tii'i' University of California Publications in Botany L VoL - 8 



Ruprecht, Neue Pflanzen, 1852, p. 80, pi. 7. 



Dictyoncurum is one of several monotypic genera confined to the 

 west coast of North America. It was discovered by Wosnessenski in 

 the vicinity of Fort .Ross, California, and specimens were contributed 

 by him to Ruprecht. The reticulate character of the blade marks it 

 as distinct from all other genera. In its method of the dichotomous 

 splitting of the blade, beginning at the transition meristematic region 

 between the stipe and the blade, it closely resembles Lesson ia. 



Dictyoneurum californicum Rupr. 



Plate 70 



Holdfast and stipe as in the genus ; transition or growing region at 

 the juncture of the stipe and blade ; no mucilage ducts ; blade rigid 

 and somewhat brittle, margins smooth or with scattered short spine- 

 like projections, variable in width with age, up to 18 cm. wide, 4-6 dm. 

 long, increasing in number by dichotomous splitting in the transition 

 point, constantly eroding at the outer free end; the stipe portion of 

 the transition region constantly becoming prostrate after longitudinal 

 splitting, developing hapteres along the margin, and by wearing away 

 at the rear end the plants are multiplied vegetatively ; color yellowish 

 brown ; perennial. 



Growing on rocks in the lower littoral and upper sublittoral belts. 

 From Vancouver Island to Pecho, San Luis Obispo County, California. 



Ruprecht, Neue Pflanzen, 1852, p. 80, pi. 7; Setchell, Notes on 

 Kelps, 1896, pp. 46-48, pi. 1 ; Setchell and Gardner, Alg. N.W. Amer., 

 1903, p. 267 ; Farlow, Anderson and Eaton, Alg. Exsicc. Amer.-Bor., 

 no. 115; Collins, Holden and Setchell, Phyc. Bor.-Amer. (Exsicc), 

 no. XI; Tilden, Amer. Alg. (Exsicc), no. 519. Costaria reticulata 

 Saunders, Bot. Gaz., vol. 20, 1895, p. 58, pi. 7. 



Costaria reticulata Saunders (loc. cit.) w T as founded upon material 

 collected at Pacific Grove, California. His excellent illustration of 

 the species leaves no doubt that it is the Dictyoneurum of Kuprecht. 

 Saunders' illustration, unlike that of Ruprecht, is of a broad mature 

 blade, probably of the first or original blade and stipe of a young 

 plant, while the large illustrations of Ruprecht (loc. cit.) are of older 

 plants whose blades have recently split and which have no "midribs." 

 Superficially, in the wrinkled bullate character, the blade of Dic- 

 tyoneurum resembles that of a Costaria, but the tissue composing the 

 so-called "nerves" of the former is different and distinct from the 



