RELATIONSHIPS WITHIN THE SUBCLASS TELIOSPOREAE 423 



show at their base monocaryon cells, a little further up cells with several 

 nuclei, followed by a series of dicaryon cells, while the upper portion con- 

 sists of cells each with a single diploid nucleus. These, according to Kil- 

 lian, are the cells which correspond to the teliospores of the Ustilagin- 

 aceae. In them the nucleus undergoes two divisions and the four nuclei 

 pass out into the sporidia which bud out of the teliospores. The latter may 

 remain attached, so that the upper portion of the sporogenous hypha 

 shows teliospores with sporidia in various stages of development, or the 

 teliospores may break apart before the sporidial development is com- 

 pleted. The sporidia may remain one-celled or may become two-celled by 

 the formation of a septum. In their germination they may bud like yeasts 

 or form germ tubes. The true relationship of this family is not a matter of 

 agreement among mycologists. Fischer and Killian incline to the idea of 

 kinship with the Ustilaginaceae in some of which (e.g., Sphacelotheca) a 

 peridium of hyphal tissue surrounds the sporogenous part of the sorus. 

 The budding of the sporidia from the teliospores instead of the formation 

 of typical promycelia caused Killian to refer to the somewhat similar case 

 in Ustilago longissima referred to previously in this chapter. Fischer 

 (1922) recognized two genera: Graphiola, with bundles of sterile hyphae 

 among the sporogenous hyphae, the latter separating into their individual 

 cells at maturity, and Stylina which lacks the sterile hyphae and whose 

 sporogenous hyphae do not separate into individual cells. He described 

 the four species of Graphiola studied by him and the one species of Stylina. 



Relationships Within the Subclass Teliosporeae 



It is very apparent that there is not a very close relationship between 

 the more highly developed Uredinales and Ustilaginales. In vegetative 

 structures the similarities are greater, the mycelium in both orders being 

 intercellular with nucleated haustoria. Both types of mycelium are 

 present, monocaryon and dicaryon, although the former may have a 

 very brief life, especially in the parasitic life of the Ustilaginales. Eventu- 

 ally in both orders the dicaryon mycelium produces special cells, the 

 teliospores, within which the nuclei unite to form a diploid nucleus. This 

 nucleus undergoes two meiotic divisions to form four haploid nuclei 

 which apparently in both Rusts and Smuts are two of one sexual phase 

 and two of the other. The meiotic divisions may occur in the teliospore 

 but most often occur in the promycelium. In Ustilaginales the dicaryon 

 phase of the mycelium frequently bears clamp connections but these have 

 been demonstrated rarely in the Uredinales. In the sexual reproduction 

 the Ustilaginales produce no definite male gametes. Any two cells of 

 opposite sexual phase may unite to initiate the dicaryon phase, be it near- 

 by promycelial cells, sporidia, conidia, or mycelia. In the Uredinales two 

 mycelia of opposite sexual phase may diploidize one another when they 



