FIELD BOOK OF PONDS AND STREAMS 



of these cells are not only thin but are perforated with large 

 pores, and water can pass to and fro through them with the 





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Fig. 57. — I, Leafy branches of Sphagnum, an 

 acute-leaved peat moss, bearing spore capsules; 

 2, without spores; 3, spore capsule, enlarged. 



greatest ease. These colorless cells account not only for 

 the paleness of sphagnum mosses, but for their extraordinary 

 power of absorbing water. Moist sphagnum has long been 

 used by florists to wrap plants for shipping and during the 

 Great War dry sterilized sphagnum was much used as an 

 absorbent wound dressing. 



Seed Plants — Angiosperms 



The parts of the flower. — Aquatic seed plants have essen- 

 tially the same structure as their terrestrial relatives and many 

 of them thrive just as well on a damp shore as they do in the 



66 



