46 



THE FLORA OF NEBRASKA. 



Spirogyra iniiata (Vauch.) Rabh. Hand. II., 2, 120. 

 Conjugata inflata Vauch. Hist. Conf. 68. 1803. 



Cespitose bright green, vegetative filaments 14-15 ft in diam., 3-8 times 

 longer; spiral single, making 3-8 turns in each cell; zygogonium much 

 inflated; zygospore fusiform-elliptical, 30-36 ft in diam., twice as long. 

 Lincoln, Thedford. PI. VIII., Fig. 6, a, b. 

 Spirogyra qnaclrata (Hass.) P. Petit Bull. Soc. Bot. Franc. 41. 1874. 

 Zygnema quadratum Hass. Brit. F. W. Alg. 157. 1845. 



Usually scattered among other algae, rarely aggregated in light green masses; 

 vegetative filaments 24-27 ft in diam.; cells 3-9 times as long as the di- 

 ameter; spirals rarely 2, making 1^-5 turns in each cell; zygospore some- 

 what quadrate, flattened in the middle, elliptical or fusiform, brown at 

 maturity, 28-40 ft in diam. ; copulation often lateral. 

 Ponds, Lincoln. PI. IX. Fig. 2 and 2 a. 

 Spirogyra grevilleana (Hass.) Kuetz. Sp. Alg. 438. 1849. 

 Zygnema grevilleanum Hass. Brit. F. W. Alg. 149. 1845. 



Light green, vegetative cells 25-33 ft in diam., 3-10 times as long; spiral single, 

 rarely double, making 4-7 turns; zygospore oval, brownish yellow, 30-36 ft 

 in diam., 2-2)^ times as long. 

 Lincoln. PI. VIII., Figs. 5 and 5 a. 



* * Membrane of zygospore punctate. 



Spirogyra calospora Cleve Svensk Zygnem. 26. 1863. 



Vegetative cells 30-40 ft in diam., 6-12 times as long, spiral single, making 4-5 

 turns; zygogonium slightly or not at all swollen; zygospore ellipitical, 

 rounded at the ends, yellow at maturity, 40-42 ft in diam., 2-3 times as 

 long. 



Streams, Lincoln. PI. VIII., Fig. 8. 



Two or more spirals in each cell. 



Spirogyra insignia (Hass.) Kuetz. Sp. Alg. 438. 1849. 

 Zygnema insigne Hass. Brit. F. W. Alg. 440. 1845. 



Vegetative cells 36-42 ft in diam., 4-12 times longer than wide, 3 spirals, rarely 

 2, making 1-3 turns; zygogonium much swollen; zygospore elliptical, 28 ft 

 in diam., twice as long. 



Var.— brannii Rabh. Fl. Eur. Alg. Ill, 235. 1868.— Cells 8-12 times as long as broad; 

 2 spirals. 

 Lincoln. PI. IX. Figs. 4 and 4 a. 



Section H.— Cell-membrane not folded in at the ends. 

 Oue spiral in each cell. 



* Membrane of the zygospore smooth. 

 Spirogyra mirabilis (Hass.) Kuetz. 1. c. 



Zygnema mirabile Hass. Brit. F. W. Alg. 156. 1845. 



Cespitose; vegetative cells 24-27 ft in diam., 4-10 times as long, spirals making 

 4 7 turns in each cell; zygogonium inflated; conjugation often lateral; 

 zygospore 24-26 ft in diam., \-\ x A times as long. 

 Ponds, etc., Lincoln. PI. IX., Figs. 3 and 3 a. 



