1925] Setchell-Gardner : Melanophyceae 627 



be confined to grooves in the leaves (cf. Hoffman, 1911, p. 155) as 

 Smith and Whitting (1895, p. 84, pi. 20) found them, as did also 

 Skottsberg {Joe. cit.). 



The sporelings of Macrocystis have been observed by R. P. Brandt 

 (1923, pp. 4-7, fig. 2), who did not succeed, however, in clearly elu- 

 cidating the complete life-history of the gametophyte. Brandt also 

 deals with the polymorphy, especially as regards the shape of the 

 bladders, due to more quiet or rougher waters. 



Key to the Species 



1. Fronds arising from masses of branched hapteres 1. M. pyrifera (p. 627) 



1. Fronds arising from stout creeping rhizomes 2. M. integrifolia (p. 628) 



1. Macrocystis pyrifera (L.) Ag. 



Plates 64 and 65 



Holdfast very large, often becoming nearly a meter in diameter in 

 the typical deep sea form ; stipe at first dichotomously branched, estab- 

 lishing 2-8 growing points ; the main stipes become 30-50 m. long, bear- 

 ing at their summits the young differentiating blades and along the 

 greater part of their length, at regular intervals, the mature lateral 

 blades, each with a pyriform bladder at its base, which is in turn sup- 

 ported by a short cylindrical stipe ; blades rigid, coarsely rugose, 3-5 

 dm. long, 5-9 cm. wide, with spinulose margins. 



Growing on rocks usually in 20-30 m. of water. It extends from 

 Sitka, Alaska, to Magdalena Bay in Lower California, but is a plant 

 of the outer coa.sts, exposed to wave action. 



Agardh, Sp. I, 1820, p. 47 ; Setchell, Kelps of the U. S. and Alaska, 

 1912a, p. 158; Postels and Ruprecht, Illus. Alg., 1840, p. 9, pi. 6; 

 Saunders, Alg. Harriman Exp., 1901, p. 431, pi. 60 ; Setchell and 

 Gardner, Alg. N.W. Amer., 1903, p. 270 ; Collins, Holden and Setchell, 

 Phyc. Bor.-Amer. (Exsicc), no. XXXTX; Tilden, Amer. Alg. 

 (Exsicc), no. 518. Fucus pyriferus Linnaeus, Mantissa, II, p. 311; 

 Turner, Hist. Fuc, vol. 2, 1809, p. 103, pi. 110. 



We have not attempted to segregate varieties or forms of this 

 species, since we have not been able to determine any exact lines of 

 cleavage. The varying shape of the bladders from globular to 

 extremely elongated, the varying breadth, length, dentation, wrinkling, 

 etc., of the leaves seem possibly matters of age and character of habitat. 

 There are also some indications of the possibility that this species is 

 only the deep water condition of the next. The exact northern and 



