502 BOTANICAL GAZETTE [JUNE 
Ecology of heather.—One of the most commendable features of modern 
ecology is seen in the present tendency to focus attention on some particular 
plant which is examined as to its responses and limitations. A notable example 
of this type of investigation is seen in Miss RAYNER’s studies of Calluna_ 
vulgaris. In a preliminary paper” she pointed out that while the plant has 
been regarded as a typical calciphobe, it occurs in sharply defined communities 
on the chalk downs in Wiltshire and cia and appears able to compete 
with the vegetation characteristic of the downs. According to this investiga- 
An examination of the germination and seedling habits of Calluna® shine 
that the seedlings developed normally upon the soil from the heather areas 
and abnormally upon the chalk soil. Upon the latter the germination was 
reduced and retarded, the development of the root and shoot arrested, and 
the leaves were small in size and red in color. The seedlings were found to be 
infected with a mycorhizal fungus shortly after germination, the mycelium 
coming from the seed coat which seems to have been infected while still in 
the ovary. Seed can be sterilized with no effect upon germination, but in 
the absence of infection complete arrest of root formation occurs, showing 
the relation of Ca/luna to the root fungus to be obligate 
rther examination of this symbiosis,“ already noted in this journal,’s 
parts of the plant infecting the testa, but not the embryo and endosperm of 
the seed. The fungus was isolated, grown in pure cultures, and sterile seedlings 
were inoculated with resulting normal development. 
In the most recent contribution Miss RAYNER has succeeded in demon- 
strating by experimental cultures that Calluna vulgaris will not grow on 
calcareous soils because of an inimical factor, chemical in nature, present in 
such soils. The exact chemical character of this factor is as yet unknown, 
but it seems probable that it is effective by altering the infectibility of the root 
cells of the seedlings and their relations with the mycelium after infection. 
It does not seem to affect the fungus when growing outside the plant.—GEo. 
D. Futter. 
Rayner, M. C., and Jones, W. N., Preliminary observations on the ecology of 
Calluna vulgaris on the Wiltshire and Berkshire Downs. New Phytol. 10:227-240- 
Jigs. 2. 1911 
%——.. The ecology of Calluna vulgaris. New Phytol. 12:59-76. pl. 7: 
——, Obligate symbiosis in Calluna vulgaris. Ann. Botany 29:97-153- 
pl. é fe 4- 1915. 
T. Gaz. 60:166. 1915. : 
16 ppb , M. C., The ecology of Calluna vulgaris. U1. The calcifuge habit. 
Jour. Ecol. 9: 60-74. pl. f. 102%. 
