386 



THE FUNGI WHICH CAUSE PLANT DISEASE 



transfer to various cereals which it will not attack directly. That 

 such transfers take place in nature to some extent is probable.™' 



P. poarum Niess occurs on bluegrass. 



P. malvacearum Mont.^*^'''* 



III. TeUa grayish-brown, compact, round, pulvinate, elon- 

 gate on the stems, scattered, seldom confluent, pale reddish- 

 brown. Spores fusiform, attenuated at both extremities, apex 

 sometimes rounded, constriction slight or absent, apical thickening 

 slight, smooth, yellow-brown, 35-75 x 15-25 m- Pedicels firm, 

 long, sometimes measuring 120 ai. 



A lepto-puccinia on three species of Althea, seven of Malva, two 

 of Malope; particularly serious on the hollyhock. A native of 

 ChiU, it was first known as a pest in Australia; soon afterward in 

 Europe. It seems to have entered the United States sometime 

 prior to 1886 and is now almost imiversal. The teliospores ger- 

 minate immediately in suitable environment, mainly from the 

 apical cell, or may remain alive over winter and originate the 

 spring infection. The myceliiun also hibernates in young leaves. 

 Mesospores are common. 3 to 4-celled teliospores are also met. 

 P. heterogena Lag. is also described on 

 hollyhock from''"' South America. 

 P. chiysanthemi Roze.^"^ 



II. Uredinia chocolate-brown, single or in 

 circular groups, hypophyllous, rarely epiphyl- 

 lous. Spores spherical to pyriform. ' Mem- 

 brane spiny and with three germ pores, 17-27 x 

 24-32 M. 



III. Telia dark-brown hypophyllous. Telio- 

 spores rarely in uredinia, dark, obtuse, apex 

 thickened, membrane thick, finely spiny, 20- 

 25 X 35-43 II. Pedicel 1-1^^ times the spore 

 length. 



On cultivated Chrysanthemum. Occasion- 

 ally urediniospores like the other uredinio- 

 spores in all other respects but 2-ceIled are 

 found; a habit unique with this rust. In many places uredinio- 

 spores may be produced continuously and teliospores be but rarely 

 seen, thus in America only urediniospores have been found. It was 



Fio. 279.— P. helianthi, 

 uredinio- and telio- 

 spores. After Cobb. 



