oat Se - Ae G e”ire Ne we et Le nd 
AES SEE SENS oa Se ep RS SPEER EH EPA eye aURNT eh Ee 
pinata ices 
CLADOCHYTRIUM ALISMATIS. 
CONTRIBUTIONS FROM THE CRYPTOGAMIC LABORA- 
TORY OF HARVARD UNIVERSITY. XLIX. 
G. P. CLINTON. . 
(WITH PLATES II-IV) 
Wuite collecting at Glacialis pond, Cambridge, Mass., in 
October 1900, the writer found Cladochytrium Alismatis Bisg. on 
Alisma Plantago L. Although the season was so far advanced 
for this plant that all of the leaves were dead and in many cases 
broken off, still enough infected ones were obtained to show that 
the fungus was not uncommon in that locality last year. The 
discovery of the fungus is especially interesting since this is the 
first time it has been found in America, and also because the 
study of it revealed the possession of a peculiar — 
Sporangial stage that it was not known to possess. 
This Cladochytrium occurs on the leaf blades, petioles, ast 
peduncles, forming lead-colored, generally subcircular sori I-2™™ * 
in diameter. These are generally distinct from one another, and © - 
on the woody tissues are apt to have more of an elongated shape. | 
In the leaf blades the so-called spores, Or resting sporangic, : ‘ 
occupy the cells between the two layers of epidermis, producing _ 
a slight pustule which in the green leaves, as shown by exsiccati 
Specimens, is surrounded by a rather inconspicuous discolored — 2 
area, While the sori are long covered by the epidermis, in ‘the a 
dead leaves this eventually breaks open and the sporangia 
become scattered, thus leaving small circular holes in the a 
Chytia and pits in the woody tissues. 
Although a temporary mycelium is aéveloped i in this genus, - 
‘the fungus i in this case was so far matured when discovered t a 
NO sign of it could be made out. From one to three or four spo- 
‘Tangia were found in the eS cells ie the leaf blade ~ 
g he peduncle there 
(fg. 33), wines int the more el 
