666 University of California PuMications in Botany [Vol.8 



probably to be referred to f. typieus, but it is desirable to consult other 

 specimens of the distribution before deciding definitely. 



This form is abundant on the California coast, but less common 

 toward the north, being supplanted by numerous other forms. It 

 reaches its optimum growth in localities where the surf is only mod- 

 erately active. In such situations it attains its greatest height, not 

 infrequently specimens attaining a height of 4.5 dm., but when on 

 boulders exposed to a heavy surf, it remains much shorter, is more 

 arborescent, the alae wearing away up to the last segment. The 

 illustration on Gardner's plate 3 is of the former state, and that on 

 plate 2 is from an exposed situation at Fort Ross, California, pre- 

 sumably the type locality for the species. 



3. Fucus furcatus f . luxurians Gardner 



Plate 99 



Fronds cartilaginous, distinctly caulescent, the alae wearing away, 

 the much thickened midrib becoming the flattened stipe, regularly 

 dichotomous, 4-5 dm. (up to 9 dm.) high, dark olive green to olive 

 brown, midrib and receptacles yellowish, holdfast large and firm; 

 segments varying from broadly cuneate to nearly linear, frequently 

 splitting obliquely to the midrib, 1.5-3 cm. wide, terminal often wider 

 and rounded, caecostomata very numerous, 300-350 per sq. cm., 

 cryptostomata scattered, bearing fascicles of long exserted paraphyses. 

 Receptacles definitely delimited, 4-6 cm. long, complanate or decidedly 

 tumid, bi- tri-furcate, apices blunt or acuminate ; conceptacles very 

 numerous. 



Growing on boulders and rock ledges in the middle of the littoral 

 belt. Northern and central California. 



Gardner, Genus Fuctis, 1922, p. 22, pi. 10. 



Plate 99 represents a plant of this form in mature fruit, producing 

 receptacles for the first time. The receptacles in this specimen are 

 all complanate, a condition which prevails very commonly, but in 

 certain localities the receptacles are tumid and mucilaginous. 



Forma luxurians is closely related to forma typieus. The two forms 

 often grow intermingled, but may readily be distinguished by differ- 

 ences in size and color, forma luxurians being the more robust, and of 

 a lighter brownish or yellowish color in the upper parts, particularly 

 the receptacles. The southern limit of the form, as of all forms of 



