Fig. 192.—Diagram showing the arrangement of parts in an orchid flower. According to Crüger, the stamens A 2, A 3, should be distinct from the lip. The uppermost figure 2 should have been 1. (See text.)
In either case it is admitted that there are six stamens in two rows. The first row consists of one posterior stamen, which is generally perfect, and two abortive stamens incorporated with the labellum. The second row also consists of three stamens, all of which are usually abortive and inseparable from the column. Traces of them may occasionally be met with in the form of tubercles or wing-like processes from the column. In Cypripedium, while the ordinary stamen of the outer row is deficient, two of the inner series are present. The diagram, fig. 192, will serve to show the arrangement of the parts as above described. + represents the situation of the stem or axis; on the opposite side is the bract; between these are placed the sepals, one posterior or next the axis (incorrectly numbered 2 in the plan), two lateral 1, 1; next in order follow the petals, 2, 2, 2, two lateral and somewhat posterior, one larger (the lip), anterior; the outer series of stamens are represented by A 1, A 2, A 3, the two latter being fused with the labellum; a 1, a 2, a 3 represent the position of the inner verticil of stamens, while s, s, s denote the three carpels. It is foreign to the purpose of this book to detail the varied evidence in support of this explanation of the homologies of orchid flowers.[438] All that can be done in these pages is to set forth the evidence furnished by teratology as to this matter—evidence for the most part accumulated and recorded without any special reference to any theory of orchid structure.
The following details all refer to flowers in which the number of stamens in orchidaceous plants was increased beyond what is necessary. They are arranged with reference to the number of adventitious organs, beginning with those in which the number was smallest, and proceeding thence to those in which it was greatest. In some cases it has not been possible to ascertain whether the adventitious organs were really restorations of the numerical symmetry, substitutions of one part for another, stamen for petal, &c., or wholly adventitious productions. Unless otherwise stated, the interpretation put upon the facts thus recorded is that of the present writer, and not necessarily that of the original observer.
Mr. J. T. Moggridge has described and figured a flower of Ophrys insectifera in which there was a vestige of a second stamen present, probably one of the inner series fig. 192 (a2).[439] The same observer also records the presence of a second anther between the lobes of the normal one. This can hardly be referred to either of the typical stamens, but would seem to be a perverted development of the rostellum.[440]
Rœper is stated by Cramer[441] to have seen a specimen of Orchis morio with two stamens.
In a flower of Habenaria chlorantha, described by the late Professor Henslow,[442] the outer three stamens are suppressed, while two of the inner group are present, as happens normally in Cypripedium.
A flower of Cattleya violacea afforded a similar illustration; but in this case only one of the inner stamens was developed, and this in the form of a small petal, partly adherent to the column.
In Dendrobium normale, Falconer, not only is the perianth regular, but the column is triandrous,[443] the three stamens (according to the diagram of its structure given by Lindley) pertaining to the outer row.
In a specimen of Dendrobium hœmoglossum kindly forwarded from Ceylon by Mr. Thwaites there were three stamens present, of which one posterior belonged to the outer series A 1, and two lateral to the inner a 1, a 2, fig. 192.