IVRI B 407.pdf

lNTR01>UCT10N.
difficult or impossible to determine whether or not a fungus has been introduced.
There are a considerable number of introduced flowering plants in India, * especially
cultivated plants and weeds, and with some of these rusts have certainly immigrated.
These introduced rusts are the most likely to be collected. If allowances be made for
this clement in thc Indian flora both of hosts and rusts, the figures for distribution
of the flowering plants and for the rusts become more similar, as indeed we should
anticipate from the restricted and obligate parasitism of the latter.
Nevertheless, further study may indicate rather definitely that speci€s of rusts
have, on the average, wider ranges of distribution than species of Phanerogams.
1£ we take again the rusts of the British Isles and of India, we may note that of the
252 species in the British Isles, 59, or 23·4 per cent. have been Tecorded also in India.
And even more striking is the comparison between the rusts occurring in India and
in Manitoba. Only a few cultivated plants and weeds, and a few species of indigenous
Phanerogams, are common to these two areas which are so nearly antipodean,
and yet 28 species of rusts are common to both: over 7 per cent. of the known Indian
rusts occur in Manitoba, and some 21 per cent. of Lhe 134 rusts known in Manitoba,
occur also in India. Nine t of these 28 rusts were probably introduced into onc or
both areas, but the other 19 species t appear to be native to both. It should be
remarked that of these 19 species, three, (Puccinia andropogonis, Uromyces P1"Oeminens,
and U. scirpi) are recorded with considerable doubt from India. All of
these species apparently native to both India and Manitoba, with the exception of
U?'omyces jab,'[c, have been found only in the colder, Himalayan region of India.
Puccinia circaeae, P. polygoni-mnphibii, and Ummycps polygoni utilize the same
specics of hosts in both countries, as does U.jabae in part; the remainder apparently
utilize different but related hosts in the two countries.
Species of certain non-parasitic groups of fungi certainly have a very wide distribution:
thus, of the 69 names that have been applied to Discomycctcs from
India, over 40 per cent. are found in European lists, and 23 per cent. in the Manitoba
list; of the 75 recorded Gasteromycetes, 20, or 27 per cent. are known in
England. It is to be expected that fungi which develop upon leaf mould or decaying
wood may find a suitable substratum in almost any country, but we cannot
pursue our comparisons far, because the data are too indefinite. Petch § has
presented a discussion of the uncertainty involved in applying the names of European
fungi to specimens from thc tropics, in which he concludes that, in general, the
• Profpssor L. A. Kenoyer, Plant Life of British Innia, Sci. Monthly, XVIII, p. 58, 1924, states
that "The present Indian flora contains many introduced plants, American ones being especially
prominent." .
t Jj[elampsora lini, Puccinia CO'rOWlta, P. g.raminis, P. lolii, P. sO'rghi, P. anomala, P. taraxaci, P.
triiicina, and Uromyc8s trifolii. The names used in the Manitoba list are in a few instances different
from those used here.
t Phragmidium disciflorum, P. potentillae, Puccinia absinthii, P. andropogonis, P. caricis,
P. caricis.asleris, P , circaeae, P . hieracii, P. menthaR, P. phragmitis, P. pimpine/lae, P. polygoni.amphibi.,
P. punctatu, P. violae, Pucciniastrum agrimoniae, Uromyces faoae, U. polygoni, U. pro_min en .. , and U.
8cirpi.
§ Petch, T. European fungi in the tropies.-Trans. Brit. Myc. Soc., III, pp. 340·347. 1912.