\Chap. XLIX FERNS, CLUB MOSSES AND EQUISETUMS 669 



(Fig. 314), also grow in temperate climates, and as far north as New- 

 foundland and Labrador. They are much more abundant in the northern 

 conifer forests than in the deciduous forest of the Central States. The 

 tropical forms are frequently epiphytic. Many of the species have long 



Fig. 314. A club moss {SelagincUa apm) widely distributed on dry rocks. 

 The half-decayed branch in the background is 3 inches in diameter. Photo by 

 E. S. Thomas. 



creeping stems; in others the stems are erect. The stems usually branch 

 dichotomously. Most of the species are perennials, but a few of the 

 smaller ones are annuals. 



Some species of Selaginella grow in dry climates. During the rainy 

 seasons the numerous stems are spread out in the form of a dense 

 rosette. During dry weather the stems curye upward and inroll toward 

 the center of the plant, with the result that the whole plant has the 

 form of a ball and may be blown about (Fig. 315). When moisture is 

 again available, the stems unroll and new roots grow. Such plants are the 

 so-called "resurrection plants." The plant rolls and unrolls even when 

 dead. 



