Vegetable Teratology. Maxwell T. Masters
triple flower of Calanthe vestita sent me by Dr. Moore, of Glasnevin, in which all the parts usually existing in three separate flowers were to be found, with the exception of the spur belonging to the labellum of the middle flower (figs. 15, 16).
One of the most common malformations in the Foxglove (Digitalis) results from the fusion of several of the terminal flowers into one. In these cases the number of parts is very variable in different instances; the sepals are more or less blended together, and the corollas as well as the stamens are usually free and distinct, the latter often of equal length, so that the blossom, although truly complex, is, as to its external form, less irregular than under natural circumstances. The centre of these flowers is occupied by a two to five-celled pistil, between the carpels of which, not unfrequently, the stem of the plant projects, bearing on its sides bracts and rudimentary flowers. (See Prolification.) An instance of this nature is figured in the 'Gardeners' Chronicle,' 1850, p. 435, from which the cut (fig. 17) is borrowed.
Fig. 17.—Synanthy and other changes in a Foxglove.
One of the most singular recorded instances of changes connected with fusion of the flowers is that cited by Reinsch,[43] where two female flowers of Salix cinerea were so united with a male one as to produce an hermaphrodite blossom.
It follows, from what has been said, that the number of parts that are met with in these fused flowers varies according to the number of blossoms and of the organs which have been suppressed. Comparatively rarely do we find all the organs present; but when two flowers are united together we find every possible variety between the number of parts naturally belonging to the two flowers and that belonging to a single one. Sometimes instances are met with wherein the calyx does not present the normal number of parts, while the other parts of the flower are in excess. I have seen in a Calceolaria a single calyx, with the ordinary number of sepals, enclosing two corollas, adherent simply by their upper lips, and containing stamens and pistils in the usual way. In this instance, then, the sepals of one flower must have been suppressed, while no such suppression took place in the other parts of the flower.
Professor Charles Morren paid special attention to the various methods in which the flowers of Calceolarias may become fused, and to the complications that ensue from the suppression of some parts, the complete amalgamation of others, &c. Referring the reader to the Belgian savant's papers for the full details of the changes observed, it is only necessary to allude to a few of the most salient features.
Fig. 18.—Synanthic flowers of Calceolaria in which, with two upper lips, there was but a single lower one.
Sometimes the upper lips of two flowers are fused into one, the two lower remaining distinct. In other cases, the upper lip disappears altogether, while there are two lower lips placed opposite one another;, of the stamens, sometimes the outermost, at other times the innermost disappear.[44]
Occasionally there appears to be, as it were, a transference of the parts of one flower to another. One of the simplest and most intelligible cases of this kind is recorded by Wigand in the 'Flora' for 1856, in a compound flower of Polygonatum anceps, in which within a twelve-parted perianth there were twelve stamens and two pistils, one four-celled, the other two-celled; hence it would appear as if a carpel belonging to one flower had become united to those constituting the pistil of the adjacent one. Among Orchids this fusion of some of the elements of different flowers, together with the suppression of others, is carried to such an extent as to render the real structure difficult to decipher. Sometimes flowers of Ophrys aranifera, at first sight seeming normal as to the number, and almost so as regards the arrangement of their parts, have yet, on examination, proved to be the result of a confluence of two flowers. Mr. Moggridge has observed similar phenomena in the same species at Mentone.
Sometimes the fusion affects flowers belonging to different branches of the same inflorescence, as in Centranthus ruber, described by Buchenau, 'Flora,' 1857, p. 293, and even a blossom of one generation of axes may be united with a flower belonging to another generation. Thus M. Michalet[45] speaks of a case wherein the terminal flower of Betonica alopecuros was affected with Peloria, and fused with an adjacent one belonging to a secondary axis of inflorescence, and not yet expanded. This latter flower had no calyx, but in its place were three bracts, surrounding the corolla; this again was united to the calyx of the terminal bloom in a most singular manner, the limb of the corolla and that of the calyx being so joined one to the other as to form but a single tube. It is not uncommon, as has been before stated, to find two corollas enclosed within one calyx, but this is probably the only recorded instance of the fusion of the calyx and corolla of two different flowers belonging to two different axes.
From the preceding details, as well as from others which it is not necessary to give in this place, it would appear that synanthy is more liable to occur where the flowers are naturally crowded together[46] than where they are remote; so too, the upper or younger portions of the inflorescence are those most subject to this change. In like manner the derangements consequent on the coalescence of flowers are often more grave in the central organs, which are most exposed to pressure, and have the least opportunities of resisting the effects of that agency, than they are in the outer portions of the flowers where growth is less restricted.
Morren in his papers on synanthic Calceolarias, before referred to, considers that the direction in which fusion acts is centripetal, e.g. from the circumference towards the centre of the flower, thus reversing the natural order of things. He considers that there is a radical antagonism between the normal organizing forces and the teratological disorganizing forces, and explains in this way the frequent sterility of monsters from an imperfect formation of stamens, or pistils, or both.
The greater tendency in synanthic flowers of parts of one whorl to adhere to the corresponding organs in another flower has often been remarked, though the dislocation of parts may be so great as to prevent this from being carried out in all cases. It appears also that synanthy is more frequently met with among flowers which have an inferior ovary than in those in which the relative position of the organ in question is reversed. This remark applies particularly to individual cases; the proportion as regards the genera may not be so large. The explanation of this must of course depend on the circumstances of each particular case; and it would be wrong to attempt to lay down a general rule, when organogenists have not yet fully decided in what plants the inferior ovary is an axial structure, and in what others the appearance is due to the adhesion of the base of the calyx to the carpels.
The list which follows is not intended as a complete one, but it may serve to show what plants are more particularly subject to this anomaly; the * indicates unusual frequency of occurrence, the ! signifies that the writer has himself seen instances in the plants named. Many of the recorded cases of Synanthy are really cases of adhesion of the inflorescence rather than of the flowers.
Ranunculus Lingua.bulbosus!
Aconitum Napellus.
Delphinium sp.!
Matthiola incana!
Arabis sagittata.
Silene sp.
Reseda odorata!
Vitis vinifera.
Citrus aurantium.
*Fuchsia var. hort.!
Œnothera sp.
Saxifraga sp.
Podalyria myrtillifolia.
Prunus