skip to content

Darwin Correspondence Project

From Thomas Glover   26 October 1857

Smedley Hill Manchester

Oct 26. 1857—


Your letter of 22d. only came to hand this morning, or it should have been sooner replied to—1

Of course you know Cactus speciosissimus the beautiful shades of colour in the flowers perhaps surpass all others—but the habit of the plant is bad— I take this to be as true a species as any existing— There is another known by the name of stellatus, closely resembling Ackermanni, perhaps the same, the flowers of which are somewhat bricky in colour, but the habit of the plant is good— I dont know its origin but from the not distant resemblance the flowers bear to the one known as Jenkinsoni which is undoubtedly a hybrid, by speciosus on speciosissimus, having myself raised it in quantities, I suspect it may be a hybrid also.

Many years ago, it struck me that if a flower resembling speciosissimus could be produced upon a plant of the habit of stellatus, it would be a desirable acquisition & with the view of accomplishing this, I impregnated speciosissimus with stellatus, & stellatus with speciosissimus— I obtained, from each fruit, an abundance of perfectly fertile seeds— It never occurred to me to count the number, but my recollection serves me so far as to say confidently that the numbers which vegetated were about equal— they amounted in the whole to 3 to 400 & as soon as they could be well handled, were potted off in small pots 5 round the edge of each & carefully marked— The first plant bloomed in 1850 & produced a flower of much more lively colour than stellatus, & had also a tinge of blue in it. I impregnated this bloom with speciosissimus & obtained therefrom about 50 plants, only one of which has bloomed— it has a strong shade of blue in it, almost equal to speciosissimus, but the petals are not so even as speciosissimus— The plants that bloomed afterwards were poor in colour except one which was very promising, but it was stolen from me & though I offered a reward of £2. I could not recover it. In 1855 the last of the lot bloomed & amongst them were eight of very fine colour, the whole of which I impregnated with speciosissimus & the whole of which have come up as ‘thick as mustard’— this is as far as I have gone, but it is sufficient to prove that the hybrids are fertile— I also impregnated speciosissimus with one of the above flowers, & though the seed was to all appearance finer than any of the others fewer plants have come up— I may observe by the way that the difference in appearance of the two first named crosses is so small, that if they were not marked, I could not say which was which but in the second cross I think there are more stems that are angular [DIAGRAM HERE] —none are so prickly as speciosissimus—

I met with a plant in Guernsey last year but one, having the habit of my second cross & the bloom of a rose colour— I strongly suspect it to be a hybrid, as it came from a person whom I suspect, though entirely unknown to me, has been going on the same tack as myself. This I have also impregnated with speciosissimus & have a most abundant produce.

I have impregnated speciosissimus with flagelliformis & obtained plants almost identical with those known under the names of Palmerii, Mallinsoni &c all of which had bricky red blossoms.2 I also impregnated stellatus with flagelliformis, & obtained forms similar to Palmerii, but not so prickly but the blooms were rose colour— I never tried them any further but I don’t doubt their being fertile. These latter hybrids have all the form of flagelliformis—

There is or was a Mr Lukis & also a Dr Brock in Guernsey or Jersey who have d〈o〉ne a good deal in this way.

I have done nothing in Gloxinias beyond impregnating the common sorts one with another, & have obtained no results worth recording, but I have obtained a hybrid from Gloxinia tubiflora (quere, is this not nearer Gesneria?) impregnated with Gesneria Cooperi—the hybrid is barren. I sent them a plant to Kew—

I have also got hybrids from Franciscii confortiflora impregnated with latifolia but the plants are sickly & all variegated in the leaves.

I should have pleasure in sending you any of the above if you deemed them worth the Carriage

I am Yours faithfully | Thomas Glover.

CD annotations

‘Hybrid impregnated by Speciossissmus very fertile’added pencil
2.4 stellatus] underl pencil
2.4 Ackermanni] underl pencil
crossed pencil
scored pencil
Top of first page: ‘Hooker. Are C. spec. & Ackermanni very different forms’ pencil


See letter to J. D. Hooker, 30 September [1857], in which CD asked Joseph Dalton Hooker for Glover’s address to inquire about hybrid crosses of species of Cereus, a large genus of cactuses.
Hybrid crosses between Cereus speciosissimus and C. flagelliformis are mentioned in CD’s chapter on hybridism, but Glover is not cited as the authority (Natural selection, p. 412).


Natural selection: Charles Darwin’s Natural selection: being the second part of his big species book written from 1856 to 1858. Edited by R. C. Stauffer. Cambridge: Cambridge University Press. 1975.


Describes his work, which demonstrates that hybrids of Cactus are fertile.

Letter details

Letter no.
Thomas Glover
Charles Robert Darwin
Sent from
Source of text
DAR 165: 58
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 2160,” accessed on 30 November 2020,

Also published in The Correspondence of Charles Darwin, vol. 6