332 LYCOPODIALES 
derivative. Of the former S. sinulosa, A. Br., is the best known, and it 
will be seen that its vascular anatomy, which differs from that of all 
other Selagined/as, shows points of interesting comparison on the one 
hand with Lycopodium, and on the other with the dendroid Club-Mosses. 
The hypocotyl, and the lower parts of the axis, with its branches, are 
traversed by a cylindrical stele, which is peculiar in having a central 
A 
Fic. 173. 
Selaginella spinulosa. A. Transverse section of the trailing stem showing central 
protoxylem. @=pericycle; 5=protophloem; c=phloem parenchyma; ¢=metaxylem. 
X275. S8=transverse section of upper part of axis, showing seven protoxylems. X 350. 
C-G=scheme of arrangement of the protoxylems in sections taken successively from 
below upwards. (After Harvey-Gibson.) 
strand of protoxylem surrounded by metaxylem: this is further invested 
by a narrow band of phloem surrounded peripherally by a sheath 
resembling a pericycle, and by the trabecular endodermis so characteristic 
of Selaginella (Fig. 173): according to Strasburger both of the latter 
layers are derived from the cortex, as they are also in Lycopodium. 
In passing upwards in the strobilus the stele loses its peculiarity of 
having a central protoxylem: for the strand divides, and the branches 
diverge outwards to the periphery of the wood, where they appear in 
1 Lettungsbahnen, p. 458. 
