CHAPTER VII 



HEMIBASIDIOMYCETES 



USTILAGINALES 



THE Ustilaginales, Brand fungi, Smuts or Bunts, constitute a group of some 

 4O> obligate parasites on the higher plants, giving rise in the tissues of the 

 host to characteristic, usually dark-coloured resting-spores, the brand-spores, 

 teleutospores or chlamydospores. These are developed in considerable 

 quantities, either singly, in pairs, or in clusters known as spore-balls, and 

 when ripe break through the host tissue, forming a pustule or sorus. No 

 distortion of the host is caused during the period of vegetative growth, but 

 in preparation for the formation of spores very considerable hypertrophy 

 may be induced. 



Ustilago Treubii on the stem of Polygonum chinense in Java causes the 



formation of elaborate galls (fig. 146) 

 provided with vascular tissue and 

 growing by means of a cambium; 

 Ustilago Maydis produces whitish 

 swellings and blisters, often as large 

 as a fist, on the stem, leaves, roots, and 

 especially the flowers of Zea Mays; 

 and Urocystis Vzolae deforms the stems 

 and leaves of various species of Viola. 

 Several other smuts develop their 

 spores in the ovary of the host plant, or 

 infect the stamens, filling the anthers 

 with spores and benefiting by the 

 means of distribution provided for the 

 pollen. Ustilago antheraruml even 

 induces development in the staminal 

 rudiments of the normally pistillate 

 flowers of Lychnis dioica. The stamens 

 formed undergo dehiscence as usual 

 and differ from those of the male 

 flowers only in the presence of fungal 

 spores instead of pollen in their anthers. 

 In all these cases and in most of the Ustilaginales spore- formation is 

 strictly localized, but in the genus Entyloma and its allies spores may be 

 formed at almost any point. 



1 Ustilago antherarum (DC.) Fr.= Ustilago violacea (Pers.) Fuck. 



Fig. 146. Ustilago Treubii Solms ; stem of 

 Polygonum with " fruit gall," nat. size ; after 

 Solms Laubach. 



