44 Indigenous and Introduced Species. 



The hollyhocks on which this rust occurs are ornamental plants, 

 and the disease may have been spread in the ordinary course 

 of trade or exchange. The first record of a rust is by no means a 

 guide to its first appearance, for it is generally only when it has become 

 established and has proved injurious that it attracts attention. The prune 

 rust, Puccinia -pruni, which now occurs in all the States, was first observed in 

 Queensland in 1886, and was recorded for Victoria in 1883. Although con- 

 fined at first to certain districts, it has since then spread considerably, and 

 as settlement increases it becomes more widespread^ 



The flax rust, Melampsora lini, was first determined on some cultivated 

 flax from South Australia in 1889 by Galloway of the Bureau of Plant 

 Industry, U.S.A. Bolley, in a letter dated 29-th December, 1904, informs 

 me that' it is a very abundant rust upon all the wild varieties, and is always 

 more or less destructive in the flax crop. It is common enough here on 

 the native flax, and was probably introduced with flax seed. 



There are four species of Phragmidiwn in Australia a genus confined 

 to the Rose family, and only one of them is supposed to have been intro- 

 duced. Phr. subcorticium only occurs on the imported genus Rosa, and 

 was probably introduced in rose cuttings, since the mycelium of the aecidium 

 is known to winter in the stem. 



Phr. potentillae on species of Acaena was determined by Winter, and' 

 although referred by him to this widely distributed species, it is probably 

 new. Phr. longissimum was first discovered at the Cape of Good Hope, 

 and is now known to occur in other parts of Africa. Its appearance on a 

 native Rubus in Queensland would seem to support the generally accepted 

 opinion of a former land -connexion between Africa and Australia. But 

 Wallace in his Island Life offers an alternative view. " We .should prefer 

 to consider the few genera [of plants] common to Australia and South 

 Africa as remnants of an ancient vegetation, once spread over the Northern 

 Hemisphere, driven southward by the pressure of more specialised types 

 and now finding refuge in these two widely separated southern lands." 

 From the shape and arrangement of the teleutospores and their germination 

 immediately on ripening, this species stands apart from ithe others belonging 

 to this genus, and Dietel 13 draws the conclusion that it separated at a very 

 early period from the common stem of the genus Phragrnidium, a conclusion 

 which harmonizes with the views of Wallace. 



But the most interesting case of distribution is that of Phr. barnardi, 

 which is not confined to Australia as was formerly believed. Quite the 

 same type has now been found in Japan on the same host-plant (Rubus 

 parvifolius)^ and, according to Dietel 13 , it is simply a variety of the Aus- 

 tralian species, having fewer cells in the teleutospore, and therefore dis- 

 tinguished as variety pauciloculare. 



A number of plants are common to Eastern Asia and Australia, and 

 R. parvifolius is included by the late Baron von Mueller in a list of plants 

 which extend from Eastern Australia to Japan. There are various ways 

 in which the species may have attained to its present wide distribution, 

 which is given as Malaya, China, Japan, and Australia. Birds may have 

 carried the seeds, and with it some attached spores of the fungus to the 

 Asiatic continent, or inversely from Japan to Australia. There is also the 

 possibility of a former land-connexion between Australia and Asia, which 

 is assumed by -the zoologists, and ait that time the two forms of Phr. bar- 

 nardi may have existed. The flora of Japan, like that of Australia, is 

 regarded as being of the same character as that of the Tertiary period, so 

 that the ^yild raspberry and allied plants had plenty of time to spread 

 from a point to the north of both Australia and Japan, carrying with them 

 to their new homes, the rusts already developed upon them. 



