Hosts : Deyeuxia Forsteri Kunth. On leaves and culms. Herb. No. 739. II, III. Lake Harris track, Otago, 650 m., W. D. Reid! 6 May, 1921. Triticum vulgare Vill. Herb. No. 1268. Ruakura, Auckland, A. W. Green! 9 Jan., 1922.

0. Spermogones epiphyllous. crowded in small groups, seated on inflated areas, immersed, honey-coloured.
1. Aecidia hypophyllous and petiolicolous, crowded in small groups up to 5 mm. diam., seated on somewhat inflated areas, orange. Peridia cylindrical, up to 2 mm. high, 0.1-0.3 mm. diam., margins slightly expanded, not revolute, white, finely laciniate. Spores globose or elliptical, 18-28 X 15-23 mmm.; epispore hyaline, densely and minutely verruculose, 1-1.5 mmm. thick, cell-contents granular, yellow.
II. Uredosori amphigenous, scattered or crowded, seated on pallid spots, linear, 0.5-1 mm. long, orange-yellow, pulverulent, surrounded by the ruptured epidermis. Spores subglobose, elliptical or obovate, 28-32 X 23-26 mmm.; epispore hyaline; finely and closely echinulate, 1-1.5 mmm. thick, cell-contents granular, orange-yellow; germ-pores scattered, 6-8, conspicuous.
III. Teleutosori amphigenous, chiefly hypophyllous, and culmicolous, scattered or crowded, often confluent, linear, 0.5-2 mm. long, dark chestnutbrown, pulvinate, compact, long covered by the epidermis. Spores ellipticoblong or subclavate, 40-60 X 15-20 mmm.; apex acuminate, bluntly rounded, or truncate, thickened up to 10 mmm., darker in colour, base attenuate, basal cell narrower, longer, and lighter in colour than the upper; slightly constricted at the septum; epispore smooth, chestnut-brown, 1.5-2 mmm. thick in the upper cell, 1-1-5 mmm. in the lower; pedicel persistent, hyaline, tinted beneath the spore, short, up to 15 X 6 mmm.; germ-pore of the upper cell apical, obscure, basal pore immediately beneath the septum, obscure.
X. Mesospores not uncommon, elongate-elliptical, up to 40 X 12 mmm.

Distribution: Europe; Asia Minor; Japan; North and South America; Australia.

One host is indigenous and widely spread throughout; it occurs also in Australia and Tasmania (Cheeseman, 1906, p. 868). The other is widely cultivated throughout the world.
Arthur has by a long series of cultures shown that this species consists of numerous races formerly considered to be distinct species. These so-called species were separated on account of the fact that the aecidia were known to occur on several hosts; but until the necessary cultural work had been performed by Arthur apparently no attempt had been made to ascertain whether these races were in any way associated. His arrangement of these races under the one species is followed here, and the synonymy, given above taken from his paper in North American Flora, vol. 7, p. 333, 1920. In this paper he records fifty-nine aecidial hosts (all belonging to the family Ranunculaceae) and ninety-three telial hosts belonging to the Poaceae.
The genus Rostrupia Lagerh. was based on abnormal 3-4-celled forms of the teleutospores of this species.
It may be mentioned that Arthur includes here P. agropyrina Erikss. and P. triticina Erikss., two races formerly included under P. dispersa Erikss. et Henn. Although not sufficiently differentiated to separate as distinct species, these two forms may in the uredo stage be separated on account of the ferruginous colour of the uredosori.