Mosses and Lichens 



Normally they are in the crown (capihiluni) of the plant, but 

 by an elongation of an erect branch near the apex of the stem 

 they are often left behind so as to appear to have 

 grown from the side. 



The pedicels are thick and stocky. [The Sphag- 

 num pedicel (pseudopodium) does not have the same 

 origin as the pedicel of other mosses]. 



The lids (opercula) are flattened in the form of 

 an inverted saucer. These are normally cast off 

 by the contraction of the spore-case wall. Some- 

 times a lid remains attached at one point and opens 

 to permit spores to escape or closes to protect 

 them. Sometimes, if wet, a lid does not fall, then 

 the spores germinate within the spore-case and 

 the growing embryos burst the spore-case and 

 escape. 



The spores are of two kinds large four-angled 

 spores (tetrahedral macrospores) and small many- 

 angled spores (polyhedral microspores). The small 

 spores are supposed to be the spores of a parasitic 

 fungus which lives upon the developing spores of 

 the moss. Two hundred and fifty-eight species in 

 all are known, seventy-four being found in North 

 America. 



Sphagnum 

 tguarrosum. A 

 plant with a 

 sporophyte 

 rising from the 

 perichaetial 

 leaves at its 

 summit ; the 

 slender pedicel 

 bears a globu- 

 lar spore-case 

 closed with a 

 saucer-like lid 

 and having a 

 ragged veil at 

 its base. 



THE PALE TINT OF PEAT-MOSSES 



The pale tint of peat-mosses is due to the struc- 

 ture of the leaves. When the moss is wet, the large cells are 

 rendered more transparent and the colour of the small cells can 

 be seen through them. When the moss is dry and the green 

 cells are less evident, then it is paler green or even white. 



THE METHOD BY WHICH PEAT-MOSSES ABSORB WATER 



The tiny openings of the large cells communicate with similar 

 openings in adjoining cells. When the atmosphere is dry, as 

 has already been said, the large cells are filled with air; but as 

 soon as the atmosphere is moist, the surrounding water rushes 

 through the holes on one side of the large cells and the air is 



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