204 INJURIOUS INSECTS AND FUNGI. [Dec, 1894. 



Fig. 2. 



X "==1- o o 



A. Uredospores. B. Teleutospores (^x 400). 



The fungus Uromyces hetce, Link., belongs to the large group 

 of fungi known as Uredinece, and to the division Aitteuuro- 

 myces, ov having all the spore- forms on the same host plant. 

 The dangerous Fuccinia graminis, causing wheat rust, belongs 

 to this group also, but there are important distinctions in the 

 life history of these two fungi. In the case of Puccinia 

 graminis the oecidium stage, and the subsequent stages of 

 uredospore and teleutospore, are passed upon different hosts; 

 the oecidinAn stage upon the barberry, and the two latter 

 stages upon corn plants. 



The three stages of Uromyces betm are passed upon varieties 

 of the genus Beta, plants of varieties of Beta vulgaris and Beta 

 raaritima. (sea beet), as the garden beet, sugar beet, and mangel 

 wur£el. The oecidium or cluster-cup," stage is to be found in 

 the spring upon the leaves and stalks (petioles), of seed-beet and 

 seed-mangel plants ; that is plants which have been put out in 

 the autumn to stand during the winter for seed. Mr. Plowright 

 states that he found the oecidium of Uromyces hetce upon the sea 

 beet. Beta maritima, in April. 



The oecidiospores are orange- yellow, smaller than the uredo- 

 spores and teleutospores, and are arranged in chains. They ger- 

 minate and form mycelia in the leaf tissues, under the epidermis. 

 From the mycelia suckers (haustoria) are formed, which exhaust 

 the juices of the leaves for their own food supply. After a while 

 hyphre, or branching filaments, are sent forth from the mycelial 

 centre ; upon the end of each of the hyphse a spore is formed. 

 The spores by their pressure rupture the epidermis, or skin, of 

 the leaf, as shown in Figure 1, and fall to the ground after a time, 

 or on other parts of the plant, or are carried by the wind to infect 

 other plants. These spores are larger than the oecidiospores ; 

 they are ovate, unicellular, pale brown, or light sherry-coloured, 

 and echinulate, or having points or prickles, as shown in 

 Fig. 2a. In suitable conditions there may be several generations 

 of uredospores, but as the autumn approaches another kind of 

 spore makes its appearance, as in the case of Puccinia grami- 

 nis. This is the teleutospore (Fig. 2b.) which is more elliptical 

 in shape than tlie uredospore, arid is unicellular and slightly 



