272 University of California Publications in Botany [Vol.8 



12. Ulva dactylifera S. and G. 



Plate 21, fig. 1 



Frond sessile or with a very short stipe; basal portion orbicular 

 or reniform, much crisped, 2-4 cm. high, giving rise from the upper 

 margin to 1-6 lanceolate, simple or occasionally branched lobes or 

 laciniae with plane midrib and much crisped margins, 5-15 cm. high, 

 0.5-1.5 cm. wide ; membrane of basal portion 50/i, thick at the margin, 

 up to lOOjLt thick in the middle, with cells 16-20/x diam. in the surface 

 view, quadrate to 2 times as long as wide in section, membrane of the 

 laciniae 40-50/x thick on margin, up to IQOjn thick in the middle, with 

 cells 12-16ju diam. in surface view, quadrate to 5 times as long as 

 wide in section ; chromatophore filling the outer half of the cell. 



On exposed rocks, uppermost littoral belt. Southern California 

 to Mexico (San Roque?). 



Setchell and Gardner, Phyc. Cont. I, 1920, p. 285, pi. 26, fig. 1. 



We have along the Californian coast two species related to Ulva 

 fasciata, neither of which seems to be exactly like the Mediterranean 

 species. Both are characterized by long, narrow fronds or laciniae, 

 much thicker along the middle and with thinner, very much crisped 

 margins. One of these, Ulva dactijlifera, possesses a comparatively 

 broad, though short, undivided basal portion from which arise the 

 several narrow, elongated, crisped laciniae. Neither the basal portion 

 nor the laciniae show distinctly toothed margins. The other species, 

 Ulva taeniata, is either simple, long, slender, plane and dentate below, 

 but with crisped margins above, or divided to the very disk itself 

 into two or three such divisions. The "midrib" portions differ 

 slightly in thickness in the two species and the cells of the ' ' midribs 

 differ in proportions. 



Ulva dactylifera has been distributed under no. 221 b (sub "Ulva 

 fasciata'') of the Phycotheca Boreali- Americana. Unfortunately the 

 plants under this number are not uniform. We have examined no. 

 221 b in two copies. In one, the plant is certainly, although not 

 typically, U. dactylifera. In the other it seems rather to be a form of 

 Ulva Lactuca. 



Ulva dactylifera is nearest to U. fasciata f. costata Howe (1914, 

 p. 20, pis. 1, 2, f. 10-23), but differs as to the basal portion, thickness, 

 and possibly also in proportions of cells. It differs from U. fasciata 



