ORDER USTILAGINALES (tHE SMUTs) 419 



in the leaves of various species of Carex. In Sorosporium, Tolyposporium 

 and other genera the teliospores are united into more or less firm balls. 

 They are largely parasitic on grasses. (Fig. 141.) 



Family Tilletiaceae. Promycelium nonseptate, the sporidia being 

 formed at its apex in a dense cluster or in a whorl. The number of sporidia 

 varies usually from 4 to 30-50, but in Neovossia indica (Mitra) Mundkur 

 may reach 150 (Mundkur, 1943). The teliospores arise as terminal cells of 

 hyphae or of short lateral branches or as intercalary cells. The two nuclei 

 unite and the cells round up and secrete a heavier wall which may be dark 

 or light in color and is smooth or more often reticulately marked or spiny. 

 The teliospores occur as single spores in a dusty mass or united into small 

 or large balls of spores with or without a covering or a core of sterile cells. 

 These spores or spore balls may escape as a powdery mass or remain 

 within the host tissue. The sporidia are fusiform or sickle-shaped and are 

 inclined to unite by twos while still attached to the promycelium or after 

 they have been shot off. A binucleate conidium may be produced directly 

 from a pair of united sporidia. As in the preceding family the sporidia 

 appear to be of at least two sexual phases. From one of the sporidia of the 

 united pair a germ tube of dicaryon cells may grow out and infect the host 

 plant. Infection may take place from a dicaryon conidium set free from 

 the united sporidia or arising on a dicaryon mycelium. The sexual cycle 

 which is initiated by the fusion of the sporidia is completed by the union 

 of the nuclei in the teliospore. (Fig. 142A, B.) 



About 13 genera and over 250 species are recognized in the family. 

 Tilletia (about 40 species) corresponds to Ustilago in producing its telio- 

 spores as single cells in a powdery mass. T. caries (DC.) Tul. (T. tritici 

 (Bjerk.) Wint.), with rough teliospores and T. foetida (Wallr.) Liro {T. 

 levis Ktihn), with nearly smooth teliospores, cause stinking smut or bunt 

 of wheat. Flor (1932) has crossed these two species by picking off single 

 sporidia and allowing the two monocaryon myceha produced from them 

 to unite. These hybrid mycelia were used successfully to inoculate wheat 

 plants. The teliospores produced on these plants resembled most closely 

 those of T. foetida. Certain species of Tilletia have been described from 

 the capsules of Sphagnum and Anthoceros, both in the Bryophyta, but 

 Bauch (1938) studying T. sphagni Nawaschin has demonstrated that it 

 does not belong to this order, the supposed teliospores actually represent- 

 ing the conidial stage of Helotium schimperi Naw., one of the Pezizales. 



Entyloma produces its teliospores singly and in the tissues of the host 

 from which they do not escape as a powdery mass, but germinate within 

 the host sending their elongated promycelia out through the epidermis 

 and forming the sporidia externally. Conidia are also formed on conidio- 

 phores which emerge through the stomata. Kaiser (1936) observed clamp 

 connections on the mycelium of E. calendulae (Oud.) de Bary. Frequently 



