1922] Gardner: The Genus Fucus on the Pacific Coast 5 



For many rears I have observed, in their native habitats, extensive 

 beds of Fucus growing on our western shores extending from central 

 California to Sitka. Alaska, and have been much confused and deeply 

 perplexed in trying to determine the best disposition to make of the 

 multitude of forms here represented. The range for the genus extends 

 from Oil Port. San Luis Obispo Comity. California, its southern limit 

 as at present known, into the Arctic Ocean, and is practically unbroken. 

 In the southern portion of the range the problem is comparatively 

 simple, there being but few forms represented. The complexity 

 increases northward, and the optimum for luxuriance in growth of 

 numbers of forms and of individuals seems to be in the general latitude 

 of Sitka. Alaska. 



I have come to the conclusion that we have in this genus an example 

 of extreme plasticity, in which the forces at work breaking up 

 continuity are vigorously active. Plants with new combinations of 

 characters are arising and. to still further complicate the matter, these 

 probably hybridize with one another. 



For ultra popular usage, a very few species, perhaps four, would 

 thoroughly suffice to include all of the forms of the genus, e.g., F. 

 serratus, F. vesiculosus, F. spiralis, and F. evanescens. Morphologically 

 serratus is obviously distinct, vesiculosus is always dioicous, while all 

 others are synoicous. Forms which have been included even under 

 spiralis and evanescens might be confused because of ovei'lapping 

 characters. Such a disposition would doubtless, for scientific usage, 

 meet with hearty disapproval. On account of the nature of the genus, 

 any disposition at present can only be approximate in the face of our 

 vastly incomplete knowledge concerning a variety of points. 



Without further delay. I am arranging our multitude of forms 

 under five rather comprehensive species, viz., F. furcatus Ag., F. 

 nit, , is nob.. F. edentatus De la Pyl., F. membranaceus nob., and F. 

 evanescens Ag. These I have so diagnosed as to make them include 

 all the forms which I have grouped around them, and have designated 

 the group as species major. Under each species major, respectively, I 

 have grouped 13. 0. 5. 6, and 21 forms which I feel quite convinced 

 are entities, giving rise to others of their kind in successive generations 

 in the same manner as does any other species ; however, my investiga- 

 tions may not have been extensive enough as yet to prove this state- 

 ment. These forms I am designating as species minor and, following 

 customary usage. I am calling them formae of the respective species, 

 awaiting further investigation and experimentation to prove the 



