CARPOSPOREJE. 145 



5. Ustilagineae. The plants of this order are also 

 parasitic ; the mycelium ramifies through the tissue of the 

 host-plant, and finally produces an abundance of brown, 

 or black, thick-walled spores, which burst through the 

 epidermis. The hyphse are jointed and branching, grow 

 in the intercellular spaces, and also within the cell-cavjties 

 of their host-plants. The mycelium generally begins its 

 growth when the host-plant is quite young, and grows 

 with the latter. The spores are generally produced only 

 in some definite part of the plant, as the young flowers 

 (as in the smut of Wheat, Oats, etc.), ovaries (as in the 

 bunt of Wheat), anthers (as in the smut of Silene), etc. 

 In the smut of Indian Corn they may be formed in any 

 part of the plant. The spores germinate, so far as have 

 been observed, by producing a promycelium on which 

 several sporidia are formed, much as in the Uredinese. No 

 sexual organs have as yet been detected. Many species 

 of the genera Ustilago, Tilletia, and TJrocystis are very 

 destructive to Wheat, Oats, Corn, Grasses, Onions, etc. 



173. The large and interesting Fungi, known as Puff- 

 balls and Toad-stools, are additional representatives of the 

 Carposporese. But one kind of spores, and these non-sexual, 

 are known, and they are produced on slender out-growths 

 from the ends of enlarged cells, called haddia (Fig. 261, h) ; 

 for this reason the group is called the Basidiomycetes. The 

 mycelium is mostly saprophytic, very abundant, and from 

 it the spore-bearing growth, or sporocarp, is produced. The 

 two important orders of this class are the Gasteromyeetes 

 and Hymenomyeetes : 



I. Gasteromyeetes. The sporocarps in this order are 

 usually more or less globular. The spores are borne within 

 somewhat irregular cavities, from which they escape by the 

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