ON POLYGONACE.E 223 



scattered singly : those of the Puccinia are in largish orbicular clusters 

 and are rarely found singly ; if not clustered, they spread over the whole 

 leaf. In Plowright's herbarium are some leaves of Lychnis diurna, covered 

 with uredo-sori, which he mistakenly assigned to P. Lychnidearum : there 

 are no teleutospores of the latter, however, but a very few of P. Behenis 

 were found in the same sori. See under P. Lychnidearum. The circinate 

 arrangement of the sori, on paler spots, is very similar in both species. 



Distribution : Central and Western Europe. 



93. Puccinia Acetosae Korn. 



Uredo Acetosae Sebum. Plant. Sail. ii. 231. 



Puccinia Acetosae Korn. in Hedwig. 1876, p. 184. Plowr. in Trans. 



Brit. Myc. Soc. i. 57. Sacc. Syll. vii. 638. Sydow, Monogr. 



i. 581. Fischer, Ured. Schweiz, p. 134, f. 101. 



Uredospores. Sori amphigenous, scattered, minute, roundish 



on the leaves, elongated on the 



petioles and stems, soon naked, 



ferruginous-brown; spores globose 



to obovate, sparsely aculeate, 



brownish, 24—30 x 20—23 /*, with 



two (rarely three) germ-pores. 



rn j . o • • -l \ F'g- 171. P. Acetosae. 



1 eleutospores. Son Similar, but Teleutospores and uredospore. 



dark-brown ; spores ellipsoid, ob- 

 long, or subclavate, rounded at both ends or slightly attenuated 

 below, not thickened at the apex, but furnished with a broad 

 pore-cap, slightly constricted, delicately verruculose, chestnut- 

 brown, 28 — 42 x 19 — 24 yu,; pedicels hyaline, slender, deciduous, 

 as much as 35 /m long. 



On Rumex Acetosa. Maiden, Yorkshire, July 16, 1894 

 (A. W. Saunders). Ireland, co. Antrim (J. Adams), August, 

 1909. Bewdley, Worcestershire, August, 1907, etc. (Fig. 171.) 



There is no doubt that this species is often mistaken for Uromyces 

 Acetosae. In the absence of the two-celled teleutospores, which are rare, 

 it could be distinguished mainly by its smaller sori, and more spiny 

 uredospores (the spines are quite colourless). The teleutospores show the 

 delicate warts more clearly on the upper cell ; in the Bewdley specimens 

 they were perceptible only with great care. Magnus proved that this 

 species can pass the winter by its uredospores. It may be hetero3cious. 



