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Darwin Correspondence Project

From J. D. Hooker   [9 March 1859]1

Kew

Wednesday.

My dear Darwin

I enclose your sentence slightly modified. I suppose you refer to Phænogamic plants chiefly—2 The greatest division are the two into Vegetables fecundating by pollen tube on ovule contents, in (Phænogams) &—the promiscuous always direct contact of naked cells in Cryptogams.

The Cryptogams are classified very much by vegetative organs, as well as by reproduct. The Phaenogams primarily divide into Monocot & Dicot which appear absolutely distinct.

1 Monocot.

a.Vasc. tissue of promiscuous bundles, in single system

b.Cotyledones of one folded leaf, or if more then alternate

c Germination—primordial leaves alternate—

Root sheathed in radicle.

2 Dicot—

a Vasc. tissue of seriated bundles in double system

b.Cotyledon two & opposite or more in whorls or opposite pairs.

c Germination—primordial leaves opposite.

Radicle lengthens & forms a branching descending axis.

Of Monocot. there are no sub-divisions depending on Embryologic characters of any great moment. Most are albuminous: very few Prealb.

Dicots. branch into Angiosperms & Gymnosperms, depending primarily on reproductive process

1.Angiosperms have the coverings of reproductive organs most highly specialized, the organs & processes simple & as in Monocots.

2 Gymnosperms have coverings of reproductive organs simple & incomplete; the organs & processes themselves infinitely more complex & specialized structurally & physiologically than Angiosperm or Monocot.

If you take reproductive organs as test of highness or lowness then Coniferæ are top of V.K.— if you take coverings of these & neglect the organs themselves, you may place them below Monocots.—but in so doing you neglect the vascular system germination & Embryolog. characters which are all as in Dicots, not as in Monocots3

As to my blessed Essay—it will stand weeks in type, so there will be no manner of hurry in reading & returning proofs.! I am sending it to press—now4

Ever yrs | J D Hooker

CD annotations

Top of first page: ‘Classification of Plants in relation to Embyology’ pencil; ‘12’5 brown crayon, circled brown crayon

Footnotes

The Wednesday before CD’s reply, in which he stated he had just received Hooker’s ‘note on embryology’. See letter to J. D. Hooker, 11 March [1859].
See letter to J. D. Hooker, 2 March [1859]. The sentences that CD wished to add to his discussion on the relations of embryology to classification (Origin, pp. 418–19) read: Yet it has been strongly urged by those great naturalists, Milne Edwards and Agassiz, that embryonic characters are the most important of any in the classification of animals; and this doctrine has very generally been admitted as true. The same fact holds good with flowering plants, of which the two main divisions have been founded on characters derived from the embryo,—on the number and position of the embryonic leaves or cotyledons, and on the mode of development of the plumule and radicle.
Hooker was one of the few botanists who believed that the Coniferae were highly developed plants in taxonomic terms. See Correspondence vol. 6, letter from J. D. Hooker, 22 November 1856.
Hooker 1859.
CD’s notes on classification were kept in portfolios eleven and twelve.

Bibliography

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.

Summary

Outlines the basic categories of phanerogams.

Places Gymnospermae in the dicotyledons.

Evaluates the variable utility of embryological characters in plant classification.

Letter details

Letter no.
DCP-LETT-2428
From
Joseph Dalton Hooker
To
Charles Robert Darwin
Sent from
Kew
Source of text
DAR 100: 152–3
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 2428,” accessed on 21 February 2020, https://www.darwinproject.ac.uk/letter/DCP-LETT-2428.xml

Also published in The Correspondence of Charles Darwin, vol. 7

letter