372 BOTANICAL GAZETTE [jxjne 



r 



as Myxosporiiim valsoideum (Sacc.) All. and Discula platani (Peck) 

 Sacc, Von Tavel (44) previously had connected D. platani with 

 G. nervisequunij and Beauverie (5) had shown that both of these 

 names are but synonyms of G. nerviseqmim. 



4. The pycnospores may be borne in cleistocarpous pycnidia on 

 old leaves on the ground. This stage had been found before and, as 

 was shown by Klebahn, had been named S par one ma platani Baumler 

 and Fusicoccum veronense C. Massalongo. 



I took up the study of this fungus in order to confirm Klebahn' s 

 work and to find whether the perithecia normally develop in this 

 country. In nearly all cases I w^as able to confirm Klebahn' s 

 results completely. In a few cases, however, there seemed to be some 

 discrepancies. These will be brought out in the following discussion 

 of the life-history. 



The disease due to this fungus, as it is commonly seen^ appears 

 on the veins of the sycamore leaf, killing a strip on each side of the 

 vein; later it often spreads to other parts of the leaf. The diseased 

 portions die and become brown, generally accompanied by a distortion 

 of the leaf. On the under side of the diseased spots, and occasionally 

 on the upper side the acervuli develop in abundance, being about 

 100-300 /x in diameter. The conidia develop in abundance on short 

 conidiophores. In moist weather, or when the leaves are placed in a 

 moist chamber, the spores ooze out in creamy white masses or in white 

 strings. They are usually about 10-14X4-6^^1., hyahne, slightly 

 granular, generally somewhat pointed at one end and more or less 

 rounded at the other. 



An examination of the leaves in late summer and autumn shows 

 that the petioles have been attacked also. Klebahn does not men- 

 tion this effect of the disease. Diseased patches may be formed by 

 the fungus growing down the petiole from the leaf blade, or they may 

 be entirely distinct from the leaf blade. Quite often, especially in the 

 autumn, these diseased spots are present at the very base of the petiole, 

 where it is attached to the twig. Whether the fungus passes from the 

 petiole into the twig was not determined, though many leaves were 

 examined; but this seems at least possible. Conidial pustules form 

 in these diseased petioles Just as on the leaves. The presence of the 

 disease on the petioles often causes a oremature fall of the leaves. 



