1898.] 



on a Yorksldre Moor. 



631 



regions of the Old World, but also in the New, It abounds in 

 Greenland, where the Eskimo use the berries as food, and extract a 

 sjDirit from them. A very similar species, with red berries, occurs iu 

 the Andes. 



The heaths, bilberry, crowberry, and many other peat-loving 

 shrubs or trees, have a peculiar root structure. The usual root hairs 

 are wanting, and in their place we find a peculiar fungus-growth, 

 which invades the living tissues of the root, sometimes penetrating 

 the cells, There is often a dense mycelial mantle of interwoven 

 filaments, which covers all the finer roots. This looks like parasitism, 



Fig. 8. — Cross section of leaf of Crowberry. The lower figures 

 show one of the peculiar hairs and one of the stomates. Both 

 are confined to the inner, which is properly the under surface. 



but the fungus is apparently not a mere parasite, for the tree or shrub 

 shows no sign of injury, but thrives all the better when the fungus 

 is plentiful, and may refuse to grow at all if the fungus is removed. 

 Ehododendron, ling, most heaths, bilberry, crowberry, broom, 

 spurgeJaurel, beech and birch are among the plants which have a 

 mycelial mantle. If the native soil which clings to the roots of any 

 of these is completely removed, if the fine roots with the mycelial 

 mantle are torn off by careless transplanting, or if peaty matter is 

 withheld, the plant dies, or struggles on with great difficulty until 

 the mycelial mantle is renewed. Such plants cannot, as a rule, be 

 propagated by cuttings, unless special precautions are taken. Frank 



2 T 2 



