InU fdiution. 



CHAPTER I. 



Introduction. 



Every fanner is more or less familiar with tlie ordinary smuts, which are 

 so frequently seen in our cereal crops, either converting their ears into a sooty 

 mass, or indicating by their foetid odours, especially when crushed, the pre- 

 sence of a disagreeable and destructive parasite. But the}^ are by no means 

 confined to these hosts, for they are very common on grasses generally and 

 occur on a number of flowering plants. Only one smut has been found out- 

 side of this group, on the capsule of a Sphagnum, or peat-moss. It is in reality 

 onlv the spores which appear on the surface, as the body of the plant which 

 produces them is deeply seated in the tissues. The spores are formed in all 

 the different organs of the plant, generally where food material is most plen- 

 tiful, but usually are confined to one definite position, which is characteristic 

 for the species. The grains and seeds are favourite spots for the develop- 

 ment of the spores, since the supply of food is not only abundant and choice, 

 but they are also in such an exposed position that they are readily distributed. 

 They reach the healthy grain in various ways, and there is an evident advan- 

 tage in being carried and sown with the seed. One would hardly expect 

 to find smut spores produced at the collar of woody trees, but, according to 

 . Vuillemin ^ , this is the case with at least one species which produces woody 

 tumours on Eucalypts. The species which is known as Ustilago vriesiana 

 occurred in the Botanic Garden, Amsterdam, on various species of Eucalypts, 

 including E. globulus. E. amygdalina, E. rostrata, E. leucoxylon, and E. macror- 

 rhijncha and there is every probability that it exists in Australia, although 

 hitherto overlooked. It is the only Ustilagine known to produce a woody 

 tumour, and its spores, formed in cavities between the wood and the bark, 

 are described as violet-brown, oval, smooth, measuring 7-9 x 5-7 j-i. In one 

 of the smuts attacking maize the spores may be produced on the adventitious 

 roots above ground, stems, leaves, or inflorescence and the Flag Smut of wheat, 

 as the name indicates, is usually confined to the leaves. Even the anthers 

 of the flower may be invaded by a smut, as in the case of the Carnation and 

 other species of that family, where the spores of the smut replace the pollen 

 of the flower and are discharged just like the pollen. 



The smut, as is the case with other parasites, may stimulate the part at- 

 tacked and cause an abnormal growth, so that the plant endeavours to meet 

 the extra demands made upon it by the fungus. The smut-boils of the Maize 

 are well-known examples, audit is interesting to note that they contain pro- 

 bably the same alkaloid as the Ergot, and the fluid extract is used in a similar 

 manner. Not only is there a smut used in medicine, but there is one used 

 for food, viz., Ustilago esculenta, P. Henn. Only the upper extremity of the 

 shoot of Zizania is smutted, and the swollen and deformed portion is eaten 

 in China as a vegetable. 



Wherever the spores are produced they are in such countless numbers 

 that a supply for next season is usually assured, and if tlu> conditions are 

 favorable for their germination at the proper time, infection as a rule occurs, 

 and the smut is propagated. 



The infection tube can only peuetrat(> the lio^t-plaut and hccomc para- 

 sitic at a spot where the tissue is young and tcndci'. This may he in the 

 young seedling, leaf, or stem, but it nui\- also occur in tlic llowering stage 

 when the young ovary is just forming. 



u r ^talt Colltgf 



