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.

In addition to the works before cited, additional information on this subject may be gained from the following:—Jaeger, 'Missbilld.,' p. 92. v. Schlechtend, 'Bot. Zeit.,' 1856, Robinia. Weber, 'Verhandl. Nat. Hist. Vereins. Preuss. Rheinl.,' 1849, p. 290, Primula. Hincks, 'Rep. Brit. Assoc. Newcastle,' 1838, Salpiglossis. Clos, 'Mém. Acad. Toulouse,' vol. vi, 1862, Anagallis. Wigand, 'Flora,' 1856, tab. 8, Pedicularis. Henfrey, 'Botan. Gazette,' i, p. 280, Reseda. P. Reinsch, 'Flora,' 1860, tab. 7, Petasites. Weber, Verhandl. Nat. Hist. Vereins. f.d. Preuss. Rheinl. u. Westphal.,' 1860, p. 332, tabs. 6 et 7, Prunus, Persica, Campanula, Taraxacum, Saxifraga, Silene, Hyacinthus, &c. Miquel, 'Linnæa,' xi, p. 423, Colchicum. Michel, 'Traité du Citronnier,' tab. 6, Citrus.

Syncarpy.—In the preceding section it has been shown that the carpels, like other parts of the flower, are subject to be united together. This union may either take place between the carpels of a single flower or between the pistils of different flowers. In the latter case the other floral whorls are generally more or less altered. Where, however, the ovary is, as it is called, inferior, it may happen that the pistils of different flowers may coalesce more or less without much alteration in the other parts of the flower, as happens normally in many Caprifoliaceæ, Rubiaceæ, &c. &c. In some of these cases it must be remembered that the real structure of the apparent fruit is not made out beyond dispute, the main points of controversy being as to what, if any, share the dilated fruit-stalk or axis takes in the formation of such organs. Again, it will be borne in mind that in some cases the so-called fruit is made up of a number of flowers all fused together, as in the Mulberry or the Pineapple, in which plants what is, in ordinary language, called the fruit really consists of the whole mass of flowers constituting the inflorescence fused together. Union of the fruits may also in some cases take place between the carpels after the fall of the other floral whorls, particularly when the outer layers of the pericarp assume a succulent condition, so that under the general head of syncarpy really different conditions are almost necessarily grouped together, and, in seeking to investigate the causes of the phenomenon, the particular circumstances of each individual case must be taken into account. Syncarpy takes place in various degrees; sometimes only the stalks are joined; at other times the whole extent of the fruit, as in cherries, &c. This peculiarity did not escape the observant mind of Shakespeare—

"A double cherry seeming parted.

But yet a union in partition,

Two lovely berries moulded on one stem."