Parv 6, 1921] AECIDIACEAE 425 
first pustular, soon naked, light cinnamon-brown, pulverulent, ruptured epidermis notice- 
able; urediniospores broadly obovoid, 19-23 by 24-30 4“; wall pale-tawny or nearly colorless, 
moderately thin, 1.5 4, minutely and rather closely echinulate, the pores not very distinct, 
3 or 4, equatorial. 
Ill. Telia hypophyllous, scattered, small, 0.1-0.3 mm. across, early naked, pulvinate, 
chestnut-brown, ruptured epidermis inconspicuous ; teliospores ellipsoid, 27-32 by 35-45 u, 
rounded at both ends, slightly or not constricted at septum; wall smooth, chestnut-brown, 
concolorous, moderately thick, 2.5-4, thicker at apex, 4-9 uw; pedicel often inserted 
obliquely, colorless or somewhat tinted, terete, 6-10, thick, thin-walled, fragile, about 
length of spore. 
On CARDUACEAE: 
Baccharis sordescens DC., Morelos. 
TYPE Locality: Cuernavaca, "Morelos, on Baccharis sordescens. 
DIsTRIBUTION: Known only from the type locality. 
243. Dicaeoma exornatum (Arth.) Arthur & Jackson. 
Puccinia exornate Arth. Bull. Torrey Club 38: 370. 1911. 
Eriosporangium exornatum Arth. N. Am. Flora 7:214, 1912. 
O. Pycnia amphigenous, loosely grouped, punctiform, large, honey-yellow, not especially 
conspicuous, globoid-flask-shaped, 120-160 » in diameter. 
I. Aecia h'ypophyllous, rather closely seated in orbicular groups surrounding the pycnia, 
groups 1-3 mm. across on larger discolored, unthickened spots, at first bullate, roundish, 
0.3-0.5 mm. across, soon dehiscent, orange-colored fading to dirty-white, ruptured epidermis 
overarching, conspicuous; peridium wanting; aeciospores globoid, 24-27 by 26-32; wall 
colorless, thick, 3-5 », coarsely verrucose with closely set oval beads arranged in longitudinal 
or slightly spiral series. 
II. Uredinia hypophyllous, scattered or somewhat grouped, round, 0.1-0.2 mm. across, 
soon naked, low, pulverulent, pale cinnamon-brown, ruptured epidermis inconspicuous; 
urediniosperes globoid or obovoid-ellipsoid, 20-24 by 24-30 wu; wall thin, I-1.5 4, very pale- 
yellow, finely and sparsely echinulate, the pores indistinct, apparently 3 and approximately 
equatorial. 
III. Telia hypophyllous, resembling uredinia but darker in color, 0.1-0.3 mm. across, 
soon naked, low, applanate, cinnamon-brown becoming cinereous by germination, ruptured 
epidermis inconspicuous; teliospores oblong, 19-24 by 37-48 u, rounded at both ends, some- 
what constricted at septum; wall golden-yellow, smooth, thin, 1 y, slightly thicker above, 
2-4 u; pedicel colorless, delicate, terete, 5—9 « in diameter, once to twice length of spore. 
On CaRDUACEAE: 
Baccharis rhexioides H.B.K., Costa Rica; Guatemala. 
Baccharis thesioides H.B.K., Guatemala. 
TYPE LOCALITY: Guatemala City, Guatemala, on Baccharis thesioides. 
DistriBurion: Central America. 
244. Dicaeoma oaxacanum (Dietel & Holway) 
Arthur & Jackson. 
Aecidium fragile Holway, Bot. Gaz. 31: 331, hyponym. 1901. 
Puccinia oaxacana Dietel & Holway; Holway, Bot. Gaz. 31: 331. 1901. 
Eriosporangium oaxacanum Arth. Résult. Sci. Congr. Bot. Vienne 343. 1906. 
O. Pycnia amphigenous, few in a group, minute, inconspicuous, globoid, 80-100 u broad. 
I. Aecia amphigenous, abundant, in groups of 2-6 crowded about the pyenia, often soli- 
tary; peridium cylindric, 0.1-0.2 mm. in diameter, ‘0.1-0.3 mm. high, colorless, very delicate 
and evanescent; peridial cells loosely overlapping, 40-65 u long, angularly oblong-fusiform in 
face view, linear in radial section, 6-10 « across, the outer wall thin, about 1 4, smooth, the 
inner wall somewhat thicker, about 2 uw, strongly verrucose; aeciospores ovoid-oblong or ob- 
long-fusiform, often acute at one or both ends, 16-25 by 29-40 u; wall colorless, uniformly 
thin, about 1 », strongly verrucose with closely set beads. 
II. Uredinia hypophyllous, not abundant, scattered, round, very small, 0.1-0.3 mm. 
across, early naked, pulverulent, light cinnamon-brown, ruptured epidermis barely noticeable; 
