To W. T. Thiselton-Dyer 4 December 1873
Down, | Beckenham, Kent.
Dec 4 1873
My dear Mr Dyer
As Hooker is so busy I shd be very much obliged if you could give me the name of the enclosed poor specn. of Cassia. I want much to know its name, as its power of movement, when it goes to sleep, is very remarkable. Linneus I find, was aware of this.1
It twists each separate leaflet almost completely round, so that the lower surface faces the sky, at the same time depressing them all. The termals2 leaflets are pointed towards the base of the leaf. The whole leaf is also raised up about 12o.
When I saw that it possessed such complex powers of movement, I thought it wd utilize its power to protect the leaflets from rain. Accordingly I syringed the plant for 2 minutes, & it was really beautiful to see how each leaflet on the younger leaves twisted its short sub-petiole, so that the blade was immediately directed at an angle between 45o & 90o to the horizon.3 I cd not resist the pleasure of just telling you why I want to know the name of the Cassia. I shd add that it is a greenhouse plant— I suppose that there will not be any better flowers till next summer or autumn.
Forgive this trouble, & believe | me Yours very sincerely | Ch. Darwin
Footnotes
Bibliography
Linnaeus, Carolus (Carl von Linné). 1753. Species plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. 2 vols. Stockholm: Laurentius Salvius.
Linnaeus, Carolus (Carl von Linné). 1755. Somnus plantarum. Doctoral dissertation of Peter Petersson Bremer under the supervision of Linnaeus. Uppsala: n.p.
Movement in plants: The power of movement in plants. By Charles Darwin. Assisted by Francis Darwin. London: John Murray. 1880.
Summary
Wishes to identify a species of Cassia whose movements interest him.
Letter details
- Letter no.
- DCP-LETT-9171
- From
- Charles Robert Darwin
- To
- William Turner Thiselton-Dyer
- Sent from
- Down
- Source of text
- Royal Botanic Gardens, Kew (Thiselton-Dyer, W. T., Letters from Charles Darwin 1873–81: 1–2)
- Physical description
- LS(A) 3pp
Please cite as
Darwin Correspondence Project, “Letter no. 9171,” accessed on 26 September 2022, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-9171.xml
Also published in The Correspondence of Charles Darwin, vol. 21