Horse-hair Blights. 
BY 
T. FETCH, B.A., B.Sc. 
A MONG the many tropical mycelia which are abnormal, 
either in habit or structure, none is more striking than 
those which have received the general appellation of Horse- 
hair Blight,” a designation which has been bestowed by 
planters in Ceylon, India, and the West Indies on thin 
rhizomorphic mycelium, which spreads freely over bushes and 
trees at some height above the ground. As far as these 
mycelia have been identified, they belong in all cases to some 
species of Marasmius, the common species in the Eastern 
tropics being Marasmius equicrinis, and that in the West 
Indies (according to the records) Marasmius sarmentosus. 
The following details relate chiefly to those species which 
have been found in Ceylon. 
Marasmius equicrinis MueU, 
The mycelium of this species is the common horse-hair 
blight of Ceylon. It consists of a smooth, tough, black cord, 
from one-tenth to one-eighth of a milhmetre in diameter, 
which runs in all directions over bushes and trees, up to a 
height of 20 feet above the ground, attached to the living 
stems and leaves at intervals of one to four centimetres, or 
throwing out long free threads to adjacent branches. Its 
course is quite a random one. After proceeding along a 
branch for a short distance, it may leave it and attach itself 
to a leaf, and after crossing several leaves may return to its 
original branch. Or it may travel from a branch to a leaf 
viâ the leaf stalk, and may make a complete circuit of one 
surface of the leaf before proceeding further. In general, 
the whole of the mycelium is aerial ; it is not connected with 
any mycelium on the ground, and does not ascend the tree 
from the ground level. It has been observed at the base of 
Annals of the Royal Botanic Gardens, Peradeniya, Vol. VI., Part I., Aug., 1915, 
