Jan. 1904 ] 
Cultures of Uredineae in 1903. 
13 
me that the data are yet too meager to make it worth while to 
undertake to decide upon the nomenclature of the forms or 
species, which ever they may be called. 
In addition to the foregoing results seven species of rusts 
were grown, establishing aecidial and teleutosporic connections, 
not heretofore recorded. The species are partly autoecious and 
partly heteroecious rusts. 
I. Melampsora Medusae Thiim.—Teleutosporic material 
on Populus deltoides Marsh, was obtained in the vicinity of La¬ 
fayette, Ind., and although of inferior quality, for the poplar 
rust was not abundant in this region last year, it was sown on 
Larix decidua Mill. (L. Europaea DC.) April 28. After a 
rather long interval of 16 days I was surprised and gratified 
to observe the beginning of spermogonia (May 14) in good 
quantity; and five days later (May 19), the aecidia appeared, 
and proved to be a caeoma-form. A sowing on this host was 
tried last year 11 without infection, which is, however, easily ac¬ 
counted for by the fact that the host plants employed in 1902 
were very feeble. For the supply of Larix, used this year I am 
indebted to the generosity of R. Douglas’ Sons, proprietors of the 
Waukegan Nurseries at Waukegan, Ill. They sent without re¬ 
muneration 25 very thrifty young larch, suitable for 6-inch pots, 
which made vigorous growth when brought into the green¬ 
house. 
This species is the American representative of the European 
M. populina Lev., both species having their aecidia on Larix. 
That the American form is specifically distinct from the Euro¬ 
pean was pointed out by Klebahn 12 in 1899, the differences being 
especially marked in the form, size and markings of the uredo- 
spores, and in the apical thickening of the teleutospores. The 
American form may be characterized as follows: 
Melampsora Medusae Thuem. 
O. Spermogonia epiphyllous, numerous scattered, inconspicuous, pale 
yellow, papilliform, by vertical sections shown to be columnar or hem- 
nispherical, raised above the surface, 40-55/z, in diameter. 
I. Aecidia hypophyllous, numerous, scattered, small, less than .5 mm. 
in diameter, pale yellow; peridium absent; aecidiospores catenulate, 
globoid, 20 u in diameter; wall colorless, nearly 3 u thick, finely verru- 
•cose. 
II. Uredospores amphigenous, or sometimes only hypophyllous, 
roundish, small, less than .5 mm. in diameter, early naked, somewhat pul¬ 
verulent, orange yellow; uredospores oval, or obovate-oblong, 15-18 by 22- 
30 a 1 usually flattened on opposite sides; wall colorless, 2.5-3 fj.> thick, or up 
to 10 u on the flattened sides, sparsely and evenly, echinulate with fine 
papillae, except on the flattened sides which are smooth; paraphyses 
11 Bot. Gaz. 35- 11. 1903. 
12 Ztschr. f. Pfl.-Kr. p:144. 1899. 
