30 University of California Publications in Botany [Vol. 10 



Fucus edentatus f. costatus f. nov. 

 Plates 23 and 24 



Frons tenuis, subcoriacea, 15-25 cm. alta, regulariter dichotoma, 

 luteola; segmentis manifeste linearibus, comparative longis, supra 

 axillas in latere diminuatis, usque ad 5-8 mm. latis, terminalibus 

 2-4 mm. latis, costa valde exposita, percursa, alis angustis et mem- 

 branaceis, cryptostomatibus sparsis, prominentibus ; receptaculis mani- 

 feste definitis, integris vel vulgo bifidis, 20-35 cm. longis, apicibus 

 acutis; conceptaculis paullo numerosis conspicuisque. 



Growing on rocks in the lower third of the littoral belt. Lower 

 Puget Sound region, "Washington. 



Type, Gardner, no. 2333 (Herb. Univ. Calif., no. 201199), East 

 Sound, Orcas Island, Washington. July, 1910. 



Fucus evanescens f. angustus, Gardner, no. 694, and in Collins, 

 Holden, and Setchell, Phyc. Bor.-Amer. (Exsicc), no. 926 (cf. Setchell 

 and Gardner, Alg. N.W. Amer., 1903, p. 284) . This form does not seem 

 to be very generally distributed in the Puget Sound region, having been 

 observed in only a few localities. 



The plants distributed in the Phycotheca Boreali-Americana as 

 no. 926 were from the type locality, but were taken from the upper 

 limit of the belt of distribution when the tide was well in. They are 

 considerably battered and worn away, and thus cannot be said to be 

 in typical condition. Plate 23 represents a young plant, the type, 

 mostly in typical vegetative condition. Plate 24 represents two plants, 

 showing the extremes in variation in the width of the fronds. Speci- 

 mens as narrow as the narrower sterile one on the plate are rare, 

 and at some future time may have to be considered as distinct. The 

 illustrations were all made from dried material. 



This form resembles closely F. evanescens f. angustus Kjellm. in 

 width of fronds, and was so referred as is cited above. Subsequent to 

 the above publications, material of that species, collected and deter- 

 mined by Kjellman on the Vega expedition, has been received at the 

 Herbarium of the University of California (no. 132699). The lack of 

 a prominent percurrent midrib, almost complete absence of crypto- 

 stomata, and especially the very small receptacles of Kjellman 's 

 material, point out unmistakably that our plant is of a different lineage. 



