Anahaena wisconsinense Prescott 1944, p. 373 

 PL 115, Figs. 3-7; PL 119, Figs. 4-8 



Trichomes planktonic; straight or slightly flexuous; solitary or 

 (more often) aggregated in parallel fashion to form small, loose, 

 flake-like bundles; without a sheath; not tapering at the apices. 

 Cells quadrate to cylindrical; constricted at the cross walls; 3.6-4/a 

 in diameter, 3.6-10.8/a long; with large pseudovacuoles. Heterocysts 

 spherical or compressed-globose, 3.6-4.2/i, in diameter; only 1 in 

 each trichome, centrally located. Gonidia elliptic-ovate to broadly 

 oval, 7.2-8;u in diameter, 10-13;u, long; beginning their development 

 as a series of 3 enlarged vegetative cells, of which usually only 1 

 matures, so that each trichome has but a single gonidium (if more 

 than 1, the gonidia in pairs); remote from the heterocysts. 



This plant is remindful of Aphanizomenon flos-aquae. It should be 

 compared with Anahaena aphanizomenoides Forti, from which it 

 differs in its smaller size throughout, in the shape of the gonidia, 

 and in the location of the gonidia ( remote from, rather than adjacent 

 to, the heterocysts ) . 



Both euplanktonic and tychoplanktonic. Wis. 



ANABAENOPSIS (Wolosz.) Miller 1923, p. 125 

 Trichomes planktonic; short and coiled, with a heterocyst at either 

 end. Cells elongate-ovoid to subcylindric. Akinetes intercalary, re- 

 mote from the heterocysts. 



Anabaenopsis Elenkinii Miller 1923, p. 125 

 PL 131, Fig. 4 



Trichomes composed of ellipsoid or elongate-ovoid cells which 

 contain pseudovacuoles. Heterocysts spherical, 4.6-6.7/x in diameter. 

 Akinetes broadly ovoid, 8.3-10.5fi in diameter, 9.3-12/^, long; some- 

 times nearly spherical, 8.3-10.7/a in diameter. Cells 4.6-5.7/a in 

 diameter. 



Cheboygan County, Michigan. 



NOSTOC Vaucher 1903, p. 203 

 Membranous or globular or irregularly lobed colony of tangled, 

 uniseriate unbranched trichomes of globose and bead-like, barrel- 

 shaped, or cylindrical cells, inclosed in copious, thick mucilage 

 which ( in many species ) outwardly forms a firm integument, giving 

 the colony a fixed and definite shape; individual sheaths of the 

 trichome confluent with the colonial mucilage; trichomes without 

 basal-distal differentiation, made up of vegetative cells, frequent 



[520] 



