skip to content

Darwin Correspondence Project

From John Denny   16 August 1879

Stoke Newington,

August 16.th. 1879

Dear Sir

You may perhaps remember, we corresponded seven years ago, with reference to some varieties of the Pelargonium, which while similar to all appearance, (save being some what more robust) to the other varieties in my house, “proved to be sterile, excepting with each other.”1

I’ve since found that th⁠⟨⁠e⁠⟩⁠ two varieties are fertile with some varieties raised by Mons. Lemoine, but which varieties evidently arose either from self-fertilization, or crosses between these two, viz, Beautie de Surressnes & the Duke of Cornwall, or sports as was the case with the Doubles which were sports off Beautie de Surressnes, & all the varieties thus raised by Lemoine proved to be sterile—with the other varieties of the Zonal Pelargonium. I therefore consider them to constitute “a distinct Class”—or Species—as some would call them2

As you took much interest in my communication upon this subject at the time I refer to and—In reply to my Communication (Letter of July 15 1872) you remarked, that you considered I had made an important discovery as bearing upon the Origin of Species. As you could only account for the facts related by supposing that a variety—through cross breeding or some other cause—had arrived at a condition, which resulted in “a stop”, & refusal to be fertile with other varieties of its kind.3

You also asked me if I met with any thing in my cross breeding experience that further bore upon this point—or seemed of scientific interest—to communicate it to you

I must first tell you that I’ve continued to raise several thousand seedling Pelargoniums yearly, and as you may have seen by the horticultural press, have immensely improved the form & size of the flower but nothing has occurred of a scientific nature that I deemed worthy of troubling you with until now recently.4

You must bear in mind that the origin of the varieties Beautie de Surressnes & Duke of Cornwall were unknown to me. These being the varieties I quoted as infertile with the other varieties of Zonal pelargoniums—& these two varieties might have been raised from seed, or they might have resulted as sports.— I failed in any way to trace their origin

I now purpose describing a variety, & its origin which may tend to throw some light upon the probable origin of these varieties & possibly upon the origin of what are called species.

As I consider the matter of importance & interesting, I will go into details & endeavour to make myself intelligible

Upon a White Variety of my own raising, I one day observed at the top of one of its branches a very considerably larger flower than its fellow⁠⟨⁠s⁠⟩⁠ also that the leaves of this twig were larger & stouter.

I consequently made a cutting of & propagated this twig which grew into a plant of a much more robust habit than the the plant from which it was taken, & which also maintained its improvement in size & substance of blossom.— the cuttings taken from this plant have also increased in robustness of growth, until they resemble in form of foliage & habit precisely that of Beautie de Surressnes & the Duke of Cornwall. The flower also resembles in form & substance that of those varieties, save in colour—they being respectively pink, & scarlet.

But now I come to what seems to me the most important point—(viz) that this sport seems to be like the class refered to, equally sterile with other varieties—for I can neither get it to seed from the application of the pollen off the plant from which it was taken—or any other variety that I have as yet tried upon it, nor will its pollen fertilize.5

I do not now possess a plant of Beautie de Surressnes.—but I intend to obtain one, on purpose to try if they will prove fertile upon one another.

I have had no experience in sports of other plants—, but it would be interesting to know—if when they show considerable variation from the pla⁠⟨⁠nt⁠⟩⁠ from which they were tak⁠⟨⁠en⁠⟩⁠ whether they prove sterile with the pollen of its mother plant & similar varieties. Because should such be the case—it would undoubtedly indicate the origin of Species.

I shall continue my endeavours to cross this sport with my other varieties—. & I will try it with the pollen of Beautie de Surressnes,—also its pollen upon that variety, & should be happy to report to you with what result—if you consider the matter of interest to you

Dear Sir | Yours faithfully | John Denny

Chas. Darwin Esqre

Footnotes

See Correspondence vol. 20, letter to John Denny, 22 July 1872. CD had referred to Denny’s observations of Pelargonium zonale in Cross and self fertilisation, p. 142.
Victor Lemoine raised several varieties of pelargonium, including, in 1865, the first genuine double-flowered zonal pelargonium Gloire de Nancy, developed from Beauté de Suresnes (Dauthenay 1897, pp. 112–13). Zonal pelargoniums are so called because their leaves are divided into two colour zones.
No letter from CD to Denny on the significance of Denny’s experiments for the origin of species has been found. However, in a draft of a letter to Denny of 14 July [1872] (Correspondence vol. 20), which CD might have added to before sending it on 15 July, he had written that Denny’s discovery that the ‘Duke of Cornwall’ variety was fertile with its own pollen and some other varieties but sterile with others was remarkable. For Denny’s results, see Denny 1872a and 1872b. In Denny 1872b, p. 53, after remarking on the small number of good and novel varieties produced from a given number of seedlings, Denny quoted Origin, p. 486: ‘A new variety raised by man will be a far more important and interesting subject for study than one more species added to the infinitude of already recorded species.’
Denny’s varieties of pelargonium were reported on and advertised extensively in Gardeners’ Chronicle; see, for example, Gardeners’ Chronicle, 12 July 1879, p. 57.
The case was described in the report of the scientific committee of the Royal Horticultural Society in Gardeners’ Chronicle, 22 November 1879, p. 663.

Bibliography

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

Dauthenay, Henri. 1897. Les Geraniums: (Pelargonium zonale et inquinans); description et culture. Paris: Octave Doin.

Denny, John. 1872a. The relative influence of parentage in flowering plants. Gardeners’ Chronicle, 29 June 1872, p. 872, 6 July 1872, pp. 904–5.

Denny, John. 1872b. On cross-breeding pelargoniums. Florist and Pomologist (January 1872): 10–12, (February 1872): 34–6, (March 1872): 50–3.

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

JD communicates, after seven years, news of a new "sport" of Pelargonium, sterile both with other varieties and with the mother plant, thus indicating that it is possibly a new species.

Letter details

Letter no.
DCP-LETT-12195
From
John Denny
To
Charles Robert Darwin
Sent from
Stoke Newington
Source of text
DAR 162: 161
Physical description
ALS 10pp damaged

Please cite as

Darwin Correspondence Project, “Letter no. 12195,” accessed on 28 March 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-12195.xml

letter