204 
MILDEWS, RUSTS AND SMUTS 
UROGYSTIS, Rabenh. 
Forming coarsely powdery blackish sori at maturity, 
which burst through the epidermis ; spores in inseparable 
clusters, one or several thick-walled, dark coloured spores, 
surrounded by thin-walled, colourless, sterile cells ; ger¬ 
mination by a promycelium bearing slender promycelimn 
spores at the tip. 
Distinguished by the peculiar character of the spores, 
commonly called " spore-balls." The dark-coloured central 
cells are alone capable of germinating. 
Urocystis occulta* Rabenh. ; Plowr., Ured., p. 285. 
Sori forming long black streaks on stein, leaves and leaf- 
sheaths ; spore-balls globose or elliptical, formed of i—3 
dark, central, fertile spores, smooth, 10—18 p, surrounding 
sterile cells pale coloured. 
Syn. Uredo parallela, Berk. 
Uredo occulta, Rabenh. 
Polycystis parallela, Berk, and Broome. 
On Rye— Secale cereale) Barley— Hordeum vulgare, Arr- 
henatherum elatior, Lolium perenne, Triticum vulgare, 
Alopecurus agrestis, Poa pratensis. 
Germany, France, Belgium, and United States. 
Urocystis agropyri, Schroet. ; Plowr., Ured., p. 285. 
Sori forming long black lines on the leaves ; spore-balls 
subglobose, i—-3 dark-walled fertile cells, 8—12 p, sur¬ 
rounded by a few colourless sterile cells. 
Syn. Urocystis parallela. Berk, and Broome. 
Urocystis jischeri, Korn ; Plowr., Ured., p. 286. 
On Triticum repens, Arrhenatherum elatior, Festuca 
rubra, Bromus inermis. Car ex acuta, C. gla^^ca, C. muricata. 
German}’. 
Urocystis colchici, Rabenh. ; Plowr., Ured., p. 286. 
Imnning large black streaks and patches on the leaves, 
which soon rupture the epidermis and become powdery ; 
spore-balls globose or oblong, fertile dark-coloured central 
spores 2 - —4, 10—15 p, sterile peripheral cells rather thick- 
walled, two layers sometimes present, yellowish-brown. 
Syn. Uredo colchici. Link. 
Polycystis colchici, Strauss. 
On Colchicum autumnale, Muscari racemosa, Paris 
quadrifolia. 
Italy, Belgium, and Germany. 
Urocystis sorosporoides, Korn. ; Plowr., Ured., p. 287. 
Forming swollen pustules on the leaves, and elongated 
