340 BROOKLYN BOTANIC GARDEN MEMOIRS 
and Pole Evans® in his careful investigation of the histology of nine 
species of cereal rusts has shown that while the young haustoria of 
various species may be small and sac-like, or even “ hammer-headed”’ 
in others, the prevailing type of mature haustoria in these cereal rusts 
seems to be the cylindrical or branched form. 
Attention was called in the earlier description of Botryorhiza to 
the fact that Lutman had figured botryose haustoria in Doassantia 
and it was there suggested that this Porto Rican rust might have some 
other features in common with smuts. But the fact that the sporifer- 
ous hyphae are sent out through a stoma or through the ruptured 
epidermis before the spores themselves are cut off from their tips, and, 
further, that there is produced in Botryorhiza (and apparently in rusts 
in general) a definite, superficial hymential layer from which the spores 
arise constitutes two essential points of difference from the smuts. 
The latter, as Lutman has clearly emphasized,° have their spores pro- 
duced either from a group of deeply imbedded multinucleate hyphae, 
which break up directly into spores (in the Ustilaginaceae) or from 
the tips of the side or main branches of the prevailingly binucleate 
hyphae (as in the Tilletiaceae). 
It has also been brought out in the description of the characteristics 
of Botryorhiza that the mycelium is composed of a branching system 
of very coarse hyphal threads. These hyphae measure from 5 to 7 
in diameter. In my own work on various rusts, I had never before 
met with such a coarse mycelium. Pole Evans,’ however, has called 
attention to the fact that the mycelial threads of Puccinia glumarum 
reach the relatively enormous size of 10 to 19 u in diameter; also 
Dodge in his paper in this Memoir® has noted that Farlow® and 
Wornle!® have found the hyphae in Gymnosporangium Ellisit to be 
exceptionally large, being, according to the latter author, about 8 pu 
in diameter. 
5 The cereal rusts. I. The development of their uredo mycelia. Annals of 
Botany 21: 441-446. 1907. 
OES Cho (Os WAI 
Og Coy Ds AUS 
8 See p. 128. 
°The gymnosporangia of the United States. Ann. Mem. Boston Soc. Nat. 
Hist. 1880: 1-38. 
10 Anatomische Untersuchung der durch Gymnosporangium-Arten hervor- 
gerufenen Missbildungen. Forst. Nat. Zeits. 3: 68-84; 129-172. 1894. 
