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Darwin Correspondence Project

To Friedrich Hildebrand   20 April [1866]

Down. | Bromley. | Kent. S.E.

April 20th

Dear Sir

I am very much obliged to you for so kindly sending me your most interesting papers.1 The cases of Lopezia & Schizanthus are quite new to me.2 A Botanical friend, Mr. Henslow, was staying here a fortnight since, & detected & showed to me the curious movements in Indigofera, which grew in my greenhouse.—3

You may perhaps like to hear that in 1860 I watched Bombus lapidarius sucking the flowers of Pedicularis sylvatica, & I saw all that you describe: when the Bee forced its head into the corolla, the slit in the upper helmet-like petal opened & the anthers & stigma were rubbed on its back, so that its back was white with pollen.—4

Several years ago I protected Medicago lupulina from insects, & its fertility was much impaired, but not wholly prevented.5 I know of many cases in which in the same genus one species requires insect aid & another is sufficiently or fully fertile without such aid; but in this latter case the flowers are nevertheless repeatedly crossed by adjoining plants.

I have not yet read your paper on Salvia, but I recognize the beautiful structures in your excellent drawings with which I am familiar.—6

I hope that you will continue your interesting researches, & with sincere respect, | remain Dear Sir | Yours truly obliged | Ch. Darwin


CD had received copies of Hildebrand 1866a and 1866b. See letter to George Henslow, 16 April [1866] and nn. 2 and 5.
For Hildebrand’s descriptions of Lopezia coronata and Schizanthus pinnatus, see Hildebrand 1866a, pp. 75–7.
George Henslow had visited CD from 2 to 3 or 4 April 1866 (Emma Darwin’s diary (DAR 242)). He had been preparing a paper on pollination mechanisms in Indigofera (see letter to George Henslow, 16 April [1866] and n. 2).
Pedicularis sylvatica, commonly known as lousewort, is described in Hildebrand 1866a, pp. 10–11. CD reported his observations of bees visiting P. sylvatica in Cross and self fertilisation, p. 422.
CD had written a note on Medicago lupulina that was included in a paper by Henslow on cross-pollination by insects in Medicago sativa (Henslow 1865). See Correspondence vol. 13, letter to George Henslow, [2–5 November 1865]. CD’s observations were also published in Cross and self fertilisation, p. 368. His notes on M. lupulina, dated 1859, are in DAR 157a: 45.
CD refers to Hildebrand 1866b. See letter to George Henslow, 16 April [1866] and n. 5.


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

Cross and self fertilisation: The effects of cross and self fertilisation in the vegetable kingdom. By Charles Darwin. London: John Murray. 1876.

Henslow, George. 1865. Note on the structure of Medicago sativa, as apparently affording facilities for the intercrossing of distinct flowers. [Read 16 November 1865.] Journal of the Linnean Society (Botany) 9 (1867): 327–9.


Is obliged to receive FH’s papers. The cases of Lopezia and Schizanthus are new to him.

In 1860 CD watched Bombus lapidarius sucking the flowers of Pedicularis sylvestris and saw what FH has described.

Has not yet read the paper on Salvia.

Letter details

Letter no.
Charles Robert Darwin
Friedrich Hermann Gustav (Friedrich) Hildebrand
Sent from
AP 20 66
Source of text
Morristown National Historical Park (Lloyd W. Smith MS 698)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5062A,” accessed on 7 December 2021,

Also published in The Correspondence of Charles Darwin, vol. 14