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Letter 964

Hooker, J. D. to Darwin, C. R.

[25 Mar 1846]
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    Summary Add

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    JDH recognises the existence of "altered states" of continental species in island floras. The botanists' difficulty in determining a new species is no grounds for dismissing the important question of altered forms.

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    Will look for Ascension plants for Ehrenberg.

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    French Galapagos collections confirm JDH's view that plants arrived from north.

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    Cannot agree with Forbes on North Atlantic flora.

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    Botanical definition of "highness" and "lowness" usually means complexity and simplicity.

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    Some plants, such as aquatic ones, are cleistogamous. Cannot see why they should not be.

Transcription

West Park Kew

Wednesday Night.

My dear Darwin

Thanks to the Railways a few hours has sufficed to transport me to the heart of Norfolk whither I went for my sisters marriage, & back again. As soon as I possibly can, I hope tomorrow, I will look & see if I have any-thing worth Ehrenberg's having, from Ascension, in the shape of a Grass, including sedge I suppose, though as I did not collect with any idea of having the specimens made such a philosophical use of, my hopes are not high of proving useful.

I owe you for a famous letter & long to be at you with an answer, but shall refrain in full till I look over St Hilaire, whose notions on affaiblissement are not very familiar to me, & my own very crude.

When at Mr Bentham's I went through the French Galapago things & find more proof of the imported i.e. non peculiar plants being of a northern origin, in one of them being a decidedly Californian Baccharis (Compositæ) which was not in your Herb.. another is a new species of a California genus of Compos. (Hemizonia). These being done I am again ready to do a little to my notion of the distrib. of Gal. plants, though alas with hands fuller than ever. I think we are agreed on Polymorphism in the sense we did argue it, & also in that we are now about to treat it under. One of the great objects I had in view in my notice above alluded to, was to group the plants according to their derivation & I have a class in reserve for “apparently peculiar species possibly the altered forms of introduced plants” It is quite true that in most Islands there is a lot of very dubious species, by no means to be confounded with their country-men, & not polymorphous in the said Island, but woefully near certain continental congeners.

Thus I would divide the Galapago plants into 4 groups 1. Ubiquitous E.G. Avicennia— 2. of nearest continent as Baccharis. 3d Possibly altered state of continental species, as 4. original creations as Pleuropetalum or Scalesia. The 3d group may not be a large one in the Galapagos, (according to my notions) but its acknowledged existence is a matter of some importance. In the cases of Madeira, the Canaries & Azores, said group 3d must be very considerable. Such however is the difference of opinion amongst Botanists as to what should or not be a species, that the question in any shape will be a troublesome one, though not on that account to be dismissed unconsidered.

I stumbled on a splendid fact the other day, that the Lycopodium cernuum is only found in the immediate neighbourhood of the hot springs in the Azores. When alluding to its distribution at p. 114 of my Flora I dared not mention that it was not known to be an inhabitant of Madeira or the Canaries, as I thought it must turn up there, now however I do not expect it & feel sure that the presence of this torrid plant in the Azores is due to the hot-springs. What I am most pleased at is the apparent proof of the universal suspension of the sporules of this genus in the air & the consequent strengthening of my hypothesis, that the genus should be decimated sparing only every tenth!. Of course it is a strong fact for migration, & for the existence of the impalpable spawn of Fungi &c in all air.

I have been more coolly analyzing the bearings of Forbes Botanical question lately, & with the distressing result, that I fear I must haul out of all participation with him. You will think me unstable as water, & I must blame myself for speaking too much without thinking. It is not from a reconsideration of his facts & arguments that my faith is weakened, but from an independent examination of the Flora of the N. Atlantic Isles & W. U. Kingdom which shews, that there are plants in these regions which have been more put to in getting there than the Asturias ones' need have been. Such are the American plants Eriocaulon 7 angulare in the Hebrides & W. Ireland, An American Neottia in S. Ireland & Trichomanes brevisetum, in W. Ireland & Madira, all of them American plants not found further E. on continent of Europe or Africa. Also the Gymnogramma Totta a fern of the Cape only in Madeira & Azores & Myrsine Africana, which positively skips from the Cape across all intermediate Africa on one side to Abyssinia, & on the other to the Azores!. I hope to be allowed a conversation with Forbes on the subject, for really, with his Sargassum weed &c he is going too far.

Cannot Smith (Jordan Hill) give any information about the Miocene strata of Malta?—

Certainly there is no objection to the hypothesis of a Sargassum being an absolute creation, though I see no reason to call for such an aid in this case, the species being in my opinion decidedly the littoral Atlantic one

I was too rash in expressing as I did to you the W. African & Java Floras, as belonging to one & the same region. It is true enough they are disgustingly alike, without being absolutely the same. What I should have said was, that there was no marked Botanical features to seperate them, such as there are to seperate the Cape or Australia from either or one another. From Java to Benin through India the Flora is of the same type. The latter differs only in being rather more American than any country East of it, in wanting many fine Java things, & in poorly representing the most of the rest, whilst it hardly makes up for all these deficiencies by any peculiarity in genera or Nat. Ords. of its own. I think I am right in saying (though I would not print it) that the Benin Flora is more Javanese than the Peruvian is Brazilian. I must enter one caveat, that all we know of the Benin Flora is so much littoral that one's judgement can hardly help being warped.

Falconer is as you say a very nice fellow indeed, I do hope he will not be sent again to India with this work of his in hand, his knowledge of Palæontology is very great I believe,

I wonder I never thought of sending you Moq. Tandon, it is a very good systematic work on the subject, but will not answer all your ends.

I should be glad to hear your objections to St Hilairs theory, I do not at all subscribe to it, though the fact always appears to me astonishing, that you may cause a young leaf bud to become a flower bud by checking the progress of the sap in it. It is very easy to explain on what sort of grounds Botanists make one class of plants higher, & as easy to prove them futile by their results. I do not however think your objection valid urged on the grounds of Owens observations on organs which are developed in the animal kingdom, but which organs are valueless for systematic purposes if present even in the Vegetable. It is upon the modifications of the sexual organs & their accessories that all the Nat. Orders are defined. The organs of loco-motion afford the Botanist no characters, those of digestion next to none: & the mode after which the various component parts of a compound body (a plant) are arranged is valuable only for the 3 highest groups, Monocot. Dicot. & Acot. & not absolute even amongst these. Generally speaking in Botany highness & lowness are synonymous with complexity & simplicity of structure. I can hardly conceive either simplicity or complexity of one particular organ indicating the rank of a being in the scale of creation.

I believe that many plants shed their pollen in the bud & should have thought that impregnation might take place there too, I don't see why not. Many erect flowers have the stigma exserted long beyond the anthers. & I do not see why impregnation should not in some precede expansion as I think it does in some water plants. I shall keep it in mind. Moq. Tandon shall go to Athenæum with Hort. Soc. Journ. next week

Ever most truly Yours | Jos D Hooker

    Footnotes Add

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    f1 964.f1
    Dated from the relationship with letter to J. D. Hooker, [24 March 1846]. Maria Hooker married Rev. Walter McGilvray on 24 March 1846.
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    f2 964.f2
    Hooker left a space in the manuscript, presumably intending to insert a name later.
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    f3 964.f3
    James Smith, who had visited various Mediterranean locations during the winters of 1839–46.
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    f4 964.f4
    Moquin-Tandon 1841.
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    f5 964.f5
    Journal of the Horticultural Society of London, which included W. Herbert 1846.
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