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Darwin Correspondence Project

From E. J. Johnston   24 May 1875

14 Wycliffe Grove, | Lavender Hill, | Wandsworth Road | S.W.

24 May 1875.

Dear Sir,

On Friday (21st) I sent you some living plants of the Araujia sericofera, which I hope have reached you in good condition. I have now the pleasure of enclosing a packet of seeds of the same, received in a letter from my friend in Oporto.1 The plant being common there, the gardeners do not keep the seed; which was the only cause of the delay in obtaining it.

I observe that recent writers refer the Araujia of Brotero to Physianthus. P. albens, (Bot. Reg. N.S. III. 1832, vol. 6.) closely resembles my plant in leaves, flowers, and general appearance. The description says:—“Stigma large, conical, angular, terminated above by two appendages longer than itself, which diverge below, meet near their apices, and again diverge”; which comes very near the stigma of Araujia. The plate of P. albens, however, represents these appendages as converging without meeting.2

In my letter of 16th March I spoke of the Araujia as belonging to the Apocyneæ. I ought to have said the Asclepiadaceæ. I was misled by the statement of Brotero, that the plant belonged “to the Apocyneæ of Jussieu,” and forgot that his Apocyneæ are not co-extensive with those of later writers.3 My error seems the greater on looking again at the sketch I made, for on it I find the natural order correctly noted.

There is another mistake (proceeding from imperfect recollection) which I wish to correct. I represented Knapp as having said that the Apocynum, in catching flies, acts by the stigma; whereas, according to him, it operates by means of the stamens. His language upon this point is perfectly clear: he says that when a fly alights on the flower, “the filaments close”, and detain it until it is dead; “the filaments then relax, and the body falls to the ground”. One of his figures represents “two expanded anthers ready for capture”, and another the “anthers closed” over the pistil, “and the prey captured”.4 My mistake arose, I think, in this way: I had a pretty distinct recollection of the two expanded anthers in his figure (the other three having been removed) though not of the pistil, and had completely forgotten all the portions of the description above quoted. Under these circumstances, recollecting the binary structure of the fruit, my memory had transformed the two stamens into two stigmas.

I have to ask your indulgence for these errors, as I wrote almost entirely from memory, and could not at the moment consult the books which I have since seen, and which I was then desirous of referring to. The “Journal of a Naturalist”5 I had certainly not seen for more than twelve years. I have lately seen several old and modern notices of the fly-destroying habits of the Apocynum; but the accounts of the modus operandi of capture seem to be very conflicting.6 I also enclose a small packet of seed of the Drosophyllum lusitanicum, Link, (Drosera lusitanica Linn) an insect-capturing, and in all probability, like its English allies, an insect-digesting plant. The seeds were sent by my botanical friend along with those which I undertook to procure for you; and he informs me that “it seems to prefer peat in quartzy alluvion, the sand being often like pebbles”. I hope this may be interesting to you in connection with your present researches.7

I remain, | Dear Sir, | Yours faithfully, | Edwin J. Johnston Jr.

CD annotations

4.2 Knapp] ‘in Journal of a Naturalist’ interl pencil

Footnotes

Johnston had promised to send CD seeds of Araujia sericifera in order that he might observe how flowers of this species caught insects (see letter from E. J. Johnston, 22 March 1875). Johnston’s friend in Portugal has not been identified. Araujia sericifera is the common moth-vine or cruel plant; ‘sericofera’ was an incorrect spelling that had appeared in Brotero 1815 (see n. 2, below).
Félix de Avellar Brotero had first described Araujia sericifera in Brotero 1815. The description and plate of Physianthus albens appeared in Edwards’s Botanical Register n.s. 8 (1836), fol. 1759. Physianthus albens is a synonym of Araujia sericifera.
See letter from E. J. Johnston, 16 March 1875 and n. 6. Brotero made this comment in Brotero 1815, p. 68. Antoine Laurent de Jussieu was the first to publish a natural classification of flowering plants; although many of his families are still used, changes were made to his system in the nineteenth century. John Lindley made asclepiads a separate group in the natural order Solanales, but noted a ‘lateral affinity’ between the Asclepiadaceae and the Apocynaceae (in his natural order Gentianales; see Lindley 1853, p. 615). Araujia is currently in the family Apocynaceae; Asclepiadaceae is now a subfamily, Asclepiadoideae, in the family Apocynaceae.
See letter from E. J. Johnston, 16 March 1875. John Leonard Knapp described the destructive powers of the North American Apocynum androsaemifolium (flytrap dogbane) in [Knapp] 1829, pp. 81–2, and figured its capture mechanism in plate I, fig. 5.
CD had first discussed Apocynum androsaemifolium and accounts of its fly-catching mechanism in 1860 (see Correspondence vol. 8, letter from Daniel Oliver, 23 November 1860, and letter to Asa Gray, 26 November [1860]). Johnston had speculated about possible mechanisms in his letter of 16 March 1875.
CD had already received living specimens of Drosophyllum lusitanicum (Portuguese sundew or dewy pine) from several correspondents (see, especially, Correspondence vol. 17); his experiments on it are described in Insectivorous plants, pp. 332–44.

Bibliography

Brotero, Félix de Avellar. 1815. Descriptions of a new genus of plants named Araujia, and of a new species of Passiflora. [Read 7 November 1815.] Transactions of the Linnean Society of London 12 (1817–18): 62–75.

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

Insectivorous plants. By Charles Darwin. London: John Murray. 1875.

[Knapp, John Leonard.] 1829. The journal of a naturalist. London: John Murray.

Lindley, John. 1853. The vegetable kingdom; or, the structure, classification, and uses of plants, illustrated upon the natural system. 3d edition with corrections and additional genera. London: Bradbury & Evans.

Summary

The insect-capturing Araujia has been forwarded from Portugal.

He discovers Apocynum is not in the same family, and he has misquoted [John Leonard Knapp’s Journal of a naturalist (1829)]; Apocynum captures by stamens, not stigma.

Sends seeds of Portuguese Drosera.

Letter details

Letter no.
DCP-LETT-9992
From
Edwin John Johnston
To
Charles Robert Darwin
Sent from
London, Wycliffe Grove, 14
Source of text
DAR 168: 76
Physical description
4pp

Please cite as

Darwin Correspondence Project, “Letter no. 9992,” accessed on 20 September 2021, https://www.darwinproject.ac.uk/letter/DCP-LETT-9992.xml

Also published in The Correspondence of Charles Darwin, vol. 23

letter