52 University of California rtihJications in Botany [Vol.8 



Suborder 1. IIOMOCYSTINEAE nobis 



Filaments either floating free or in layers, usually not attached to 

 the substratum at either end; trichomes of cells very little different 

 from one another, not provided with heterocysts or tapering into a 

 hair, simple or branched, with or without a sheath enclosing one or 

 more trichomes; propagation by hormogonia; spores unknown; goni- 

 dia ?. 



Ilomocysteae Bornet and Flahault, Tab. syn. d. Nost. fil. liet., 1885, 

 p. 197, Rev. I, 1886, p. 325 ; Gomont, Monogr. des Oscill., 1892, p. 289 

 (1893, p. 27, Repr.). 



It has seeemd best to continue the practice, introduced by the 

 French phycologists, of separating the Hormogonales into two sub- 

 orders, the Homocystineae and the Heterocystineae. The presence 

 or absence of heterocysts is so nearly an exact dividing character and 

 the exceptional cases so few and so readily dealt with, that it seems 

 unnecessary, as well as decidedly undesirable, to change the desig- 

 nations. Gomont (1899, pp. 30-33) has discussed the question, and 

 further details will be given in the discussion of the Heterocystineae. 

 The Homocystineae, as here defined, include all the Hormogonales 

 having neither heterocysts nor terminal hairs. It fonns a compact, 

 well defined, seemingly natural group. 



FAMILY 3. OSCILLATORIACEAE harvey 



Trichomes pluricellular, straight, arcuate, more or less uncinate 

 at the apices, or spirally twisted, simple, or rarelj^ with false branch- 

 ing, cylindrical, or slightly tapering at the apices, all of the cells 

 similar in shape and in function, with or without a sheath, single or 

 plural within a sheath; multiplication by means of motile (?) hormo- 

 gonia. 



Harvey, Ner. Bor.-Amer. Ill, 1858, p. 96 (in part) ; Kirchner, 

 Schizophyceae, in Engler and Prantl, Natiirl. Pflanzenfam. I, lo, 

 1898, p. 61. Oscillarideae Graj^ Nat. Arr. Br. PI., vol. 1, 1821, p. 80. 



It seems best to recognize a single family under the Homocystineae 

 and this was done in 1898 by Kirchner {loc. cit.) who is quoted above, 

 therefore, as final authoritj^, although the name in its present form 

 was used as early as 1858 by Harvey {loc. cit.), but in much more 

 extended sense. In the sense of Kirchner, Oscillatoriaceae include 

 both the Vaginarieae and the Lyngbyeae of Gomont (1893, p. 28. 



