— 13— 

 HYPNUM OCCIDENTALE S. & L. 



In Bull. Torr. Club, 17:277. 1890, N. C. Kindberg described Thuidium 

 Vancouvericnse as a new species from Vancouver Island. In Cat. Can. 

 Plants, 6:183. 1892, the same plant is described as Hetcroclatiiion Vancoit- 

 vcrienst\ and in Eur. & N. Amer. Bryine;:^ it is referred to the author's new 

 genus, Psciidolcskclla. It turns out, however, that this supposed new 

 species, which has done good service in three genera in no less than six 

 years, is identical with Hypnmii accident ale S. & L., described and figured 

 in Icon. Muse. Supp. ioi.pl. Si. 1874, as an authentic specimen from Dr. 

 Kindberg, which I owe to the kindness of Prof. J. M. Holzinger, and a por- 

 tion of Sullivant's type, which I owe to the courtesy of Mrs. Britton, clearly 

 prove. 77ntidiitiii r<?//tt'//7'<v/V;/i-d- must therefore be relegated to the long 

 list of synonyms for which we have to thank our worthy trans-atlantic con- 

 freres, and which might easily have been avoided, had all of them been as 

 anxious to ascertain what American bryologists have done, as some of them 

 have been eager to make new species of American mosses. — (/'. A'. lies/. 



i 



LICHENS— THE USNEAS. 



In commencing our study of lichens, it has been thought best to begin 

 with Usnca and some of the varieties, as they are so generally called 

 mosses. 



The so-called Florida moss which grows so luxuriantly on the trees in 

 the Southern States, is often supposed to be a lichen. It is, in fact, a flower- 

 ing plant, and belongs to the Bromeliaceae, or Pineapple family. Its 

 botanical name is Tillandsia usncotdes, the specific name indicating its 

 resemblance to Usnca. 



Some botanists think lichens are only a higher order of fungi, others 

 who have studied them closely accord them a place by themselves, between 

 the fungi and mosses.* 



A lichen is composed of an alga and a fungus, the alga supplying 

 chlorophyll or green matter, the fungus absorbing moisture from the atmos- 

 phere and mineral substances from the substratum. The two live together 

 in what is called a symbotic relationship, the one necessary to the life and 

 development of the other. 



As this article is intended for beginners in the study of these interesting 

 plants, a few definitions of the principal parts of Usnca may be helpful. 



The///^?///o- is the vegetative portion, taking the place of the stem and 

 branches in the flowering plants. In r.f;/(V? it is fruticose or shrub-like. In 

 some species it is erect and rather rigid, in others it is pendulous and soft, 

 and through the centre runs a white cottony substance which is called the 

 medullary cord. 



Fibrils are the fine hair-like branches found on the main thallus. In 

 some species these are stiff, in others they are soft. Fibrils are also found 

 on the margin of the apothecia. 



* Instructions for collecting and mounting lichens can be found in Asa Gray Bulletin, 

 Vol. VI, No. I, Febrary, iSyS. 



