76 University of California P 1(1)1 icatiwis in Botany [Vol.8 



I-'l/fW^yfi acstiMrii, as commonly understood, is a widespread and, 

 to some extent, polymorphous species, yet generally readily recognized 

 in a normal form. It occurs in shallow ditches and pools of brackish 

 water all over tlie world except in the polar regions. It varies con- 

 siderably as to the color and stratification of the sheath as well as in 

 habit. 



Lynghya acstuaril is pr()i)erly a species of tlie tropical (or at least 

 warmer) waters and is an excellent example of how such a species 

 may invade zones of cooler waters, by finding in shallow pools and 

 ditches waters warmed by the sun to the temperature favorable to 

 their growth and reproduction. 



The following forms have been detected on our coast: 



Lyngbya aestuarii f. aeruginosa (Ag.) Wolle 



Plate 1, fig. 16 



Plant mass pale blue-green; sheatlis moderately thin, hyaline. 



Floating in lagoons, salt water. Whidbey Island, Washington, 

 and probably common in similar habitats along the Pacific Coast to 

 the south. 



Wolle, in Wittrock and Nordstedt, Alg. Aq. Dulc, no. 282 ; Setchell 

 and Gardner, Alg. N.W. Amer., 1903, p. 187 ; Gomont, Monogr. des 

 Oscill., 1892, p. 130 (1893, p. 150, Repr.) ; Collins, Holden and Setchell, 

 Phyc. Bor.-Amer. (Exsicc), no. 902. Lynghya aeruginosa Agardli, 

 Syst. Alg., 1824, p. 74. 



Lyngbya aestuarii f. ferruginea Gomont 



Plants forming dense floating masses, of dark or ferruginous color ; 

 sheaths thick, lamellate, deep yellowish brown color. 



Floating in pools, salt marsh, Wliidbey Island, Washington. 



Gomont, Monogr. des Oscill., 1892, p. 130 (1893, p. 150, Repr.) ; 

 Setchell and Gardner, Alg. N.W. Amer., 1903, p. 187. 



Lyngbya aestuarii f. limicola Gomont 



Plants inhabiting moist soil, occasionally inundated, forming 

 rather thin compact strata; filaments closely interwoven and very 

 tortuous. 



Growing on mud in salt marsh, Whidbey Island, Washington. 



Gomont, Monogr. des Oscill., 1892, p. 129 (1893, p. 149, Repr.) ; 

 Setchell and Gardner, Alg. N.W. Amer., 1903, p. 186; Collins, Holden 

 and Setchell, Phyc. Bor.-Amer. (Exsicc), no. 903. 



