ou can remember any cases of one introduced species beating out or
prevailing over another, I should be most thankful to hear it. I believe
the common corn-poppy has been seen indigenous in Sicily. I should like
to know whether you suppose that seedlings of this wild plant would
stand a contest with our own poppy; I should almost expect that
our poppies were in some degree acclimatised and accustomed to our
cornfields. If this could be shown to be so in this and other cases, I
think we could understand why many not-trained American plants would not
succeed in our agrarian habitats.

LETTER 343. TO J.D. HOOKER.

(343/1. Mr. Darwin used the knowledge of the spread of introduced plants
in North America and Australia to throw light on the cosmic migration
of plants. Sir J.D. Hooker apparently objected that it was not fair
to argue from agrarian to other plants; he also took a view differing
slightly from that of Darwin as to climatal and other natural conditions
favouring introduced plants in Australia.)

Down, January 28th, 1859.

Thanks about glaciers. It is a pleasure and profit to me to write to
you, and as in your last you have touched on naturalised plants of
Australia, I suppose you would not dislike to hear what I can say
in answer. At least I know you would not wish me to defer to your
authority, as long as not convinced.

I quite agree to what you say about our agrarian plants being accustomed
to cultivated land, and so no fair test. Buckman has, I think, published
this notion with respect to North America. With respect to roadside
plants, I cannot feel so sure that these ought to be excluded, as
animals make roads in many wild countries. (343/2. In the account of
naturalised plants in Australia in Sir J.D. Hooker's "Introductory Essay
to the Flora of Tasmania," 1859, page cvi, many of the plants are marked
"Britain--waste places," "Europe--cornfields," etc. In the same list
the species which have also invaded North America--a large number--are
given. On the margin of Darwin's copy is scribbled in pencil: "Very
good, showing how many of the same species are naturalised in Australia
and United States, with very different climates; opposed to your
conclusion." Sir Joseph supposed that one chief cause of the intrusion
of English plants in Australia, and not vice versa, was the great
importation of European seed to Australia and the scanty return of
Australian seed.)

I have now looked and found passage in F.