SPHAGNUM. II 



The position of the pores on the ventral surface of the branch leaves instead 

 of on the dorsal surface as usual, is, I think, to be explained by the dorsal position 

 of the chlorophyllose cells. The object of the pores being to facilitate the passage 

 of water through the plant, it is natural that they should be most numerous at the 

 chief point of junction of adjacent hyaline cells ; this is usually on the dorsal surface 

 of the leaf, but in this species it is on the ventral surface, owing to the dorsal position 

 of the chlorophyllose cells. This is borne out by the fact that the only two other 

 British species in which the pores preponderate on the ventral face are likewise the 

 only two in which there is the same (dorsal) position of the chlorophyllose cells, with 

 the exception of S. Lindbergii ; here, however, the pores are very few in number, 

 and although certainly more numerous on the back of the leaf are to be found in the 

 front also. 



6. Sphagnum subsecundum Nees. (Tab. VII. A.) 



Plants tall and rather slender, 4-12 inches high. Stems dark 

 brown in the type, pale green in some of the varieties. Cuticular 

 cells in a single layer. Stem leaves large or small, oval-deltoid 

 or oblong-lingulate, at the summit rpunded with the margin 

 incurved, and finely toothed or fringed at the apex. Cells all 

 rather narrow, the marginal ones extremely so, forming a border 

 narrow above, much wider towards the base ; upper cells fibrose 

 and porose, occasionally the lower ones also. Branches 2-4, the 

 divergent ones spreading or deflexed, often flagelliform. Retort 

 cells slightly recurved at apex. Branch leaves more or less sub- 

 secund, very variable, from broadly ovate to oblong-lanceolate, 

 acuminate or obtusely pointed, 3-5 toothed at tip, very con- 

 cave. Hyaline cells narrow, densely fibrose, with many small 

 pores, usually arranged in a regular row along each side of the 

 cell. Chlorophyllose cells in section very narrowly elliptical, 

 reaching both the front and back of leaf. 



Var. /3. contortum Schp. (S. conlortum Schultz). Stem 

 usually green, sometimes dark brown. Branches stouter and 

 more crowded than in the type, more or less curved and con- 

 torted ; the leaves larger and broader, usually more closely 

 imbricated and less secund, so as to give the branches a smooth, 

 terete appearance. 



Var. y. turgidum CM. Branches swollen, terete, usually 

 contorted, acute ; branch leaves very broad, truncate at apex. 



Var. 8. obesum Schp. (S. contortum var. obesum Wils.) 

 Plants usually submerged, robust, dark coloured. Branches thick, 

 obtuse, the leaves more or less secund, broadly ovate or ovate 

 lanceolate ; stem leaves resembling the branch leaves in form and 

 areolation. The pores in the hyaline cells are few and scattered, 

 not arranged in regular rows along the cell walls. 



