1925] Setchell-Gwdner: Melcmophyceae 711 



Growing in the upper sublittoral belt. Avalon, Santa Catalina 

 Island, California. 



Setchell and Gardner, in Gardner, New Pac. Coast Mar. Alg. I, 

 1917, pp. 388-390, pis. 34, 35. 



73. Sargassum Ag. 



Plants attached b}^ a more or less irregular, warty, solid, paren- 

 chymatous base, or by numerous stolon-like growths from the main 

 axis, at most but a few decimeters high ; frond variously branched, con- 

 sisting of a main basal part, or stipe-like portion terete or slightly 

 angled remaining short with transition region near the end, bearing 

 few to many branches on all sides, alternately arranged ; these main 

 branches more or less elongated, filiform, terete or slightly angled, 

 more or less branched, developing short, flattened, generally more or 

 less horizontal, sterile branches (leaves) with midrib and cryptosto- 

 mata; the receptacles and vesicles, variously arranged and modified, 

 developing in the axils of these leaves ; plants monoecious or dioecious ; 

 oogonia large, containing a single egg. 



Agardh, Sp. I, 1820, p. 1. 



In treating of the species of Sargassum found within our territory, 

 we are accepting the genus as established by C. A. Agardh in Species 

 Algarum in 1820, following the arrangement and restriction of the 

 species as proposed by J. G. Agardh in his Species Sargassorum, 1889, 

 and further modified and amplified by A. Grunow in Additamenta, 

 1915, 1916. There is still much need of further investigation of the 

 species growing in the Gulf of California and around the islands in 

 the Pacific Ocean off the coast of Mexico. 



Key to the Species 



1. Leaves on all orders of branches decompound 1. S. Palmeri (p. 712) 



1. Leaves simple 2 



2. Vesicles, leaves, and receptacles intermixed, forming a heteroclyte cyme.. 3 

 2. Vesicles, leaves, and receptacles not intermixed, not forming a hetero- 

 clyte cyme 6 



3. Receptacles two edged, apex and margin serrate-dentate. 5. S. Bryantii (p. 714) 



3. Receptacles terete 4 



4. Leaves slightly flattened to filiform 3. S. guardiense (p. 713) 



4. Leaves flattened, asymmetrical, dentate 5 



5. Vesicles and receptacles not spinose 2. S. acinacifolium (p. 713) 



5. Vesicles and receptacles more or less spinose 4. S. lapazeanum (p. 714) 



6. Receptacles ancipitally angulate, margins serrate-dentate, conceptacles 



on lateral surfaces 7 



6. Receptacles cylindrical, more or less papillate, conceptacles on all sides. 11 



