CHAPTER X. 



PELLIA AND FOTAEIA. 



PELLIA. 



458. General Characters. Of the three British 

 species, Pellia epiphylla the commonest and most widely 

 distributed is easily distinguished : it is monoecious (the 

 antheridia and archegonia are borne on the same plant), 

 while the other two species are dioecious. Other differ- 

 ences between the three species are given in 469. 



Pellia grows in spreading patches in moist places, 

 especially by the sides of streams. Examine the plants at 

 different times of year ; remove patches, together with 

 some of the soil, and cultivate them in dishes indoors, 

 keeping them moist and partially covering them with glass 

 sheets. 



In making a seasonal study of Pellia, note the following 

 points : late summer and autumn developing sporogonia ; 

 winter ripening and ripe sporogonia, resting thallus- 

 branches at apex ; spring elongation of seta, dehiscence of 

 capsule, dispersal of spores, branching of thallus, develop- 

 ment of sexual organs ; early summer mature sexual 

 organs, fertilisation, early development of sporogonium. 

 At each stage preserve specimens in alcohol or formalin, 

 for microscopical examination, in jars labelled with date of 

 collection. 



Isolate as much as possible of a single thallus from the 

 overlapping and matted branches that make up a patch of 

 Pellia, rinse in water to remove the soil from the lower 

 surface, and note 



(a) The smooth upper surface, wavy margin, and mode 

 of branching of the flat green thallus. 



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