664 University of California Publications in Botany [Vol. 8 



65. Fucus (L.) Dec'ne and Thuret 



Fronds attached by a solid disk-shaped holdfast, complanate, with 

 more or less distinct percurrent midrib and alae of variable widths, 

 branching beginning 2-5 cm. from the base, dichotomous or subsecund, 

 stipe formed by thickening of the midrib and wearing away of the 

 alae; reproduction sexual, by antheridia and oogonia borne among 

 hyaline, more or less branched, sterile filaments, the paraphyses, within 

 cavities, the conceptacles, limited to the terminal, metamorphosed, more 

 or less swollen portions of the branches, the receptacles; oogonium 

 producing eight oospheres, or eggs, which escape together in a trans- 

 lucent utricle which soon disintegrates and frees the eggs ; antheridium 

 produces 64 antherozoids, each with a ' ' red eye spot ' ' and two laterally 

 affixed cilia of unequal length; fertilization effected after the eggs 

 escape from the membrane ; plants synoicous or dioicous. 



Decaisne and Thuret, Rech. sur Antherid., 1845, p. 13 ; Linnaeus, 

 Gen. Plant., 1737, p. 326 {Vim. mid.). 



For a discussion of the genus Fucus, see Gardner (1922). 



Key to the Species 



1. Fronds with abundant caecostomata 1. F. furcatus (p. 664) 



1. Fronds with few or no caecostomata 2 



2. Cryptostomata absent 5. F. nitens (p. 699) 



2. Cryptostomata present, usually abundant 3 



3. Fronds membranaceous 2. F. membranaceus (p. 673) 



3. Fronds coriaceous 4 



4. Cryptostomata few, fronds usually narrow 3. F. edentatus (p. 678) 



4. Cryptostomata more or less abundant, fronds wider 



4. F. evanescens (p. 681) 



1. Fucus furcatus Ag. 



Fronds usually rigid, often arborescent, more or less cartilaginous, 

 for the most part decidedly mucilaginous, regularly dichotomous, olive 

 green to yellowish ; segments usually relatively long, slightly cuneate 

 to linear, in some cases decidedly crisped, midrib prominent and per- 

 current and often yellowish, caecostomata usually abundant; recep- 

 tacles for the most part complanate, sometimes tumid, often decidedly 

 yellowish. 



Growing in the middle and lower littoral belts. From Sitka, 

 Alaska, to Oil Port, San Luis Obispo County, California. 



Agardh, Sp. Alg., 1820, p. 97; Icon. Ined., fasc. 2, 1821, pi. 14, 

 Syst., 1824, p. 279 ; J. Agardh, Sp. Alg., 1848, vol. 1, p. 209. Gardner, 

 Genus Fucus, 1922, p. 16, pi. 1, fig. 1 (copy of original of Agardh). 



