146 THE SELAGINELLA RUPESTRIS GROUP. 



imbricated rows, one row on each angle of the spike. 

 They are often triangular in outline, broad at base, and 

 end in a short awn. The margins bear abundant cilia 

 that are so small as not to be easily seen. The megaspo- 

 rangia are especially abundant and bright yellow in 

 colour, quite distinguishable without a lens. 



The sand-barren selaginella has thus far been reported 

 from Florida, Louisiana, and Texas, but it is likely to 

 be found in suitable situations in any of the sand-bar- 

 rens along the Gulf coast. Its slender, cylindrical, grey- 

 green, erect stems will be easily identified when found. 

 It was originally described ?& Selaginella arenaria. 



Selaginella Bigelovii. 



In the days when it was customary to refer everything 

 at all resembling Selaginella riipcstris to that species, it 

 was described as having stems from six inches to a foot 

 long. The plant that is nowadays called Selagiuclla 

 rnpcstris is much smaller, and at its best does not reach 

 the minimum length quoted. An explanation of the 

 discrepancy is found, however, when we take into con- 

 sideration one of its forms recently named Selaginella 

 Bigelovii. In this the stems ordinarily reach a length of 

 six or eight inches, and in vigorous specimens are, of 

 course, still longer. 



It is likely to surprise the beginner to learn that 

 Selaginella Bigclovii was ever referred to Selaginella 

 rupcstris. Aside from its long stems, its habitat and 

 manner of growth are sufficiently different to separate it. 

 It is an erect or ascending species, with stems that pro- 

 duce roots only near the base. For some distance 

 above the soil, the stems are commonly unbranched, or, 



