NORTH AMERICAN CERCOSPOR^. 



37 



The above notes, which agree wel] with the original description 

 and figures of Fresenius. are from specimens collected in Michigan, on 

 cultivated celery, by Professor Beal, and communicated to us by Dr. 

 Farlow. Specimens on celery collected in Italy by Prof. Passerini (comm. 

 de Thuemen) appear to be the same as the Michigan specimens, except 

 that the spots are less definite. Specimens in de Theumen's M. U., No. 

 483 (on FetroseUnum), and in Rabh. Myc. Eur. 2071, on the same host, 

 differ from the above in their much smaller, paler spots, larger and less 

 numerous tufts of hyphse which are darker and more distorted above, 

 bearing obloug 1—3 septate, conidia, 30—50 x 5—7 /J-, without any slender 

 prolongation above. Specimens on Pastinaca collected in ^ew York by 

 Prof. Halsted (comm. Dr. Farlow^ have hyphiB and conidia scarcely dis- 

 tinguishable from the last mentioned species in their microscopical char- 

 acters, but there are no spots, the minute, blackish tufts of hyphae being 

 evenly and thickly distributed over the lower surface of the leaves or 

 occupying small, irregular areas bounded by the veinlets. In the speci- 

 mens on Pastinaca in de Thuemen's M. U. 1169, we find no Cercospora. 

 In specimens on Pastinaca from Iowa, the hyphse are confined to small 

 and scattered areas bounded by the veinlets of the leaf, but on these areas 

 the tufts of hyphEe are densely crow^ded so as to appear elf used, and are 

 of a light cinereous hue, perhaps on account of the abundant conidia 

 w^hich are, the same as in the other specimens on Pastinaca, 1—3 septate. 

 Specimens on Pastinaca sent from Wisconsin by Professor Trelease are 

 the same as the Iowa specimens on Pastinaca, only the conidia are longer 

 and more distinctly attenuated above, though only 3-septate. On the 

 Wisconsin specimens was also a Bamularia with oblong-cylindrical, 10— 

 20x3/-'-, 1-septate conidia, growing on small (2—3 mm.), definite, rusty 

 brown spots and having the general appearance of the true C. ^p^i,Fres. 



We have left for the present all the forms above noted under C. Apii. 

 Fres. though strongly of the opinion that the variety on Pastinaca at 

 least will yet prove specifically distinct. 



c. Spots angular or irregular. 



51. Cercospora BcEmiERi^, Pk. 34th Rep. N. Y. State Mus., p. 48. 

 Spots small, numerous, often confluent, angular, limited by the 



veinlets, brownish, sometimes becoming arid and grayish. Hyphae hypo- 

 phyllous, tufted, short, subflexuous, colored. Conidia subcylindrical or 

 bacillary, generally curved, 4— 5-septate, colored, 40—80 long. The 

 spots, though numerous are not very conspicuous, on account of their 

 very dull color; the tufts of hyphse hIso are very numerous, but so 

 minute as scarcely to be visible to the naked eye. They are compactly 

 united at base in a sort of sclerotoid mass as in C. venturioides. 

 On leaves of Boehmeria cylindrica, N. Y. (Peck.) 



52. Cercospora Liriodendri, Ell. & Hark, Bull. Torr. Bot. Club. 

 VIII, p. 27. N.A. F. 645. 



Hypophyllous. On small (2 mm.) angular, brownish spots, mostly 

 bounded by the veinlets of the leaf. Hyphse fasciculate, erect, sparingly 



