Writes on various observations and discoveries on dimorphic and trimorphic plants.
Octbr. 31. 1868.
My dear Sir
I am very sorry to learn from your letter of
The dimorphic plant, of which I enclosed dried flowers in
my letter of June 17
The family of Rubiaceæ continues to furnish me with dimorphic species; to the genera formerly mentioned (Borreria, Suteria, Hedyotis, Lipostoma, Manettia, Coccocypselum) I can now add Psychotria (3 or 4 species) and Faramea (These two genera have been named for me in Kew). There are now flowering in my forest many bushes of a very beautiful <Faramea> which is one of the most interesting dimorphic pla<nts I ever> saw.— The difference in the length of the styli an<d stamens of> the two forms is very considerable; in the long-styled form the antheræ are nearly sessile.
<pressed plant specimens and excised diagrams>
The two rami of the stigma are long and slender in the
short-styled,—short and much broader with the papillæ
more crowded together in the long-styled form. The
pollen-grains of the long-styled plants are about
In one of your letters you told me that all known species of Oxalis were trimorphic or monomorphic; now I have hardly any doubt, that one of our species is dimorphic. It is a small creeping plant with bright yellow flowers. I have gathered numerous specimens at several widely distant places, without finding a single short-styled plant. <diagram excised>The length of the styli in the long-styled and mid styled forms is rather variable, they are often scarcely longer or shorter than the longer stamens; there are even plants, in which the styli reach exactly to the level of the longer stamens. It may be worth mentioning, that this dimorphic plant closely resembles a monomorphic species, in which the styli equal in length the longer stamens and which fertilized <itself as> I found by experiment, without insect-aid.—
< > raised seedlings < > < >ine white tri-<morphic> Oxalis, which offer a curious instance of embryonic ressemblance. The leaves of the seedlings have the form typical in that genus, from which form the leaves of the adult plant deviate considerably.
There is another difference, not visible in the dried leaves; those of the seedlings are reddish beneath, those of the adult plant are green on both sides.—
As far as I can judge from wild plants, our several trimorphic Oxalis are quite sterile with own-form pollen or at least with the plant's own pollen. Two of our species propagate asexually with so extraordinary rapidity, that the descendants of the same mother-plant spread over large areas. I have seen in a large field (many acres) of young sugar-cane, the whole ground covered with the red blossoms of one of these species and all the flowers were of the same form.— Thus also all the white Oxalis growing on my own land are long-styled. Of these two species I have not yet seen a single pod on wild plants.— In my garden, where I have planted close together the three forms, the white Oxalis is now seeding freely.— Of two other trimorphic species (belonging to the section Thamnoxys Endl.) the three forms are commonly found mingled with each other and in this case they seed well, while isolated plants appear always to be sterile.—
After reading your paper on the illegitimate offspring of dimorphic and trimorphic plants, it occurred to me, that our sterile Oxalis, of which I formerly told you, might be an illegitimate plant, which had beaten in the struggle for life and exterminated its legitimate parents in consequence of a more luxuriant asexual reproduction; for according to Gærtner (Bastarderzeugung pg. 546) ``eine der ausgezeichnetsten und allgemeinsten Eigenschaften der Pflanzen bastarde ist die Luxuriation in allen ihren Theilen'', and it seems not to be improbable that some illegitimate plants should also possess this luxuriating growth of hybrids.— On this view the more or less complete contabescence of the anthers, the variability of the length of the styli in some plants and their equalling in length the shorter stamens in one of the two forms, as well as the doubleness of the flowers, which I have repeatedly observed, would be explicable.—
As to our Pontederia, I have made lately an excursion to the Itajahy-mirim, where it grows abundantly, in order to see whether it was indeed trimorphic; but unfortunately it did not yet flower.
The Eschscholtziæ, raised from your seeds, are now beginning to flower, so that in my next letter I hope to be able to give you the result of the experiments, which I am about to try.
With profound respect, believe me, dear Sir | very faithfully yours | Fritz Müller
- f1 6439.f1See letter to Fritz Müller, 17 August 1868.
- f2 6439.f2Fritz Müller's letter of 17 June 1868 is incomplete; the section where he refers to the dimorphic plant is missing. Aegiphila is spiritweed.
- f3 6439.f3Müller refers to the Itajahy (now Itajaí Açu) river.
- f4 6439.f4Müller had discussed the genus Lipostoma (now Coccocypselum) in 1866 (see Correspondence vol. 14, letter from Fritz Müller, 1 December 1866 and n. 12). In 1867, Müller had sent specimens of Borreria (now Spermacoce), and discussed his observations of heterostyly in Suteria (now subsumed within Psychotria), Hedyotis, and Manettia (see Correspondence vol. 15, letters from Fritz Müller, 4 March 1867, 2 June 1867, and 17 July 1867).
- f5 6439.f5In Forms of flowers, p. 135, CD noted Müller's observation of heterostyly in Psychotria, and on pp. 129--31, CD discussed in detail Müller's later paper on the dimorphic Faramea described in this letter (F. Müller 1869). Müller began corresponding with Joseph Dalton Hooker, the director of the Royal Botanic Gardens, Kew, in 1867, after receiving a letter from Hooker offering to name plants that Müller sent to Kew (letter from Fritz Müller to J. D. Hooker, 7 October 1867, Royal Botanic Gardens, Kew, DC vol. 215, doc. 168; see also Möller ed. 1915--21, 2: 149, letter from Fritz Müller to Hermann Müller, 17 October 1868, for some of the plants identified by Hooker).
- f6 6439.f6For a photograph of the plant specimens, see plate facing p. 822. The excised diagrams were probably of the two different forms of pollen grain (see Forms of Flowers p. 129).
- f7 6439.f7See Correspondence vol. 14, letter to Fritz Müller, [late December 1866 and] 1 January 1867; see also ibid., letter from Fritz Müller, 1 and 3 October 1866 and nn. 2 and 6.
- f8 6439.f8Müller probably refers to Oxalis corniculata (creeping wood sorrel); for more on the evolution of distyly in South American species of Oxalis, see Weller 1992, pp. 253--63.
- f9 6439.f9Müller refers to Oxalis regnellii, which has triangular leaves. Müller later published the results of some of his experiments with this species, without naming it (see F. Müller 1871, p. 75), but CD referred to the species by name when discussing Müller's experiments in Forms of flowers, p. 212.
- f10 6439.f10Thamnoxys is one of twelve divisions of the genus Oxalis given in Endlicher 1836--42, p. 1172.
- f11 6439.f11Müller had mentioned the sterile Oxalis in his letter of 1 and 3 October 1866 (Correspondence vol. 14). In `Illegitimate offspring of dimorphic and trimorphic plants', p. 431, CD had noted that some illegitimate offspring were `profuse flowerers'.
- f12 6439.f12The quotation is from Gärtner 1849, p. 526: `One of the most superb and most common characteristics of hybrid plants is the luxurious growth in all their parts'.
- f13 6439.f13Mirim: `little' in the Tupi language of Brazil (see William A. Reid, `Review', Language 20 (1944): 263).
- f14 6439.f14See letter to Fritz Müller, 3 April  and n. 5.
- f15 6439.f15CD had sent Müller seeds of Eschscholzia californica (California poppy) for experiments on self-sterility (see letter to Fritz Müller, 3 April  and nn. 1 and 2).