March 1904] Minor Mycological Notes. Ill 
63 
I have been impressed with the marked characteristics of P. 
tridactyla — especially the location and direction of the appen¬ 
dages, and their striking dichotomal tips — and do not hesitate to 
label this form as a true species, not a variety of P. oxyacanthae 
as is done in Salmon’s Monograph. 
Referring to Earle’s “Notes on the North American forms of 
Podosphaera,” in the Botanical Gazette, 9:25-6, Feb. 1884, it is 
to be observed that this mycologist evidently did not have any 
true P. tridactyla; the decision that all his forms represented only 
one species was undoubtedly correct and he properly retained the 
name Podosphaera oxyacanthae (DC.) DeBary. The portion of 
his statement of interest here is as follows: “The differences 
that do appear are chiefly in the size of the perithecia and in the 
number and length of the appendages. As these vary more 
widely in perithecia from the same leaf than do the averages of 
the different forms, there seems no ground for their separation 
into distinct species, unless we allow more weight to the difference 
of host plant than is usual in the Erysiphei; but they should 
be considered as belonging to a large, widespread, variable species, 
comparable with Erysiphe lamprocarpa, Lev. and Microsphaera 
penicillata, Lev.” 
It has seemed desirable, even if my “note” is somewhat 
lengthened, to furnish the evidence for the opinion above ex¬ 
pressed as to the autonomy of the form under consideration; ac¬ 
cordingly outline figures have been reproduced on Plate 73. The 
Figs. 1-6, sufficiently explained below, represent P. oxyacanthae. 
In marked contrast to these are Figs. 7-9, which represent P. 
tridactyla — Fig. 7 drawn from a European specimen, and Figs. 
8 and 9 from the Seattle (Washington) specimen. The dichoto¬ 
mal tip has its branches placed at right angles and usually they 
are much elongated — never so directed in P. oxyacanthae. The 
apical insertion of the appendages which are erect — at least more 
or less so — is also characteristic (Fig. 9). There is no approach 
to the more or less equatorial or basal insertion, and horizontally 
spreading appendages as in the case of P. oxyacanthae (Fig. 6). 
Those interested in the synonomy would consult Salmon’s 
complete list in the Monograph. But it may here be remarked 
that Wallroth in 1838 named the plant Alphitomorpha tridactyla; 
in 1851 it was listed as Podosphaera kunzei by Leveille — which 
includes the species under consideration as well as the typical P. 
oxyacanthae; in 1870 we find the following satisfactory designa¬ 
tion: Podosphaera tridactyla (Wallr.) DeBary. 
Explanation of Figs. 1-9, Plate 73. 
Fig. 1 shows tip of appendage of Podosphaera oxyacanthae, specimen from 
West Virginia (Millspaugh). Fig. 2, ditto, from Missouri (Tracy & Galloway). 
Figs. 3 and 4, ditto, from Kansas (Kellerman & Swingle). Fig. 5, ditto, from Maine 
(Ricker). Fig. 6, Perithecium from P. oxyacanthae, S. Dakota (Griffiths). Fig. 7, 
tip of appendage of P. tridactyla from Germany (Krieger). Fig. 8, ditto, from 
Seattle, Washington (Parker). Fig. 9, Perithecium also from latter specimen. 
