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Darwin Correspondence Project

From Fritz Müller   2 February 1867


Febr. 2. 1867.

My dear Sir

I am much obliged to you for your kind letter (without date)1 in which you ask about the number of capsules produced by the Maxillaria with the larger pods.2 I am told by a french collector M. Gautier that it is the Maxillaria tetragona; however his names are not always to be relied upon.—3 On large plants growing on rocks and covering often more than a square-foot you may sometimes find half a dozen or more, whilst smaller plants growing on trees yield rarely more than one or two. I think that hardly 20% of the flowers produce seed-capsules.4 The species is interesting in some other respects also. The bifid pedicelli of the pollinia execute the same movement, you have described in Maxillaria ornithorhyncha, the right and left pollen masses are connected by an elastic tissue like that of the caudicle.5

Whereas in all other Vandeae, I examined (Notylia, Cirrhaea, Ornithocephalus, Polystachya, Aëranthus, Oncidium, Cyrtopodium and several other species of Maxillaria), the margins of the valves of the seed-capsules are beset with hygroscopic hairs, I could not find them in the ripe pods of this species; but there are some scattered and rudimentary hairs in the young capsules.6

I send you pollen-tubes taken out of a young pod of this Maxillaria showing the fringes which from the six longitudinal ribbons extend between the ovula. On comparing these pollen-tubes with those of Cattleya Leopoldi7 you will be struck by a remarkable difference.

In Maxillaria (and with a single exception in all our Vandeae) the pollen-tubes remain fresh in their whole length; in Cattleya (as well as in all our Epidendreae) the upper part of the pollen-tubes soon becomes dry and black; this evidently is a consequence of the stigmatic chamber being shut in Vandeae, whilst it remains open and the pollen exposed to air in Epidendreae.8

I already told you in my last letter, that in Notylia and in Oncidium flexuosum, pollen and stigma of the same plant act, as it were, as a poison on each other; this is also the case with the curious Oncidium unicorne and with another species which seems to be nearly related to Oncidium pubes.9

I have had numerous racemes of a second species of Cirrhaea (perhaps the C. dependens Rchb. f.) interesting by the extreme variability of the colours of its flowers. I could not fertilize this species with fresh pollinia whilst it might be done easily after they had dried half an hour or an hour.10 This probably will prevent the flowers being fertilized with the same plants pollen. The disk in this species is provided with a hook facilitating its being taken away.

There begins now to flower here a curious small Orchid, viz. Ornithocephalus.


The anther-bed has a small transverse ridge on the anterior margin; the pedicellus of the pollinium passing over this ridge forms an obtuse angle; as soon as the pollinium is removed by an elastic binding of the pedicellus, this obtuse angle is transformed into a very acute one and subsequently by an hygroscopic movement, the pedicellus is curved in a very singular and elegant manner. In water the pedicellus returns to the former form.11 The two pods of Monachanthus which I fertilized (Dec. 25) with pollen of Catasetum mentosum are now already 7 cm long and as much in circumference.12

The plant of Oncidium flex., on which I had fertilized some flowers simultaneously with pollen from a distinct plant of the species and with pollen of Epidendrum Zebra, having perished by an accident I have repeated the experiment on another plant; the result has been the same and I have satisfied myself that it is indeed the side of the Epidendrum-pollen which grows less and that of the Oncidium-pollen which grows more rapidly.13


I have made in the first weeks of January a pleasant excursion on the continent, up the river Cubatão to the German colony Theresopolis;14 and have brought home a fine collection of living Orchids, among which a large plant probably belonging to the Catasetidae15   You state in your Orchis-book that there are flourishing in your neighbourhood 13 species of Orchids; now on the Cubatão you may collect on the branches of a single old Cedrela-tree even a larger number of species: half a dozen Maxillariae, four or five small Pleurothallidae, a couple of Oncidia, the Leptotes bicolor etc. The beautiful Miltonia cereola was very abundant.—16 The most striking feature of the Orchid-flora of Theresopolis was the abundance and variety of Maxillariae and the entire absence (as far I have seen) of the Cattleyae, the Amphiglott Epidendra,17 the Brassavola, which are the dominant littoral forms. Epidendra in general seem to be much more rare than here, where I already know 13 species....


In his letter to CD of 1 and 3 October 1866 (Correspondence vol. 14), Müller had estimated that there were 1,756,440 seeds in one Maxillaria capsule. CD told him he wanted to publish this fact and asked how many capsules were produced (ibid., letter to Fritz Müller, [before 10 December 1866]).
Maxillaria tetragona, native to Santa Catarina state, is now usually known as Bifrenaria tetragona and less often as Cydoniorchis tetragona. An old synonym was Lycaste tetragona. Hippolyte Gautier has not been further identified; Müller also mentioned him in his letter of 2 November 1866 (Correspondence vol. 14).
In Variation 2: 379 n. 34, CD mentioned that the Maxillaria described by Müller sometimes produced six capsules; see also ‘Fertilization of orchids’, p. 158 (Collected papers 2: 155), and Orchids 2d ed., p. 278.
For CD’s description of the pollination mechanism in Maxillaria ornithorhyncha, see Orchids, p. 191. For definitions of CD’s terms for orchid structures, see Orchids, pp. 5–8.
Müller had earlier mentioned hairs on the capsules of some orchids (see letter from Fritz Müller, 1 January 1867 and n. 19).
Cattleya leopoldii.
CD did not mention the varying conditions of the pollen-tubes in Epidendreae and Vandeae in the second edition of Orchids.
See Correspondence vol. 14, letter from Fritz Müller, 1 December 1866, and this volume, letter from Fritz Müller, 1 January 1867, for Müller’s descriptions of the poisonous effect of same-plant pollen in Oncidium flexuosum and Notylia. CD reported Müller’s finding in Variation 2: 134–5. See also Cross and self fertilisation, pp. 330, 341. Müller published his observations on the effects of same-plant pollen in F. Müller 1868a.
For Müller’s earlier observation on an unnamed species of Cirrhaea, see the letter from Fritz Müller, 1 January 1867 and n. 17. CD mentioned Müller’s observation of the second species in Orchids 2d ed., p. 172. Müller’s published account of Cirrhaea is in F. Müller 1868b and was cited by CD in ‘Fertilization of orchids’ (Collected papers 2: 150).
‘Anther-bed’: that portion of the column under, or surrounding, the anther (Dressler 1981, p. 308 s.v. ‘clinandrium’). CD included Müller’s account of the movement of the Ornithocephalus pedicel (now stipe) in Orchids 2d ed., pp. 159–60. Figure 14 (ibid., p. 160) was taken from Müller’s enclosed sketch of this movement.
Müller lived in Destêrro (now Florianópolis) on Santa Catarina Island. Rio Cubatâo flows into the Atlantic off the south end of the island. Theresopolis, on the Rio Cubatâo, is now Queçaba (West 2003).
CD and Müller considered the Catasetidae a subfamily within the tribe Vandeae (Orchids 2d ed., p. 178); for a recent classification, see Dressler 1993, pp. 168–70.
See Orchids, p. 345. In Orchids 2d ed., p. 279, CD added that Müller found more than thirteen species of orchid on a single Cedrela tree.
Amphiglottis is a synonym (no longer accepted) for some species of Epidendrum.


Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

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

Dressler, Robert L. 1981. The orchids: natural history and classification. Cambridge, Mass., and London: Harvard University Press.

Dressler, Robert L. 1993. Phylogeny and classification of the orchid family. Cambridge: Cambridge University Press.

‘Fertilization of orchids’: Notes on the fertilization of orchids. By Charles Darwin. Annals and Magazine of Natural History 4th ser. 4 (1869): 141–59. [Collected papers 2: 138–56.]

Orchids 2d ed.: The various contrivances by which orchids are fertilised by insects. By Charles Darwin. 2d edition, revised. London: John Murray. 1877.

Orchids: On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing. By Charles Darwin. London: John Murray. 1862.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.

West, David A. 2003. Fritz Müller. A naturalist in Brazil. Blacksburg, Va.: Pocahontas Press.


Thanks for CD’s letter inquiring about capsules produced by the Maxillaria with larger pods [see 5331]. Gives descriptions of Maxillaria and of the other Vandeae.

Describes Oncidium flexuosum.

Tells of botanical results of recent excursion to the German colony Theresopolis. Brought home fine collection of living orchids.

Letter details

Letter no.
Johann Friedrich Theodor (Fritz) Müller
Charles Robert Darwin
Sent from
Desterro, Brazil
Source of text
Möller ed. 1915–21, 2: 109–11; DAR 70: 146
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5389A,” accessed on 13 June 2021,

Also published in The Correspondence of Charles Darwin, vol. 15