22 University of California Publications in Botany [Vol. 10 



This form is intermediate, in several of its characters, between 

 F. furcatus f. typicus and F. furcatus f. luxurians. On drying it is 

 smoother than either of the above mentioned forms, the caecostomata 

 not standing out so prominently. 



The type (plate 9) was collected in May, and, although fruiting 

 abundantly, may possibly be immature, judging from the number of 

 blunt receptacles. No. 23526, Gardner, from San Juan Island, was 

 collected in July and the receptacles have apparently reached their 

 maximum size. The plants from this locality are scarcely typical in 

 every respect. The fronds average slightly narrower and the caeco- 

 stomata are much fewer, but it seems too close to be segregated under 

 a form name. Gardner, no. 1973 (Herb. Univ. Calif., no. 132743, and 

 in Collins, Holden, and Setchell, Phye. Bor.-Amer. (Exsicc), no. CX, 

 sub F. evanescens f. macroceplialus Kjellm.) is typical of f. elongatus 

 in color, character of branching, having mostly wide and usually 

 rounded angles, character of segments and receptacles, but varies from 

 the type in having very few caecostomata. It is certainly quite dif- 

 ferent from Kjellman's F. evanescens f. macroceplialus in all of its 

 important characters. Compare plate 9 with plate 46, representing 

 Kjellman's type. 



Fucus furcatus f. luxurians f. nov. 



Plate 10 



Frons distincte caulescens, cartilaginosa, alis attritis, costa densa 

 in eomplanatum stipitem transeunti, regulariter dichotoma, 4—5 dm. 

 usque ad 9 dm. alta, obscure olivaceo-viridis vel olivaceo-brunnea, costa 

 receptaculisque luteolis, disco radicali magno firmoque ; segmentis 

 variabilibus late cuneatis vel fere linearibus, saepe ad costam oblique 

 fissentibus, 1.5-3 cm. latis, terminale saepe latiori rotundatoque, caeco- 

 stomatibus numerosissimis, 300-350 in quoquo cm. quadrato, crypto- 

 stomatibus sparsis, paraphysum fasces longe exsertes gerentibus ; re- 

 ceptaculis manifeste definitis, 4—6 cm. longis, complanatis vel acum- 

 inatis ; conceptaculis numerosissimis. 



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

 belt. Northern and central California. 



Type, Gardner, no. 4327 (Herb. Univ. Calif., no. 201220), Moss 

 Beach, San Mateo County, California, July, 1918. 



Plate 10 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. 



