ON COMPOSITE 145 
19. Puccinia obtegens Tul. 
Caeoma obtegens Link, Obs. ii. 27. 
Trichobasis suaveolens Lév.; Cooke, Handb. p. 530; Micr. Fung. 
p. 226, pl. vii. figs. 151—3, 
Puccinia obtegens Tul. Ann. Sci. Nat. ser. 4, ii. 87 (1854). Sydow, 
Monogr, i. 53, 
P. suaveolens Rost. Bot. Zeit. 1874, p. 556. Plowr. Ured. p. 182 p.p. 
Sacc. Syl. vii. 633 p.p. Fischer, Ured. Schweiz, p. 219, f. 172. 
Spermogones. Chiefly hypophyllous, a few epiphyllous, 
crowded, covering the whole surface of the leaf, of a bright 
honey-yellow colour and a pleasant smell. 
Uredospores. Primary sori hypophyllous, occupying the 
whole surface of the leaf, minute, crowded, often confluent, 
pulverulent, reddish-brown, then darker; secondary, more scat- 
tered; spores globose to broadly ellipsoid, echinulate, pale- 
brown, 21—28 », with three irregularly placed germ-pores. 
Teleutospores. Sori similar, always dark-brown; spores 
ovate to ellipsoid, rounded at both ends, or 
somewhat tapering below, not thickened 
above but with a low flat pore-cap, hardly 
constricted, delicately verruculose, brown, 
26—42 x 17—25 py; epispore thin; pedicels 
hyaline, thin, short. 
Fig. 97. P. obtegens. 
On Cirsium urvense (Carduus arvensis). Teleutospores, 
Very common. (Fig. 97.) 
The life-history of this species is peculiar. In spring the mycelium 
permeates the host in every part. The affected plants can be recognised 
immediately by their pale-green colour and spindly appearance; they 
never flower. The spermogones are first seen towards the end of April, 
and are easily detected by their bright colour, and their strong perfume, 
resembling that of privet-flowers; the uredospores follow on the same 
leaves during May. From these primary uredospores, a second generation 
arises on other plants about July, and forms secondary uredospores and 
tcleutospores in sori which are more scattered, never confluent, and 
darker brown. This generation is not accompanied by spermogones, 
The mycelium of these sori is localised to the infected spots and the host 
does not suffer so severely. The sori of the primary uredospores rarely 
bear a few teleutospores intermixed, but the secondary sori abound with 
them from September to November, and it is from the germination of 
G. U. 10 
