628 University of California Publications in Botany [Vol.8 



southern limits of this species have not been satisfactorily determined. 

 W. C. Crandall (Pert, res. U. S., 1912, p. 210) has seen "beds as far 

 south as Cedros Island," off the coast of Mexico, and states that 

 "according to local fishermen these beds extend to Magdalena Bay." 

 The northern limit, as growing near Sitka, rests especially upon the 

 report of Edward C. Johnston (Fert. res. U. S., 1912, p. 215). 



Our Macrocystis of the north Pacific seems to grow in warmer water 

 than that of the Antarctic and south Pacific. While the southern 

 hemisphere form grows in the comparatively warmer waters of Peru 

 it also grows about Cape Horn in waters of extreme coolness. In our 

 Alaska waters, it seems to stop short at Sitka and does not go farther 

 west and north into the coldest waters of our region, Sitka being 

 decidedly under the isothere of 10° C. but just about on the isocryme 

 of 0° C. The coldest locality for Macrocystis seems to be South 

 Georgia, between the isocryme of somewhat below 0° C. and the 

 isothere of 5° C. 



2. Macrocystis integrifolia Bory 



Plate 62 



Fronds relatively slender, composed of a flattened, almost ligulate, 

 prostrate, creeping, rhizome-like portion, 2-3.5 cm. wide, profusely 

 and for the most part dichotomously branched, attached closely and 

 firmly to rocks by numerous, strong hapteres arising along its two 

 margins and giving rise to numerous free erect portions, relatively 

 slender, 5-8 m. long, bearing the vesicles with blades at their distal 

 ends; vesicles subspherical to broadly pyriform; blades denticulate 

 along the whole margin, 2.5-3.5 dm. long, 3.5-5 cm. wide, acuminate 

 at both ends. 



Growing on rocks at slightly below extreme low water mark. 

 Central California. 



Bory, in Diet, class, d'hist. nat., vol. 10, 1826, p. 9. 



At several localities along the coast of central California, notably 

 at Monterey Bay and Carmel Bay, for many years we have observed 

 quantities of a species of Macrocystis attached to boulders and rock 

 ledges at and just below low-tide level which, according to our judg- 

 ment, is entirely distinct from the abundant and widely distributed 

 M. pyrifera (Turner) Ag. We have thought that possibly it might 

 represent only stranded individuals of that species. The fundamental 

 difference between the two species as represented on our coast is the 



