354 MY GARDEN. 



(fig. 822), which grows on fruit trees in several places; and Lecanora 

 subfusca (fig. 823), which also grows on fruit trees. Some species 

 are found on the walls and dead wood of the bridges. There is a 

 species which 'grows on the trunk of a large willow-tree, which in one 

 stage of growth appears as a large white patch. It appears to grow 

 suddenly in mid-winter, when the pure white colour of the circular 

 patches is very striking and remarkable. On the hills above Heidel- 

 berg the trees are covered with lichens of large size ; but wherever 

 lichens attacked the boughs of the trees they died : whether or no 

 this was caused by the lichens, I had not sufficient facts upon which 

 to form an opinion. My attempts to cultivate the lichens have not 

 at present been attended with success, either out of doors or under 

 glass. Six hundred and fifty-eight species live in England. 



" Retiring Lichen climbs the topmost stone, 

 And drinks the aerial solitude alone." DARWIN. 



LIVERWORTS. 



I have already noticed the Marchantia 

 (fig. 824) amongst the garden weeds. The 

 M. polymorpha covers all the blocks of 

 sandstone out of doors as well as in the 

 glass fernery. It is, however, a very beau- 

 tiful plant, especially when in fruit, and 

 would be much more highly esteemed if 



FIG 824. -^Marchamia. * we had not a great deal too much of it 

 for the due preservation of our other plants. 



FUNGI. 



" And agarics and fungi, with mildew and mould, 

 Started like mist from the wet ground cold ; 

 Pale, fleshy, as if the decaying dead 

 With a spiric of growth had been animated ! "SHELLEY. 



A certain knowledge of Fungi is indispensable to the horticulturist, 

 and but few of us who cultivate plants have as much knowledge 



