—66— 



Genus Ramalina^ Ach. Lich. Univ. 122 et 598. 1810. 



Description: Thallus caespitose or pendulous, branched; cortex glabrous, 

 striate, papillate, rugose, (puberulent?) or ciliate (in one species); structure 

 complex (decomposed); laciniae terete, subterete, compressed, or reticulate; 

 virescent to stramineous (rarely dichroic); medulla arachnoid, axis loosely arach- 

 noid (or partially chondroid in a few species). Gonidia stratified (heteromerous), 

 Protococcoid. Soredia or soralia normal. Cephalodia occasional, pale. 



Apothecia terminal, subterminal, marginal or lateral; scutelliform, ap- 

 planate or concave, rarely convex or lacerate; marginate, disk pale. Asci clav- 

 ate, containing eight spores; paraphyses gelatinous, slender, apices crassate. 

 Spores bilocular, rarely tri- or quadri-guttulate, hyaline, straight or curved, 

 ellipsoid or fusiform (rarely bistort). Spermogones subimmersed or papillate, 

 dark or pale. Sterigmata simple, rarely articulate. Spermatia cylindrical, 

 apices obtuse. 



Observations: In my papers on the other genera of this family I drew for 

 myself the arbitrary line of the 15th parallel north latitude, and this has forced 

 upon me the consideration of many extratropical species, our field and distribu- 

 tional knowledge of which is seriously lacking. I shall therefore do little more 

 than list the species that have been attributed to Mexico and the Greater An- 

 tilles. The material representing the same comprises rarely more than the types. 

 It is interesting to note that almost more species (12) have been described from^ 

 Mexico and Cuba than from all the rest of North America. In this connection, 

 for example, the genus Usnea is represented in North America proper^ by only 

 eight distinct species, and in Europe by only nine, whereas from the continents 

 of South America, Africa, Asia, and Oceania one hundred and ten species at 

 least have been described. The reason is not far to seek. The problems of 

 distribution have met with little correlated study, the types are scattered, the 

 described species insufficiently known, — consequently many of the specimens 

 of each small collection that find their way to the botanist, in the absence of 

 comparable material and distributional knowledge are described as new. It is 

 for this reason that in the family Usneaceae I am confining my work to North 

 America. 



The sections already proposed by Drs. Stizenberg, Steiner, and Wainio do 

 not seem to me particularly satisfactory. One, Corticatae Stnr., B. includes such 

 diverse species as ceruchis and Duriaei their homology being only in a none 

 too well marked cortical structure— which in the entire genus is of the one, de- 

 cofnposed type. In fact the members of the genus show but little variation in 

 the essential thalline characters, which undoubtedly explains, as has been said,, 

 not only how easily the genus has been recognized, but also the great difficulty 

 in distinguishing species. There are but two really distinctive characters, — 

 one made use of by Tuckerman, the chondroid axial filaments (almost of generic 

 importance) of ceruchis and homalea, — the other that of spore form. As I have 

 used spore characters, outside of septation, for sectional distinction, they seem 

 to offer again here the most natural division. All measurements and descrip- 



^ Ramalina = twigs, shoots — Latin ramale. 



2 See Proc. Thoreau Mus. Nat. Hist. 1: 15-25. 1913. 



