porti coi Tubercoli Radicali delle Cicadee. Nuovo Giornale Bot. 



Ital. N. S. 8: 6z6. pi. 5. 1901. De Toni. Syll. Algar. 5: 388. 1907. 



Schneider. Mutualistic Symbiosis of Algae and Bacteria with Cycas 



revoluta. Bot. Gaz. 19: 25. pi. 3, 4. 1894. Tilden. American Algae. Cent. 



II. no. 171. 1896; List of Fresh-Water Algae collected in Minnesota during 



1896 and 1897. Minn. Bot. Studies. 2: 27. 1898. Life. The Tuber-like 



Rootlets of Cycas revoluta. Bot. Gaz. 31: 265. 1901. Lemmermann. Al- 



genfl. Sandwich. -Inseln. Bot. Jahrb. 34: 622. 1905. Buchanan. Notes on 



the Algae of Iowa. Proc. Iowa Acad. Sci. 14: 12. 1908. 



Plate VI. fig. 35-37- 



Colonies small, somewhat globose, scattered or confluent, adnate; 

 filaments flexuous, very densely entangled; sheaths close, transparent, mu- 

 cous; trichomes 3-4 mic. in diameter; cells depressed spherical or elliptical; 

 heterocysts 4-6.5 mic. in diameter, transparent; gonidia somewhat spherical 

 or oblong, 5-6 mic. in diameter, 5-8 mic. in length, with thick, smooth, 

 outer membrane; cell contents finely granular, light olive green. 



Minnesota. In roots of Cycas revoluta. University Plant House, 



