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Darwin Correspondence Project

From T. F. Cheeseman   27 June 1873

Auckland, New Zealand,

June 27th. 1873.

Dear Sir.

The well known interest which you take in the fertilisation of Orchids, has induced me to forward you the enclosed copy of a paper contributed by me to the New Zealand Institute; in which I have attempted to describe the singular contrivances in our species of Pterostylis.1 I thought, too, that the regret you express, in your book on the subject, at not being able to examine any species with an irritable labellum,2 might be advanced as an additional excuse for the liberty I have taken in sending you an account of a mode of fertilisation depending entirely on this irritability.

My observations, and the experiments I have made, seem to me to fully warrant the conclusions I have arrived at in my paper. I should much like, however, if it would not be trespassing too much on your good nature, to have your opinion on the subject.3 Do you not think that the Australian Genus Calæna, in which the labellum is even more irritable than in Pterostylis, is likely to be fertilised in an analogous manner? I have not seen recent specimens, but the plant is so nearly allied to Pterostylis that this view seems highly probable

If it would be of any use to you I should be happy to forward you specimens of our Orchidea or to procure you any information in my power.

I remain | Yours very faithfully | Thos. F. Cheeseman

Charles Darwin Esq F.R.S....


Cheeseman’s paper, ‘On the fertilisation of the New Zealand species of Pterostylis’, was published in the Transactions and Proceedings of the New Zealand Institute (Cheeseman 1872).
See Orchids, p. 172.
Cheeseman observed that the labellum of Pterostylis trullifolia closed when an insect entered the flower, leaving only a small opening through which the insect might escape after it brushed first against the viscid surface of the rostellum, and then against the pollinia; cross-pollination was then effected when the insect visited the next flower (Cheeseman 1872, p. 354). CD added Cheeseman’s description of P. trullifolia to Orchids 2d ed., pp. 86–8.


Sends his paper on fertilisation of the New Zealand species of the orchid Pterostylis [Trans. & Proc. New Zealand Inst. 4 (1871): 270–84].

Letter details

Letter no.
Thomas Frederick Cheeseman
Charles Robert Darwin
Sent from
Source of text
DAR 161: 137
Physical description
3pp & ACCS 3pp

Please cite as

Darwin Correspondence Project, “Letter no. 8955,” accessed on 16 December 2017,

Also published in The Correspondence of Charles Darwin, vol. 21