Vol. 31, pp. 171-172 December 30, 1918 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



A NEW SELAGINELLA FROM OKLAHOMA AND 



TEXAS.* 



BY WILLIAM R. MAXON. 



Among a few pteridophytes from Oklahoma recently re- 

 ceived for identification are specimens of a new Selaginella, 

 described below. An examination of herbarium material 

 discloses other specimens from Texas and Oklahoma under 

 cover of S. Wrightii, with which species there is no close rela- 

 tionship. 



Selaginella Sheldoni Maxon, n. sp. 



Plants prostrate, the main stems up to 10 or 12 cm. long, everywhere 

 rooting, densely pinnately branched, the lower branches often spreading, 

 up to 4 cm. long, mostly bipinnate, the ultimate branchlets in general 

 short, simple or with very short knoblike divisions, sterile, or the apical 

 ones often fertile to their base; stems, branches, and minor divisions all 

 densely leafy, the leaves mostly curving upward, giving a definite dorso- 

 ventral aspect to the plant. Leaves crowded, imbricate, those of the 

 under side appressed, soon discolored, the others secund or at first spread- 

 ing, all herbaceous, grayish green, plane above, convex beneath and very 

 narrowly sulcate to the apex, subulate to lance-subulate, setigerous at 

 the acutish apex (the seta slender, white, persistent, 0.6 to 0.8 mm. long, 

 serrulate), ciliate throughout, the cilia 7 to 10 on each side, the lower and 

 middle ones the longest (0.14 to 0.2 mm. long), whitish, widely oblique, 

 straight or falcate, the upper ones shorter, ascending, passing into elongate 

 hyaline serratures at the apex; leaves of the under ranks (seta included) 

 2.4 to 2.7 mm. long, 0.4 to 0.5 mm. broad, the others slightly shorter. 

 Spikes few, arcuately ascending, 8 to 12 mm. long, 1 to 1.3 mm. in dia- 

 meter; sporophylls ovate to narrowly deltoid-ovate, long-acuminate, 

 short-auriculate, very narrowly sulcate along the dorsal keel, short seti- 

 gerous at the tip (the seta 0.3 to 0.5 mm. long, pungent, serrulate), short- 

 ciliate, the cilia 16 to 22 on each side, whitish, the basal ones 0.07 to 0.09 

 mm. long, spreading, those above shorter, oblique, passing into pungent ser- 



• Published with the permission of the Secretary of the Smithsonian Institution. 

 42— Proc. Biol. Soc. Wash., Vol. 31. 191S. (171) 



