130 



MORPHOLOG Y. 



(figs. 147-150). These two forms occur on the stems, blades, 

 etc. , of the wheat, also on oats, rye, and some of the grasses. 



290. Teleutospores of the black-rust form. — If we scrape off 

 some portion of one of the black pustules (sori), tease it out 



Head of wheat showing black rust spots 

 on the chaff and awns. 



Fig. 151- 



Teleutospores of wheat rust, 



showing two cells and the pedicel. 



Fig. 152. 

 Uredospores of wheat rust, one 

 showing remnants of the pedicel. 



in water on a slide, and examine with a microscope, we will see 

 numerous gonidia, composed of two cells, and having thick, 

 brownish walls as shown in fig. 151. Usually there is a slender 

 brownish stalk on one end. These gonidia are called teleuto- 

 spores. They are somewhat oblong or elliptical, a little con- 

 stricted where the septum separates the two cells, and the end 

 cell varies from ovate to rounded. The mycelium of the fungus 



