SPIROGYRA 191 



cylindric or slightly inflated; zygospores lenticular, '^y-Sin x 45-60/1; 

 median spore wall brown, smooth; aplanospores similar but smaller. 

 (PL XXXI, Figs. 14-15.) 



United States: Very abundant in late spring and summer throughout 

 the northcentral states; also reported from Washington and Texas; and 

 from the eastern states. New England to South Carolina. 



Europe; China; South Africa; Brazil; Uruguay. 



This is a complex group of elementary forms, differing in dimensions 

 and numbers of chromatophores. However, among the many collections I 

 have examined, the overlapping of form characteristics is so continuous from 

 the smaller to the larger specimens that there seem to be no good bases for 

 separation as varieties and forms. Czurda (1932, p. 204) discusses smaller 

 and larger forms. Conard (Beih. Bot. Zentralbl. 55, p. 184, 1936) proposed 

 to remove certain of the species having lenticular spores from the genus 

 Spirogyra under the generic name Degagnya. This proposal would require 

 a restudy of all species of Zygnemataceae, since he introduces new criteria 

 for the separation of genera. The species Conard designates as D. majuscida 

 Conard is certainly not our species S. majuscula Kiitzing. 



In 1884 Professor C. E. Bessey reported finding this species conjugating 

 with S. protecta. Conjugation occurred in both directions and the zygo- 

 spores formed were similar to those of the female filament. 



159. Spirogyra submaxima Transeau 1914. Amer. Jour. Bot. 1, 



p. 295, PL 27, Figs. 3-4. 



Vegetative cells 70-110/1 x 100-300/1, with plane end walls; 8 to 9 

 chromatophores making .1 to i turn; conjugation scalariform; tubes 

 formed by both gametangia; fertile cells cylindric, enlarged, or slightly 

 inflated; zygospores lenticular, 70-110/1 x 50-75/1; median spore wall 

 brown, smooth. 



United States: Missouri and Mississippi eastward to Massachusetts. 



China; India. 



Found hybridizing with S. maxima at Charleston, Illinois. 



160. Spirogyra glabra Czurda 1932. Siisswasserflora Mitteleu- 



ropa. 9, p. 206, Fig. 222. 



Vegetative cells 145-153 /i x 120-220/1, with plane end walls; 7 chro- 

 matophores; conjugation scalariform; tubes formed by both gam- 

 etangia; fertile cells cylindric; zygospores lenticular, about 120/1 x 170/1; 

 outer spore wall about lo/i thick, colorless; median spore wall about 

 20/1 thick, yellow-brown, smooth. (PL XXXI, Fig. 16,) 



Austria, Vienna. 



161. Spirogyra bellis (Hassall) Cleve 1868. Nova Acta Reg. Soc. 



Sci. Upsali. Ser. 3, 6, p. 18, PL 3, Figs. 2-5. 

 Vegetative cells 65-80/1 x 90-350/1, with plane end walls; 5 to 6 



