(>4(i University of California Publications in Botany [Vol.8 



57. Eisenia Aresch. 



Holdfast of dichotomously branched hapteres; stipe elongating 

 and persistent, bifurcate above, the two false branches being the 

 thickened lower margins of the original and subsequently eroded blade. 

 A small partial blade persists at the outer extremity of each false stipe 

 throughout the life of the plant, giving rise to numerous sporophylls 

 along the lower outer mafgin ; perennial. 



Areschoug, in Bot, Not., 1876, no. 3, p. 69, Observ. Phycol., part 5, 

 1884, p. 7. 



Eisenia is a distinct genus of two known species; one, E. arborea, 

 the type of the species, inhabiting the waters of southern California, 

 and the other, E. bicyclis (Kjellm.) Setchell, inhabiting the Japanese 

 waters. 



Eisenia arborea Aresch. 



Hapteres arising from very close to the base of the stipe, much 

 branched, the terminal branchlets fine and contorted ; stipe nearly 

 terete at the base, much flattened above, up to 1 m. long, tough and 

 rigid, containing mucilage ducts; blade in young plants entire, some- 

 what ovate, soon giving rise to short outgrowths, the pinnules, in the 

 transition region, later eroding from the apex to the transition or 

 meristematic region, which now becomes divided longitudinally estab- 

 lishing two meristems; these two now moving forward, giving rise to 

 the two twisted stipe-like portions, each bearing a short terminal 

 thickened blade, in turn bearing numerous pinnules or sporophylls 

 along the lower outer margins ; a third meristem remaining active at 

 the summit of the true stipe and elongating ; each blade bearing 30-50 

 sporophylls ; the sori in large irregularly shaped areas. 



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

 Southern California, south of Redondo. 



Areschoug, in Bot. Not., 1878, no. 3, p. 69, Observ. Phycol., part 5, 

 1884, p. 7; Setchell, Kelps of the U. S. and Alaska, 1912a, p. 164; 

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

 EckJonia radiata Areschoug, 1884, p. 13, in part (not Fucus radiatus 

 Turner). 



The plants reported by Saunders from Puget Sound, Washington, 

 and Wrangell, Alaska, proved to be large specimens of Laminaria 

 Andersonia with blades worn away. Areschoug reports it "in sinu 

 propre San Francisco" on the authority of Dr. G. Eisen, in honor of 



