ON COMPOSITE 147 



21. Puccinia Lapsanae Fckl. 



JEcidium Lapsanae Schultz, Prod. Flor. Starg. p. 454. Cooke, Journ. 

 Bot. ii. 38, pi. 14, f. 2 ; Handb. p. 543 ; Micr. Fung. p. 198. 



Trickobasis Lapsanae Cooke, Micr. Fung. p. 224. 



Puccinia iMpsanae Fckl. Synib. Myc. p. 53. Cooke, Micr. Fung, 

 p. 207. Plowr. Ured. p. 149. Sacc. Syll. vii. 607. Sydow, 

 Monogr. i. 112. Fischer, Ured. Schweiz, p. 203, f. 159. 



Spermogones. Crowded in little clusters, epiphyllous, honey- 

 coloured. 



jEcidiospores. vEcidia amphigenous, somewhat crowded on 

 large, roundish, purple spots, fiattish, with torn white rerlexed 

 margin ; spores subglobose or ovate, nearly smooth, orange, 

 16—21 x 13—17 ft. 



Uredospores. Sori amphigenous, very minute, round, very 

 numerous, often confluent, pulverulent, chestnut- 

 brown ; spores globose to ovate, delicately echinu- 

 late, pale-brown, 17 — 22 x 15 — 18 /n, with two 

 germ-pores. 



Teleutospores. Sori amphigenous, minute, 



scattered, numerous, pulverulent, blackish-brown; Fig 99 F 



spores ellipsoid or ovate, rounded at both ends, Lapsanae. 



. Teleutospore. 



not thickened above, scarcely constricted, very 



delicately punctate, chestnut-brown, 22 — 33 x 17 — 26 /x; pedi- 

 cels hyaline, slender, short, often oblique. 



On leaves and stems of Lapsana communis. Very common. 

 iEcidia, March — May; uredospores, April — June; teleutospores, 

 June — September. (Fig. 99.) 



The aecidium of this species shares with those on Ranunculus Fiearia 

 and Potentilla Fragariastrum the distinction of being the earliest Uredine 

 to make its appearance in the spring. It may be found on the young 

 leaves of the seedlings almost as soon as they are formed. Plowright 

 demonstrated (Expt. 499, May, 1885) that all three spore-forms belong to 

 the same life-cycle. The mycelium of the aecidia, when occurring on the 

 petioles, causes them to become pale and swollen ; on the leaves it often 

 produces conspicuous purple spots which bear the spermogones on the 

 upper surface. 



Distribution : Europe, Syria, Japan. 



10—2 



