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Darwin Correspondence Project

From J. D. Hooker   7 October 1878

Royal Gardens Kew

Oct 7/78

Dear Darwin

I had already read B. White’s paper, & corresponded with him about his conclusions. Unfortunately the Botany is all dead against him— There is no relationship whatever between the N. Atlantic Island Flora & that of St. Helena—1

You have marked a passage to the effect that “one or two genera of plants common to St H. & S. Africa are strongly suggestive of a Palæarctic origin, & dispersion by the influence of a glacial epoch in for example Sium, which has an endemic-representative in St Helena & the very characteristic Cape genus Pelargonium, which has a straggler in Syria”.2

Now the Sium, which I first described, I have stated to be clearly allied to the S. Thunbergii of the Cape, which is no Palæarctic form; & how Pelargonium is to be classed as Palæarctic, because one species grows in Syria, whilst hundreds are confined to the Cape, which is its headquarters, passes my comprehension.3 I have come to the conclusion that the Flora of St. Helena is very S. African & not in the least North Atlantic; & as the plants must have got to St. Helena before the Insects, these must, if they came from the North, indicate that the Flora has survived the glacial epoch i.e. had come from the Cape before it.—

The difficulty of attributing to the Flora a Miocene age or origin is, the absence of any old types, such as Conifers & Cycads or examples of exceedingly limited (ie. dying out) Nat. Ords.4 If I remember aright most or all the plants belong to large & very cosmopolitan orders, well represented in S. Africa. Ascension does not help; it’s only shrubs are of South African affinity & St. Helena & these are if I remember aright its only flowering plants (except tropical weeds.) St. Helena has affinities with Tristan d’Acunha—5 If we could only make the insects antedate the plants I would understand the arguments

Is the Entomology of the S. African mountains known? especially of those Mts of the W. Coast.

What Frank will do is just what I want— De La Rue has promised me a note on the subject of Spottiswoode’s researches on Electric currents.6

Ever aff yrs | Jos. D. Hooker.

I am working hard at the Rocky Mt Flora, & find that it contains many old world genera & species not found in the equally lofty Sierra Nevada, which runs parallel to it for so many hundred miles.—& I am excessively interested about it.7 One would suppose that the migration along the American meridional ridges from the north southwards & back again was the simplest thing in the world— but it has not been so I am sure.

The Rocky Mt Flora will stand a very fair comparison with the Altai,8 which the Sierra Nevada will not

Footnotes

CD had sent Hooker his offprint of a paper by Francis Buchanan White, ‘Contributions to a knowledge of the hemipterous fauna of St. Helena, and speculations on its origin’ (F. B. White 1878; see letter to J. D. Hooker, 5 October [1878]). St Helena is an island in the mid South Atlantic ocean, over 2000 miles east of the Brazilian coast and over 2000 miles north-west of the Cape of Good Hope.
The offprint sent to Hooker has not been found, but CD had transferred his marginalia from the offprint to the relevant issue of the Proceedings of the Zoological Society of London, to which he subscribed (see letter to J. D. Hooker, 5 October [1878] and n. 6). In the issue, now in the unbound journal collection in the Darwin Archive–CUL, CD scored a section of F. B. White 1878, p. 458, from ‘fauna is Palæarctic’ to ‘Syria’, and underlined ‘one or two genera of plants’. The term Palaearctic (referring to temperate parts of Europe and Asia) was coined by Philip Lutley Sclater, as one of his six zoological regions (Sclater 1857). Sium is a genus of water parsnips.
Hooker had described Sium helenianum in Hooker ed. 1867–91, 1: 23–4, as endemic to St Helena (the name is unresolved but is probably a synonym of Berula bracteata, jellico). Sium thunbergii is a synonym of Berula erecta (lesser water-parsnip), a species with a wide native distribution in much of the northern hemisphere, as well as East Africa from the Nile Delta south to South Africa. Pelargonium is a genus in the Geraniaceae (geranium) family with native distribution mainly in southern Africa, but with some species in Australia, the East African rift valley, and the Arabian Peninsula, as well as St Helena. The Syrian species P. endlicherianum was featured by William Jackson Hooker in Curtis’s Botanical Magazine 82 (1856): t. 4946.
The Miocene is a geological epoch, the earliest of the Neogene period. The family of cycads, formerly Cycadeae, is now known as the Cycadaceae. Conifers, formerly classed as Coniferae, are now in the class Pinopsida.
Ascension and Tristan da Cunha are islands in the South Atlantic Ocean. Ascension is 800 miles north-west of St Helena; Tristan da Cunha is over 1500 miles south.
See letter from J. D. Hooker, 4 October 1878 and n. 4. Francis Darwin was to provide Hooker with a list of his and CD’s published work (letter to J. D. Hooker, 5 October [1878]). Warren De la Rue and William Spottiswoode were researching phenomena associated with electrical discharge in a gas (see, for example, De la Rue and Müller 1878 and Spottiswoode and Moulton 1879).
Hooker was collaborating with Asa Gray on a study of the flora of the Rocky Mountain region in relation to other parts of the world; the work was published in 1880 (Hooker and Gray 1880). The Rocky Mountains extend from central New Mexico north-west to Alaska; the Sierra Nevada range is mostly in eastern California, extending into western Nevada.
The Altai is a mountain range in central Asia, largely in Russia and Kazakhstan, extending into Mongolia.

Bibliography

Sclater, Philip Lutley. 1857. On the general geographical distribution of the members of the class Aves. [Read 16 June 1857.] Journal of the Proceedings of the Linnean Society (Zoology) 2: 130–45.

White, Francis Buchanan. 1878. Contributions to a knowledge of the hemipterous fauna of St. Helena, and speculations on its origin. [Read 7 May 1878.] Proceedings of the Zoological Society of London (1878): 444–77.

Summary

Botanical evidence is against F. B. White’s origin of St Helena fauna. JDH holds flora is S. African. Since plants must arrive before insects, if fauna is Palearctic then flora survived glacial period. Flora not Miocene since old and relic orders are absent. Suggests S. African west coastal mountains as insects’ origin.

Letter details

Letter no.
DCP-LETT-11718
From
Joseph Dalton Hooker
To
Charles Robert Darwin
Sent from
Kew
Source of text
DAR 104: 118–20
Physical description
5pp

Please cite as

Darwin Correspondence Project, “Letter no. 11718,” accessed on 28 September 2021, https://www.darwinproject.ac.uk/letter/DCP-LETT-11718.xml

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