June 1902] Cultures of Uredineae in 1900 and 1901 
51 
mens were obtained early in June 1902, and are issued simulta¬ 
neously in Ohio F., No. 75. 
The technical description of the proposed species is as fol¬ 
lows : 
Rhytisma concavum Ell. & Kellerm. n. sp. — Stromata epiphyllous 
but also visible below, forming thin, black, thickly scattered blotches, 1-4 
mm. diameter, orbicular or subangular, the surface uneven, surrounded 
by a pale yellowish, narrow margin, more or less concave below and the 
margin broader and paler, at maturity rupturing by radiating fissures, in 
the oblong forms a central elongated fissure also occuring and in the 
larger ones a circular area being cut out, the hygroscopic lobes strongly 
recurved when moist exposing a light yellowish, later sordid yellow then 
blackish disk. Asci 80-110x8-10 ,u, oblanceolate, much elongated below, 
strongly acute at the apex, accompanied by abundant slender and 
at the tips. Spores 20-35 x 2-3 [i hyaline, nearly straight to strongly 
elongated mostly flexuous paraphyses about 4 ^ wide, usually enlarged 
curved, slightly thicker at one end in which are large clear granules. 
On leaves of Ilex verticillata; spores mature in June. Type speci¬ 
men in Herb. W. A. Kellerman. 
CULTURES OF UREDINEAE IN 1900 AND 1901 
BY J. C. ARTHUR. 
The first especially important cultures of plant rusts made by 
the writer were conducted in 1899, and the results published in 
the Botanical Gazette for April 1900 (29:268-276). During the 
two following years only a small number of cultures were made, 
and for a number of reasons the results have not been put into 
type until now. This article is, therefore, the second of the series. 
The method pursued in most cases in making the cultures 
has been stated in the preceding article. It was, in brief, to re¬ 
move spores with a knife from the host, and place them on a 
dampened plant which it is desired to infect. The plants are 
grown in pots. After the spores are sown the whole plant is 
covered with a bell jar and kept shaded for a day, or sometimes 
two days. The plants are then uncovered and placed on a 
greenhouse bench, where they remain until the period of ob¬ 
servation is ended. 
In 1900 the only cultures made that require mention were 
with Euphorbia rust. The results supplement and confirm those 
made in 1899 (Bot. Gaz. 29:270-271). It was again found that 
spores from Euphorbia nutans would grow upon the same species, 
but not upon E. maculata. It seems quite probable that this rust, 
Uromyces euphorbiae C. & P. possesses specialized forms. The 
record is as follows: 
