NEW SELAGINELLAS FROM THE WESTERN 



UNITED STATES 



By WILLIAM R. MAXON 



(With Six Plates) 



Within the past twenty years a considerable number of species 

 have been proposed in the group of Selaginella rupestris, nearly all 

 of which, judged by a critical comparison of their essential though 

 minute characters, are undoubtedly well founded. In all, about 

 twenty-five species have been described from the United States. 

 These are so various in gross form and habit, and under a dissecting 

 microscope or even by use of a good hand lens show such remark- 

 ably diverse and constant leaf and sporophyll characters, that it is 

 hard to conceive of their ever having been regarded as, for the most 

 part, " forms " of a single species. Extensive collecting, especially 

 in the Rocky Mountain region, is still necessary in order to clear up 

 the relationship of a few doubtful forms, and it is likely that explora- 

 tion in the Southwest will yield additional new species, since the 

 plants as a group are decidedly xerophilous or, at least, are able to 

 withstand long periods of drought, and so may be sought in those 

 arid out-of-the-way places that appeal chiefly to the natural history 

 collector. Specimens from any part of the southern and western 

 United States will, indeed, be gratefully received by the writer. 



Of the six species here described the first is one of the interesting 

 assemblage of species growing together, often intimately associated, 

 in the Organ Mountains of New Mexico ; the second is a plant of the 

 desert region of southern California, confused by Underwood with a 

 similar species from Zacatecas, Mexico ; the third, long known to the 

 writer as distinct, is a related plant from Arizona; the fourth and 

 fifth are species of southern California, brought to light by the 

 energetic field work of a small group of enthusiastic botanists ; and 

 the sixth is a strongly marked plant, not uncommon in the Glacier 

 National Park, recently discovered during the course of intensive 

 botanical collecting in that region. In the lack of a monograph or a 

 synoptical account of the group as represented in the United States, 

 it has seemed especially desirable to accompany the descriptions by 

 illustrations. These, besides assisting in identification, will serve to 



Smithsonian Miscellaneous Collections, Vol. 72, No. 5 



