ON MALVACEAE 



207 



Fig. 154. P. Malvacearum. 

 Teleutospores and meso- 

 spore. 



On many species of Malvaceae (of the subfamily Malveae), 

 especially on Malva moschata, M. silves- 

 tris and Althaea rosea. Very common. 

 May — October (also in April and Novem- 

 ber). (Fig. 154.) 



This is one of the most noticeable of the 

 Uredinales. It is truly plurivorous ; so far 

 from being confined to a species, it is not even 

 confined to a genus. In botanic gardens, where 

 species of the family Malvaceae are grown, side 

 by side, in the same plot, the disease can be 

 seen to spread to plants of all the allied genera 

 — Malva, Lavatera, Althaea, Kitaibelia, Malope, 

 Abutilon, Sida, Sidalcea, Anoda, Malvastrum, 

 etc., have been recorded. A list containing 

 many (nearly forty) species of these genera is 

 given by Sydow, to which more are added by 

 Fischer, Mc Alpine, and Dandeno. On all these 

 it appears to be identical ; artificial infections 

 have proved that it can be transferred from 

 Malva to Althaea, and vice-versd. 



It was first made known in 1852 by Montague from a specimen found 

 in Chili. It was observed in Australia in 1857 (McAlpine). In Europe it 

 appeared in 1869, in South Africa in 1875, and it is now spread all 

 over the world. It is believed that Chili was its native home ; the 

 rapidity of its distribution to other countries has few or no parallels among 

 plant diseases. 



It has been proved by many experimenters that it produces only the 

 one kind of spore, which is capable of germinating at once when mature, 

 though some can hibernate. It is a disputed point whether the mycelium 

 can pass the winter in the plant or in the seed : the balance of evidence 

 goes to show that fresh infections arise each year by the germination 

 of over-wintered teleutospores, which can be found on all green parts, even 

 on the fruits. See p. 48. 

 I 



79. Puccinia Pruni-spinosae Pers. 



jEcidium punctatvan Pers. in Uster. Annal. Botanik, xx. 135. Plowr. 



Ured. p. 268. 

 JE. quadrifidum DC. Flor. fr. vi. 90. Cooke, Handb. p. 536 ; Micr. 



Fung. p. 194. 

 Puccinia Pruni-spinosae Pers. Syn. p. 226 (1801). Sydow, Monogr. i. 



484. Fischer, Ured. Schweiz, pp. 157, 547, ff. 21, 122, 340. 



McAlpine, Rusts of Australia, p. 171, f. 83—6 and pi. D, f. 19—20. 



