[page] 551

XXXIII. On the Identity of three supposed Genera of Orchideous Epiphytes. In a Letter to A. B. LAMBERT, Esq., V.P.L.S. By Mr. ROBERT H. SCHOMBURGK.

Read November 15th, 1836.

IN a letter which I had the pleasure to address to Mr. Bentham, on the 28th of June last year, I informed him of a remarkable Orchideous plant, from appearance a Monachanthus, which on one side of the bulb produced a scape with six flowers of Monachanthus viridis, and two of the Myanthus barbatus, while a second scape of the same bulb had twenty-five blossoms of the Myanthus barbatus. This plant was in possession of Mr. Reiss, who, when both scapes were in full flower, took the accompanying drawing (TAB. XXIX.) of it, and preserved the stem with the flowers of Monachanthus viridis and Myanthus barbatus in spirits, which I have likewise the pleasure to send herewith, and beg you to present it in my name to the Linnean Society.

If the circumstance of a bulb of the Monachanthus producing conjointly the flowers of its own genus and Myanthus had occurred only in this instance, it might be considered one of those freaks of Nature which not unfrequently occur; but the case just quoted is not singular, and has been observed at least once more in a collection of Orchideous plants belonging to a lady, where the same species of Monachanthus produced also flowers of the Myanthus barbatus.

The thought impresses itself, therefore, forcibly upon me, that the genera Monachanthus, Myanthus, and Catasetum form but one genus, and in this conclusion I am borne out by the following observations.

A vigorous plant, which produced at its former state of inflorescence the flowers of Monochanthus viridis, had two months ago a scape with flowers of Catasetum tridentatum; this occurred at Mr. Wortman's collection at Canal, No. 1.

Mr. Bach, an enthusiastic collector of Orchideous plants, sowed the seed

[page] 552

of Monachanthus viridis on a decayed trunk of an Erythrina. Among these plants, one produced a scape with the flowers of Catasetum tridentatum: this I saw myself: the bulb was young, but the flowers in every respect quite perfect.

Here we have traces of sexual difference in Orchideous flowers. I have seen hundreds of Catasetum tridentatum on savannahs adjacent to the lake Capoeya (Arabisee coast of Essequebo), without ever finding one specimen with seeds, while those bulbs which, according to Dr. Lindley's description, belonged to Monachanthus viridis, astonished me by their gigantic seed-vessels.

Mr. Bach raised from the seeds of Monachanthus viridis a plant of Catasetum, and I have observed individually scapes which bore flowers of both genera, while the evidence of the present plant, which has caused these remarks, would likewise include the genus Myanthus in the group. Dr. Lindley appears to have been prepared for the latter discovery in his Genera and Species of Orchideous Plants, part iii. p. 155. In his diagnosis of Myanthus, he says "anthera et pollinia Cataseti;" and further on, "Catasetum cristatum is intermediate between this genus and Catasetum:" but I doubt whether he ever conjectured the near relationship between Monachanthus and Myanthus, and the terms "labellum posticum" and "anticurn" will be hereafter of less value as generic differences.

Demerara, August 15, 1836.

[plate]