RECORD: Bonavia, E. 1868. Peloric form of Clitoria ternatea. (Forwarded by Darwin) Gardeners' Chronicle and Agricultural Gazette (26 September): 1013.

REVISION HISTORY: Transcribed and edited by John van Wyhe. RN1

NOTE: See the record for this item in the Freeman Bibliographical Database by entering its Identifier here. Emanuel Bonavia was a Maltese medical officer and naturalist (1826-1908). In their notes to this letter to Darwin, the editors of the Correspondence write: "Clitoria ternatea, a tropical plant in the family Leguminosae, is known as the butterfly pea, blue pea, or blue vine (see Mabberley 1997). Leguminous flowers are normally bilaterally symmetrical; peloric forms are abnormal variants displaying radial symmetry. CD discussed other peloric plants, including his experiments on Antirrhinum (the snapdragon), in Variation 2: 58–60, 345–6. See also Correspondence vols. 11–14. Bonavia observed C. ternata in Lucknow, where he was the civil surgeon with the Bengal Medical Service (Oldenburg 1984, p. 97, Darmanin 1998). The drawings have not been found.
In leguminous flowers, the vexillum or standard is the largest, and usually the uppermost, petal, and encloses the others; the alae are the side petals; and the carina consists of the two lower and usually smallest petals (see A. Gray 1857a). The drawings were not reproduced in the Gardeners' Chronicle, where this excerpt from Bonavia's letter was published." Correspondence vol. 16, pp. 727-8.


[page] 1013

— WE are enabled, through the courtesy of Mr. DARWIN, to publish the following description of a PELORIC FORM OF CLITORIA TERNATEA observed at Lucknow by Dr. BONAVIA:"Regarding peloric forms of flowers, I have observed an instance which appears unrecorded in the Clitoria Ternatea. I send you herewith two imperfect coloured drawings, made by a native artist, to illustrate the striking difference between the irregular and peloric form. The Clitoria Ternatea is a scandent twining plant, with solitary flowers in the axils of the leaves. As you know, the vexillum, contrary to most pea-shaped flowers, is lowermost. No. 1 shows the irregular form. It presents the following characters:—Segment of calyx corresponding to the carina longest, vexillum large, emarginate, having in its middle part a yellowish white patch, with veins pinnately disposed, its margins meet round the alae and carina; alae small, with recurved blue margins adhering to the carina; carina white, completely enclosed by the alae; stamens ten, diadelphous. In the fully developed peloric flower of the Clitoria Ternatea the alae carinae, and vexillum are of equal size; they all have that middle yellowish white patch which, in the irregular form, is found only in the vexillum. Some flowers are so beautifully peloric that there is no distinguishing which petal represents the vexillum. I made a section with a knife through all the petals of one of these forms. This section shows well the twisted disposition of the petals, each of which is overlapped by the edge of the next petal. The stamens are ten, and all free and regularly disposed. This peloric form is transmitted by seed. Different forms of Clitoria graduate from the ordinary irregular shape up to the perfectly peloric flower. Different degrees of pelorism are found as a rule on different plants, but many degrees are often found on the same plant. I have observed six well marked degrees:—

"A. Natural. Alae small, edges recurved, and completely hiding the carina; one stamen free, nine united. This form I have always seen by itself on a plant. No peloric ones on same plant.

"B.  One of the alae larger than the other, more expanded, allowing the carina (which is a little larger than usual) to be visible; three stamens free, seven united.

"C.  Alae much developed, and only one of the petals of the carina largely developed; two stamens united, eight free.

"D. Alae almost as large as the vexillum, but still occupying the place of the alae; petals of carina both much developed, but still somewhat enclosed by the alae; all stamens free.

"E.  All the five petals are equal in size and similarly marked, but in aestivation the vexillum is still the outermost petal: the other four petals have a somewhat twisted disposition, totally different from that of alae and carinas; all stamens free. The plants which bear this form also bear some flowers, which are

"F. Perfectly peloric, and in which (all stamens free, and regularly disposed) neither vexillum, alae, or carinae are distinguishable. One edge of each petal is free, while the other is overlapped by the free edge of the petal next to it.

"I have seen several specimens with four petals only, of equal size, and with eight stamens. I have white varieties of this Glitoria, which are also peloric."

The peloria in question affords a good illustration of irregular peloria, or that form in which the flower is rendered symmetrical by the augmentation of the irregular segments. In other words, there are here five standard-petals instead of one, owing to the replacement of the wings and keel by petals of the standard form. It is interesting, also, as showing how Papilionaceae may merge into Rosaceae. As the form is not only interesting in a scientific point of view, but also very attractive in a florist's sense, we trust Dr. Bonavia will endeavour to perpetuate it, and by selection improve it.


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Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)

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