30 Notes 0)t Parasitic Ascomycetes. — III. [Sess. 



A second species of Ephelina is named E. radicalis (Cooke) 

 Mass., and produces blackish gouty swellings at the base of 

 the stems of Yellow - rattle (Rhinanthus Crista - galli). It 

 attacks the living plant, but the mature ascophores do not 

 appear to be fully developed until winter, when the affected 

 stems have become dead. This species seems to be not 

 uncommon on roadsides, &c, but is only to be found after 

 careful search by pulling up the dead stems of the host- 

 plant. 



Among the parasitic fungi to be mentioned in connection 

 with this group are several species of Rhytisma, of which the 

 most familiar is Rh. acerinum (Pers.) Fr., common everywhere 

 on leaves of sycamore (Acer Pseuclo-platanus). In its early 

 stage, known as Melasmia acerina LeV., it forms on the living 

 leaves in summer conspicuous black spots resembling blotches 

 of pitch, and rather thicker than the substance of- the leaf. 

 Each spot is actually a stroma containing numerous small 

 cavities, in which are produced in autumn innumerable minute 

 spore - like bodies or spermatia. These are said to be in- 

 capable of promoting infection, and their precise function is 

 not yet clearly understood. After the fallen leaves have lain 

 on the ground during the winter until the following spring, 

 the stroma becomes swollen, and ridges are formed on the 

 upper surface, which ultimately split longitudinally and reveal 

 the pale disc. The spores are very long, needle-shaped, hyaline, 

 and arranged in a parallel fascicle in the ascus. 



Although very disfiguring to the trees on which it occurs, 

 and apt to cause injury by inducing untimely defoliation, the 

 Rhytisma can be easily got rid of by the exercise of a little 

 care. As the ripe spores are shed in spring, just at the 

 period when the young leaves are expanding, fresh infection 

 readily takes place at that time ; and this may be prevented 

 if the affected leaves are gathered and destroyed when they 

 fall in autumn, before the asci and spores have been 

 developed. 



Among the other species of Rhytisma may be noted Rh. 

 punctatum (Pers.) Fr., also occurring on living leaves of 

 sycamore, and closely allied to Rh. acerinum. It is readily 

 distinguished by the black spots being broken up into smaller 

 portions and crowded on a yellowish blotch. 



