32 



FARLOW ON THE GYMNOSPORANGIA 



On unripe fruit and stems of Crataegus crus-galli, C. punctata, C. oxyacantha and other 

 species of Crataegus, on Amelanchier canadensis and on cultivated quinces and apples. 



Not rare from Massachusetts (Farlow), Vermont (Frost), New York (Peck), to North 

 Carolina (Curtis), South Carolina (Ravenel), and Missouri (Engelmann). 



By far the most beautiful species of the genus which we have, at once attracting the 

 popular eye by its brilliant orange or almost cinnabar colored spores and shining white 

 peridium. It is generally found on the young fruit, though it is occasionally found on the 

 stems and petioles, but I do not recollect having seen aecidia on the leaves. What I take 

 to be spermogonia of this species are found on the leaves apart from the aecidia. R. 

 aurantiaca is often accompanied by R. lacerata, but one cannot consider the former to be 

 a form of the latter, which grows on the fruit rather than leaves, for the differences in the 

 spores and cells of the peridium are too marked to warrant any such supposition. The 

 peridia of the present species are more rigid than those of our other species, and the cells 

 cohere throughout, except at the tip where the peridium splits into comparatively few 

 short teeth, and does not become lacerate or penicillate as in most of the species. The 

 spores are large for the genus Roestelia, and instead of the brownish tinge common in 

 other species, they are bright orange. The cell-wall is quite thick and striate. In drying, 

 the spores become pale, but their size and cell-wall even then are sufficient to distinguish 

 present from other species. 



R. aurantiaca is represented in Herb. Curtis by several specimens, including some col- 

 lected by himself in North Carolina. He apparently considered them all forms of R. lac- 

 erata, at least, they are so labelled. The species is particularly apt to attack the different 

 species of Crataegus, and the peridia attain a large size on the small berries of that genus. 

 It is reported by Peck to occur on Amelanchier, but I have never myself seen it on that 

 host. Perhaps the most striking form is that which is often found on quinces in Eastern 

 Massachusetts. I have collected specimens in Newton and I have received others from 

 Pepperell, Miss Freeman ; and from near Salem, Mr. Robinson ; and there are specimens 

 in Herb. Curtis and the Sprague collection from Mr. John Russell. One sometimes sees 

 a quince two inches in diameter more than half covered by the bright orange aecidia 

 and occasionally small apples are affected in a similar way. R. aurantiaca is generally 

 found in midsummer, I have, however, seen it on C. crus-galli as late as October. 



After the preceding detailed account of the species of Gymnosporangium and Roestelia 

 of the United States, one naturally wishes to know how far the view first promulgated by 

 Oersted is confirmed by cultures made with American species. Oersted recognized three 

 species of Gymnosporangium, and, at first, four species of Roestelia growing in Denmark. 

 He was afterwards induced to believe that two of the supposed Roesteliae, R. lacerata and 

 R. penicillata, were only forms of a single species, and he considered that he had proved 

 that G. fuscum was connected with R. cancellata ; G. clavariaeforme with R. lacerata, 

 including in that the form R. penicillata ; and G. conicum with R. cornitta. Thus, 

 there were no superfluous species of either genus in Denmark, that is, there was no 

 species of one genus which could not be matched with a species of the other genus. 



