352 MELAMPSORA 
Spermogones. Epiphyllous, or a few hypophyllous, in large 
round clusters, honey-coloured. 
Aicidivspores. Ceeomata hypophyllous and on the petioles 
and stems, in clusters on pale-yellow spots, often circinate 
round the spermogones, about 1 mm. wide, often confluent in 
patches 1—14 cm. wide, bright-orange; spores roundish-poly- 
gonal or oval, 13—18x12—16y; epispore 1—l}¥ thick, 
finely and densely verruculose. 
(>) 
WA 
Fig. 263. M. Rostrupii. u, teleutospores on P. tremula; b, teleutospore on 
P, alba; c, wcidiospores on Mercurialis perennis; d, paraphyses and 
uredospores on P. tremula (one paraphysis contains the orange remains of 
the protoplasm). 
Uredospores. Sori hypophyllous, about 1 mm. wide, pulvi- 
nate, compact, causing large yellow spots on both sides; spores 
oval or sometimes roundish-polygonal, 21—25 x 14—18 1; 
epispore up to 34 thick, covered with stout rather distant 
spines; paraphyses distributed throughout the sorus, clavate or 
somewhat capitate, 50 x 15—23 yw, with a thick wall (3—6 p). 
Teleutospores. Sori hypophyllous, $—1 mm. wide, scattered 
over the whole leaf, covered by the epidermis, dark-brown ; 
spores prismatic, rounded at both ends, pale-brown, 40—55 x 
8—10,; epispore thin (1—2 ), not thickened above, without 
any evident germ-pore. 
Ceomata on Mercurialis perennis, April—June ; uredo- and 
teleutospores on Populus alba, P. tremula, and occasionally on 
other species, September and October. (Fig. 263.) 
The connection of the two forms has been shown by Rostrup, Nielsen, 
Plowright, Klebahn, Wagner, and Jacky, The teleutospores may be found 
