1 62 Ustilago. 



Polygonum. 

 18. Ustilago utriculosa (Nees) Tul. 



Tulasiie, Ann. Sci. Nat. Bot. III., p. 102 (1847). 

 Cooke, Hanclb. Austr. Fung., p. 326 (1892). 

 Brefeld, Unters. Gesammt. Mvk. XII., p. 139 (1895). 

 Sacc. Syll. VII., p. 476, (1888). 



Sori inside floral envelopes, causing the blossoms to become swollen, 

 dark-violet to purplish, powdery. 



Spores globose or subglobose, occasionally elHpsoid, transparent, 

 violet, reticulated with verv high ridges which form meshes 2-3 jx 

 wide, 10-13 /» diam. or 11-13 x 8-11 /.. 



On Polygonum minus Huds. 



Victoria^ — Near Melbourne, June, 1884 (Reader). Tambo River, 



Feb. (National Herbarium). Casterton, Dec, 1908 (Reader). 

 Queensland— (Bailey, No. 59). 



On Polygonum frostratum., R. Br. 



victoria— Dimboola, March, 1898 (Reader). 



On Polygonum hydropiper L. 



Victoria— Tinandra, May, 1909 (Whittekers). 



The Queensland specimen was labelled Sphacelotheca hydropiperis. The 

 swelling of the ovaries and the dark purple spore-masses are very 

 characteristic. 



Spore formation. — A cross-section of the ovary shows that the spores 

 originate from hyphae adjoining the vascular bundles, where they are seen 

 as minute colourless specks, gradually acquiring a round form and a netted 

 epispore, with the development of a violet colouration. 



Germination. — This has been described and illustrated by Brefeld^. 

 The spores do not germinate, as a rule, in the autumn when they are formed, 

 but in the following summer, after lying on damp earth. In water they pro- 

 duce a triseptate promycelium, which soon gives rise to lateral and terminal 

 elliptical conidia. These become detached and again produce smaller conidia 

 without further development. In a nutritive solution, there is a more 

 luxuriant formation of conidia, with unlimited capacity for sprouting in a 

 yeast-like manner. Neither fusion of the conidia nor their germination 

 has been observed. 



Spores from a specimen of Polygonum hydropiper L., obtained in May, 

 were placed in tap Avater towards the end of September. In two days they 

 germinated freely, and in three days the great majority had germinated. The 

 promycelium was generally three septate, 3-4 /t broad, and branches were 

 frequently produced beneath the septa, the terminal segment often giving 

 rise to a slender elongated filament. Conidia were produced both laterally 

 and terminally, but the formation of branches from the segments of the pro- 

 mycelium was more common. They generally arose from the basal and 

 terminal segments and reached a length of 60 f/, while the promycelium itself 

 was only 16 ^i on an average. 



(Plate XXXII. 



