306 GYMNOSPORANGIUM 
feidia on Crataegus Oxyacantha, C. monogyna, Pyrus 
communis, July—August; teleutospores on Juniperus ecom- 
munis, April and May. Rather common. (Figs. 280, 231.) 
The teleutospore-mycelium is perennial in the branches of the Juniper ; 
the spores are produced in spring and germinate immediately. The 
zcidia can be produced on the Hawthorn in two to four weeks or more 
after infection. Their spores in turn infect young shoots of Juniper, 
in which the mycelium gives rise to teleutuspores in one year (von Tubeuf), 
or two years (Plowright), and in each succeeding year so long as the branch 
survives. The mycelium in Crataegus is purely local and annual. 
The experimental culture of this species has been performed 
unnumbered times by many mycologists ; the ecidia have been produced 
on several species of Crataegus and possibly on the Apple and the Medlar ; 
also (spermogones only in some cases) on Cydonia, Sorbus, and Amelanchier 
—and the teleutospores on Juniperus nuna and J. oxycedrus, as well as 
on J. communis. This culture is one of the easiest to perform of all that 
are known among the Uredinales. 
The only means of checking this disease on the pomaceous hosts is by 
the removal of the affected Junipers, if they can be found. 
Disrrisution: Europe, Algeria, North America. 
2. Gymnosporangium confusum Plowr. / 
Medium Mespili DC. Flor. Fr. vi. 98. 
Roestelia Cydoniae Thiim. in Sacc. Syll. vil. 834. 
Gymnosporangium confusum Plowr. Ured. p. 232, pl. 4, f 13, 14. 
Fischer, Ured. Schweiz, p. 385, f 276; Zeitschr. f. Pflanzenkr. 
1891, i. 193, 260. Sydow, Monogr. iii. 56, f. 27. 
Spermogones. Orange-coloured. 
Ajcidiospores. AKcidia’on thickened spots, obconical or 
cylindrical, opening at the summit which is at length fimbriate, 
orange above, often surrounded by a reddish or purple, line; 
spores verruculose, pale-brown, 21—24 py. 
Teleutospores. Spore-masses at first pulvinate, dark choco- 
late-brown, almost black, then irregularly conical, 5—8 mm. 
long, chestnut-brown, swelling when moist; spores oval to 
fusiform, smooth, of two kinds, some with hyaline spore-walls 
and orange contents, tapering above, others with dark-brown 
thick walls, rounded above, about 30—50 x 20—25 fs germ- 
pores 2—4; pedicels hyaline, rather long. 
