1 1 12 THE BOOK OF GARDENING. 



species it is a wound-parasite. P. squamosus also occurs on a 

 number of trees, Maple, Oak, Mountain Ash, Horse-Chestnut, 

 and many others. The semi-circular sporophores are yellowish- 

 white on top, with darker scales (hence the specific name). 

 Then there are also the destructive and distinctive P. betulinus, 

 on Beech, and P. dryadeus, on Oak, both having hoof-like 

 sporophores, and many others. 



Polystigma rubrum. — This is a well-marked fungus attack- 

 ing Plums (both wild and cultivated), Bird Cherries, &c. The 

 leaves are frequently disfigured by somewhat roundish patches ol 

 a reddish colour, which, after a time, thicken. The disease is 

 not a virulent one, and, moreover, is easily controlled by burning 

 the infested leaves as they are shed. 



Rusts (Uredinece). — These fungi are almost as familiar as the 

 Mildews. They differ, however, from the latter in many im- 

 portant details. One is that the mycelium instead of being on 

 the outer surface is intercellular — in the leaf or bark-tissues, 

 as a rule. The life-histories of many are quite unknown, more 

 particularly those species which are hetercecious. One of the 

 best known of these Rust fungi is the Rose Rust (Phragmidium 

 subcorticatuni), whose deep yellow patches may be found alike 

 upon foliage and shoots of garden and wild Roses. Another 

 familiar species is that causing Rust of Wheat (Puccinia graminis), 

 a hetercecious species whose aecidium-form is familiar to gardeners 

 by reason of the orange-yellow spots on Berberis in spring. 

 This species develops both uredospores and teleutospores upon 

 wheat and other cereals. The former are bright orange-yellow, 

 and appear in summer, and the latter are dark brown, with 

 a harder coat, and are associated with autumn. The uredospores 

 germinate readily in summer as soon as ripe; but the teleuto- 

 spores are for the purpose of carrying the disease over the time 

 when the host-plant is resting. 



Two other examples of the Rusts may be instanced in the 

 • injurious Hollyhock Fungus {Puccinia malvacearum) and the 

 Raspberry Rust (Phragmidium rubi-idcei). Weak Bordeaux 

 Mixture is useful in both the aecidium and uredospore con- 

 ditions ; but the teleutospores, which are in the soil, are difficult 

 to reach. Quicklime, where it can be applied with safety to the 

 roots, might be useful; while the burning of all leaves, fruits, 

 &c, from infested plants will also help to lessen the attack the 

 following season. In the case of hetercecious species like 

 Puccinia graminis, whose aecidium-stage, as previously stated, 

 is passed on Berberis ; or Gymnosporangium sabince (destructive 

 to Pear foliage), and whose teleutospore stage is passed upon the 

 Common Juniper (Juniperus communis) and other species, care 

 should be taken to uproot and destroy both the Barberry and 

 the Juniper if they can be traced, often a matter of great 



