526 BOTANICAL GAZETTE {JUNE 
scorched in preparation, either fruited or produced abortive fruit bodies, 
while no fruiting was observed in other cultures. The scorched condi- 
tion of the medium would of course give rise to substances not generally 
present in the culture medium, and it is suggested that this condition of 
nutrition may have been the determining factor. It is also of interest 
to note that the fruit bodies from which the spores were obtained were 
frozen solid when collected, 
which did not appear to injure 
the viability of the spores. 
Cultures of another very 
interesting agaric were obtained 
from the pathologist of the 
Forest Products Laboratory at 
Madison, Wisconsin, namely 
Armillaria mellea Vahl. This 
species forms a whitish my- 
celium which soon turns to a 
dark brown. The interesting 
feature, however, is the forma- 
tion of the so-called ‘rhizo- 
morphs.” These are described 
as appearing in nature as 
shining black strands often re- 
sembling the roots of the host. 
They appear soon after inocula- 
tion on agar cultures, ramifying 
throughout the substratum. 
Here, however, they are of a 
shining light gray color, and 
are flat and ribbon-like, often 
branching dichotomously (fig. 3). Upon pentrating to a free surface 
these rhizomorphs immediately give rise to the ordinary vegetative 
mycelium.—V. H. Younc, University of Wisconsin, Madison. 
Fic. 3 
THE AMOUNT OF BARE GROUND IN SOME MOUNTAIN 
GRASSLANDS 
In July torr the writer staked out a series of 19 quadrats for study 
of the grassland of a mountain park at Tolland, Colorado. In that year 
collections were begun and censuses of some of the quadrats made. 
The plan was adopted of estimating at intervals the percentage composi- 
