From Fritz Müller   18 December 1869

My dear Sir

I have to thank you for having kindly favoured me with a copy of your “Notes on the fertilization of Orchids” which contain a large number of interesting facts quite new to me.¹

A few days ago I returned from an excursion, on which I made a rich harvest of dimorphic and trimorphic plants. There were about half a dozen dimorphic Rubiaceæ, and among them the beautiful Rudgea eriantha. ²

[RUDGEA SPECIMEN]

But the most interesting plant was a Pontederia, which I had long ago suspected to be trimorphic and which now indeed I found to be so.³

⁠⟨⁠equivalent of 5 or 6 lines excised⁠⟩⁠

This is, I think, the first case of trimorphism or dimorphism among monocotyledons and in irregular flowers. The three longer stamens do not alternate with the shorter ones, nor belong to the same whorl; one of the longer stamens is inserted to the anterior sepal, two to the lateral petals; one of the shorter ones to the posterior petal, which is marked with a yellow spot, and two to the lateral sepals. (In the allied monomorphic genus Heteranthera, at least in H. reniformis, the three shorter stamens of Pontederia are wanting.)⁴ I was much surprised, that among hundreds of plants I could not find a single mid-styled one, and I have have hardly any doubt, that this form does not exist in the Itajahy-mirim,⁵ where this species grows abundantly.— The long-styled and short-styled plants could be distinguished even from a distance, the flowers of the former being paler, than those of the latter; in the dried flowers this difference has disappeared.— In a former letter I have sent you a mid-styled flower of a second species of Pontederia, which has been introduced here some years ago from Rio de Janeiro.—⁶

As to dimorphic Rubiaceæ, Professor Hildebrand told me, that Bernouilli (in Guatemala) had observed Coffea arabica to be dimorphic, producing hermaphrodite and small female flowers; but this is an error.⁷ The small flowers are rudimentary and sterile ones which occasionally appear among the normal flowers. I have lately seen these aborted flowers in unusual number on coffee-trees, which had been damaged by hail some weeks before.

Of the Begonia with monstrous male flowers I have raised four lots of seedlings and it is curious, in how odd a manner the monstrosity has been transmitted.⁸ The female flowers, from which the seeds were obtained, had all been fertilized with pollen of monstrous male flowers.

⁠⟨⁠    ⁠⟩⁠ seeds of a normal female flower. ⁠⟨⁠    ⁠⟩⁠ ⁠⟨⁠o⁠⟩⁠f which have normal and 2 monstrous ⁠⟨⁠    ⁠⟩⁠ of ⁠⟨⁠    ⁠⟩⁠ male ⁠⟨⁠    ⁠⟩⁠

3^d lot. Seeds of a female flower, which had 6 petals instead of 5.— 20 plants; 17 have flowered, all having normal male flowers.

4^th lot. Seeds of two female flowers of a second plant, which also had 6 petals.—22 plants, of which 7 are flowering, only one of them producing monstrous male flowers.— Some of the 9 plants of the second lot, which had monstrous male flowers, showed this monstrosity only for a short time; the first male flowers were monstrous, but afterwards they produced and are now producing normal male flowers. Gærtner has already observed, that the first flowers (“Erstlingsblumen”) are often distinguished from the later ones by a greater number of stamens or pistils, by greater fertility etc. and I have myself lately observed some curious instances of this.⁹ In a plant of Eschscholtzia the first six or eight flowers had from 5 to 7 petals; afterwards not a single flower with more than 4 petals has appeared on this plant.

On a plant of Siphocampylus the first flowers of several branches had six petals instead of 5; the first of all flowers which this plant produced, had even 7 petals. A few sixpetaled flowers have also appeared among the other flowers of this plant; but these 6 petaled flowers are at least 100 times more numerous among the first flowers of the branches, than among the rest.—

On an umbel of Agapanthus the first flower had 5 segments instead of six.— On a Jussieua,¹⁰ which is extremely common on the banks of the Itajahy, and the flowers of which have normally 4 petals, the first flowers of the branches have not unfrequently 5 petals, and in this case there are generally also 5 sepals, 10 stamens and a 5 locular germen; but in one single flower there were 6 sepals, 5 petals, 10 stamens and a 4 locular germen.—

—To the list of self-impotent plants I may now add Tabernæmontana echinata, on which I lately tried some experiments. A Calonyction with very large white flowers appears to be self-impotent also;¹¹ at least a plant in my garden is quite sterile with its own pollen; but I have no second plant and am therefore unable to say, whether it would be fertile with pollen of a distinct plant.—

A very strange case of graft-hybrids is recorded in one of the last numbers of the “Auxiliador da Industria nacional” (April 1869 pg 158). A “fazendeiro” of the province of Rio de Janeiro, Señr J. F. Silveira da Motta, says that he has obtained a green and red striped variety of sugar-cane by planting close together plants of the green and of the red sugar-cane; as well as yellow and red striped sugar-cane by planting in the same hole cuttings of yellow and of red sugar-cane.¹² I confess that I have some doubts, whether these statements may be trusted; but I hope that I shall soon be able to repeat the experiments of Señr Silveira da Motta.

Permit me to repeat my thanks for all your kindness and believe me, dear Sir, with profound respect

very truly yours | Fritz Müller.