Howe: American Species of Alectoria 



129 



characters to distinguish the varieties. Jubata in the Tuckerman 

 sense, like barbata, therefore, it will be seen includes collective 

 specific characters. 



Crombie has brought into use the chemical tests to separate 

 implexa from jubata, but though I have faithfully tried them I 

 fail to find the reactions conclusive or helpful. Crombie's results, 

 moreover, do not agree with those given by Nylander. Stizen- 

 berger, however, claimed that Nylander's tests " brachte allmalig* 

 Licht in das Chaos," and though not questioning their diagnostic 

 aid, I have sought and found structural differences of value, 

 though intergradation undoubtedly occurs. 



The brown, pendulous species of Alectoria are plants of wide 

 cosmopolitan distribution. From their high development, like 

 Usnea, during an evidently extended evolution by three modes of 

 reproduction (spore, soralial, fragmentary) they have become 

 wonderfully variable, and as with all the filamentous, cylindrical 

 species now rarely develop apothecia. The fragmentary method 

 of reproduction is not only the most common, but hinders the 

 apothecial, which consequently becomes rare. There seems to 

 exist for each lichen species, however, an area where particularly 

 acceptable environment finds a usually sterile species fruiting 

 commonly, i. e., Usnea angulata Ach. in the Bolivian Andes. In 

 both hemispheres a maximum length of 30 to 40 cm. is reached, 

 and the plants show a color gradation from almost black-brown 

 to pale gray. A parallelism with Usnea in the matter of distri- 

 butional development is clearly shown ; central Europe and the 

 northern Pacific coast supporting the most luxuriant growths, — 

 eastern United States the most reduced. 



I have included in this paper a diagnosis and description of 

 true jubata that students may recognize the limits of jubata, and 

 be able to make comparisons with our allied species. A clear 

 understanding of jubata will I think eliminate the future erro- 

 neous recording of it from this continent. Personally I have yet 

 to see a typical specimen from North America, its nearest con- 

 generic representative being Fremontii, while the variety implexa 

 that follows, is the plant common to the larger part of our area. 



* Stizenberger uses this word to indicate early discrepancies among authors. 



