Nov., 1921] MAINS RUSTS ON NYSSA AND URTICASTRUM 445 
was correct in considering the fungus a rust and also disclosed that in 
addition to the uredinia abundant telia were present, most of which were 
white from the germination of the teliospores. A study of this rust showed 
that the telium consisted of a crust of one-celled, colorless teliospores, 
borne in chains of two or three. In these and other characters the rust 
seemed to belong in the genus Cerotelium. The characteristics and rela- 
tionships of the rust all pointed to a heteroecious life cycle. Since infection 
would have to occur in the fall, it appeared quite likely that the aecial 
stage either developed upon biennial parts of the host such as the needles 
of some conifer or was systemic. Since conifers were not to be found in the 
vicinity of the Urticastrum rust at Urbana, it appeared more likely that 
the aecial stage was systemic. Dr. Arthur immediately suggested Aecidium 
Dicentrae Trel. as the likely aecial stage, since not only is this rust systemic 
but unlike the usual Aecidium of the region it possesses large, subcuticular 
pycnia, a characteristic of many of the Melampsoraceous rusts. This 
conclusion was greatly strengthened by discovering in the herbarium a 
specimen of the Aecidiurri collected by Professor Anderson in the same 
woods earlier in the season. The only apparently serious objection to this 
connection was the manner of growth of Bicuculla Cucullaria (L.) Millsp. 
(Dicentra Cucullaria Tow.). This plant develops and flowers early in the 
spring and then soon dies down, so that by the time teliospores of the Urticas- 
trum rust are germinating, there is nothing of the Bicuculla plant above ground 
except an occasional corm. This connection would therefore necessitate 
an unusual type of infection. Aecidium Dicentrae, however, resembles so 
closely what it was felt the aecial stage should be that sowings were made 
by placing leaves bearing germinating teliospores of the Urticastrum rust 
on soil containing corms of Bicuculla Cucullaria. The pots of corms were 
placed out of doors during the winter and then brought into the greenhouse 
early the next spring. No infection appeared. In spite of this, it was 
still felt that the rusts of Urticastrum and of Bicuculla were connected. 
Another attempt was made this spring (1921) by sowing aeciospores of the 
Bicuculla rust sent from Urbana, Illinois, by Professor Anderson. This 
sowing produced typical uredinia upon Urticastrum divaricatum. The lack 
of results from the sowings of basidiospores upon the Bicuculla corms may 
have been due to the effect that the high temperature of the greenhouse had 
upon the development of the plants, since infected corms sent by Professor 
Anderson in the summer of 1920 when brought into the greenhouse this 
spring showed the rust in only a few cases and then only pycnia were pro- 
duced. 
Cerotelium Dicentrae (Trel.) Mains and Anderson comb. nov. 
Aecidium Dicentrae Trel. Trans. Wis. Acad. Sci. 6: 136. 1884. 
O. Pycnia amphigenous, somewhat scattered, usually near the margin 
of the leaf, conspicuous, subcuticular, violet becoming dark chestnut or 
chocolate-brown, applanate or discoidal, 160-200 /x in diameter by 40-60 ix 
high; ostiolar filaments wanting. 
