318 



PLANT STUDIES 



contain both kinds, for Mosses are both dioecious and monoe- 

 cious. The two principal groups are as follows : 



207. Sphagnum forms. — These are large and pallid bog 

 mosses, found abundantly in marshy ground, especially of 

 temperate and arctic regions, and are conspicuous peat- 



■d 



B C D t £ J" A 



Fig. 291. Sphagnum ; A, a leafy branch (gametophore) bearing four mature gporo- 

 gonia ; _£, archegonium in whose venter a young embryo sporophyte (em) is de- 

 veloping ; C, section of a young sporogonium (sporophyte), showing the bulbous 

 foot ispf) imbedded in the apex of the pseudopodium (pis), the capsule (k), the 

 columella (CO) capped by the dome-shaped archesporium (spo), a portion of the 

 calyptra ica), and the old archegonium neck (ah) ; D, branch bearing mature 

 eporogonium and showing pseudopodium (ps), capsule (k), and operculum (d) ; 

 E, antheridium discharging sperms ; F, a single sperm, showing coiled body and 

 two cilia.— After Sctiimper. 



iormers (Fig. 291). The leaves and gametophore axis are 

 of peculiar structure to enable them to suck up and hold a 

 large amount of water. This abundant water-storage tissue 

 and the comparatively poor display of chlorophyll-contain- 

 ing cells gives the peculiar pallid appearance. 



208. True Mosses. — This immense and most highly organ- 

 ized Bryophyte group contains the great majority of the 



