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Darwin Correspondence Project

To Charles William Crocker1   18 May [1861]2

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

May 18th

My dear Sir

I am extremely much obliged to you for so kindly writing to me & offering me information.3 I have long been curious about Hollyhocks.—4 The Dean of Manchester told me that some kinds came true, even when growing near others.5 This surprised me greatly, as it can be shown to be almost certain that every flower must be fertilised by the pollen of a distinct flower. Hence I bought some good seed, & several kinds came up very true; the black-coloured kind came up absolutely true, & I saved its seed, & though a dozen different varieties were growing close, again all the seedlings were true. It can hardly be, judging from my extremely limited experience, that the flower always inherits its mother’s colour, for I castrated & crossed a dark purple with pollen of yellow kind, & there was great variability in the seedlings, but one seedling alone showed plainly the yellow colour of its father. In case of most plants pollen of another variety seems to have a prepotent effect over a plant’s own pollen, (as experiments made by myself have convinced me); & it has occurred to me whether in some very fixed vars. of Hollyhocks exactly the reverse was the case,—that is whether the pollen of a plant’s own variety was not prepotent over that of other varieties.

The facts which I wish to know, are whether some or many of the variations of Hollyhock come true by seed. And secondly whether the great raisers of Hollyhock seed, who sell named kinds, whether they grow the varieties far apart to prevent crossing.6 And thirdly, whether when vars. of Hollyhocks are artificially crossed & castrated, whether the colours of the seedlings are generally intermediate. I should be extremely much obliged for any information on these points or on the progress of your work of selection.—

I have not much time for reading, & have not yet seen your work, but must see it & your account of the vars. of Cassia.—7

I yesterday sent off another letter to Cot. Gardener:8 but I begin greatly to doubt the great Mr. Beaton.— He makes, I am sure, plenty of mistakes in his late discussions, & is dogmatic in highest degree

My dear Sir, your sincerely obliged | Charles Darwin9


The correspondent is identified by the relationship of the letter to the letter to C. W. Crocker, 1 June [1861].
Dated by the reference to CD’s letter to the Journal of Horticulture (see letter to Journal of Horticulture, [17 May 1861]).
Crocker apparently wrote to CD in response to the letter to the Journal of Horticulture, [before 14 May 1861]. Crocker’s letter has not been found.
CD had experimented with crossing hollyhocks: details of his experiments are recorded in his Experimental book (DAR 157a). See also Correspondence vol. 5, letters to J. S. Henslow, 10 November [1855] and 12 November 1855.
The noted hybridiser William Herbert was the dean of Manchester. See letter to Journal of Horticulture, [before 14 May 1861].
CD did obtain information on this point, stating in Variation 2: 107: ‘I have been informed that nurserymen who raise seed for sale do not separate their plants’.
The work has not been identified.
Letter to Journal of Horticulture, [17 May 1861]. CD questioned statements made in earlier articles by Donald Beaton.
The last two lines of the letter are in the hand of another writer, apparently owing to someone having excised CD’s signature.


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

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


Describes results of his experiments with hollyhocks. Some varieties breed true even though growing near others. This suggests that their pollen is "pre-potent" over that of other varieties, which is not the case with most plants. Asks some questions on which he would be glad to have correspondent work. [See also 3170.]

Letter details

Letter no.
Charles Robert Darwin
Charles William Crocker
Sent from
Source of text
Cleveland Health Sciences Library (Robert M. Stecher collection)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 3151,” accessed on 27 January 2021,

Also published in The Correspondence of Charles Darwin, vol. 9