From W. T. Thiselton-Dyer   28 September 1875

Royal Gardens Kew

Septr. 28. 75

Dear Mr Darwin

Before I heard from you I found in another number the illustration of the Citron-orange and here is a rough tracing of it.1

In the Gardeners’ Chronicle Septr. 25. p. 398 there is a remarkable account of some hybrid Aroids by Prof. Karl Koch of Berlin which exhibit in a modified degree the same curious phenomena of dissociation which are so wonderful in Cytisus Adami.2

When I was in Switzerland I collected a head of fruits of a species of Geum which externally are in no respect different to those of some species Anemone or Clematis. You might like to try if these will bury themselves (if they are not spoilt by pressure—but probably they would come all right after damping and then drying)   It is very curious finding fruits so similar in two so different natural orders.3

We have now at Kew a sensitive plant Schrankia aculeata which was new to me. The pinnæ drop when the pinnules close but the main rachis does not as in mimosa pudica4

diagram

I am afraid I trouble you with very trivial matters

Yours very truly | W. T. Thiselton Dyer

CD annotations

1.1 Before … natural orders. 3.5] crossed pencil
4.1 Schrankia aculeata] underl red crayon
4.1 Schrankia aculeata … mimosa pudica 4.3] double scored red crayon
4.1 new to me] underl red crayon
4.2 mimosa pudica 4.3] ‘(& Sea-shore Plants)’ added pencil
1
CD’s letter to Thiselton-Dyer has not been found.
2
Karl Heinrich Emil Koch commented in Gardeners’ Chronicle, 25 September 1875, pp. 398–9, that hybrid aroids resembled Cytisus adami in that one branch of a plant was often like the male parent, while another was like the female, and a third was intermediate. Aroids: members of the Araceae family, or arums. CD discussed the hybrid laburnum Cytisus adami (now known as +Laburnocytisus adamii) in Variation 1: 387–91. See also, for example, Correspondence vol. 13, letter to J. D. Hooker, [1 May 1865] and n. 3. Cytisus adami was a graft hybrid of the common yellow laburnum C. laburnum (now Laburnum anagyroides) and C. purpureus (a synonym of Chamaecytisus purpureus, purple broom). Cytisus adami was noted for its red, sterile flowers, but frequently some branches would revert to either parent form, bearing yellow or purple flowers.
3
Francis Darwin mentioned Anemone and Clematis in his paper on the hygroscopic properties of awned seed (F. Darwin 1876c). Geum belongs to the family Rosaceae, Anemone and Clematis belong to the family Ranunculaceae.
4
CD mentioned Schrankia aculeata in Movement in plants, pp. 381, 403. He discussed Mimosa pudica at greater length (e.g. ibid, pp. 37, 105, 375–9). Schrankia aculeata is a synonym of Mimosa quadrivalvis, sensitive briar .

Please cite as “DCP-LETT-10174,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-10174