Tapper first collected it on the female. The smut is less con- 

 spicuous on the male inflorescences, nor is so large a spore 

 mass formed, which may account for it being overlooked by 

 previous collectors. 



Pathological Changes in the Host. 

 The inflorescences of the "spiny rolling grass" are common 

 and conspicuous objects along the coastal dunes of South 

 Australia. The salient features of the normal inflorescences 

 will first be described, then the pathological changes noted. 



The normal male inflorescence is a roughly spherical 

 head, about 15 cms. in dianieter, borne on a stout upright 

 stem. It consists of an aggregation of stiff secondary axes, 

 each arising in the axil of a bract, upon which the spikelets 

 are borne. Below the terminal head there is usually one, 

 sometimes two, smaller lateral clusters of secondary axes. 

 Each secondary axis is a stout structure about 7 or 8 cms. 

 long, bearing a group of 10 to 20 irregularly spirally arranged 

 spikelets distributed over the middle third of its length. The 

 upper and lower portions of the axis bear no spikelets, the 

 upper part terminating in a stiff tapering spine. The spikelet 

 is composed of two sterile glumes and two flowering glumes, 

 or three sterile and one flowering glume. The flower consists 

 of glume, pale, two broad lodicules, and three stamens. The 

 axis of the flower ends abruptly with the stamens: no ovary 

 rudiment has been seen in the flowers examined. 



The smutted male inflorescences are much slenderer and 

 more diffuse (pi. i., fig. 1). The main differences are: — 



(a) Greater elongation of the internodes of the upright 

 stem. In the smutted specimens the average 

 length of internode between the terminal head and 

 the small lateral cluster, next below it, was 

 9*4 cms. as against 6' 7 cms. in healthy specimens. 

 (h) Reduction in the number of secondary axes bearing 

 spikelets in the inflorescence; an average of 16 per 

 head in the smutted specimens as against 64 in the 

 healthy specimens. 

 (c) The closer aggregation of the spikelets and an increase 

 in their number per secondary axis. 



The smutted male spikelets consist of the two sterile 

 glumes and two florets. Each has the fertile glume, pale, 

 and three stamens. No lodicules were seen (text fig. 1), the 

 anthers are about normal length, but contain no pollen, and 

 the filaments do not elongate. No ovary recognizable as such 

 is present, but the axis of the flower elongates above the point 

 of stamen insertion, producing an irregular conical mass 



