=Adhesion of the stamens to the petals= is of common occurrence under natural circ.u.mstances. Ca.s.sini has described a malformation of _Centaurea collina_, in which two of the five stamens were completely grafted with the corolla, the three others remaining perfectly free.

Adhesion of the petals to the column is not of infrequent occurrence among Orchids. I have observed cases of the adhesion of the segments of the perianth to the stamen in _Ophrys aranifera_, _Odontoglossum_, _sp_.

&c. It is the ordinary condition in _Gongora_ and some other genera. I have seen it also in _Lilium lancifolium_. Some forms of _Crocus_, occasionally met with, present a very singular appearance, owing to the adhesion of the stamens to the outer segments of the perianth, the former, moreover, being partially petaloid in aspect. M. de la Vaud[35]

speaks of a similar union in _Tigridia pavonia_. Morren[36] describes a malformation of _Fuchsia_ wherein the petals were so completely adherent to the stamens, that the former were dragged out of their ordinary position, so as to become opposite to the sepals; the fusion was here so complete that, no trace of it could be seen externally. It should be remarked that it was the outer series of stamens that were thus fused.[37]

[Ill.u.s.tration: FIG. 12.--_Crocus._ Adhesion of petaloid stamens to perianth.]

=Adhesion of stamens to pistils.=--The stamens also may be united to the pistils, as in gynandrous plants. Moquin speaks of such a case in a _Scabious_; M. Clos in _Verbasc.u.m australe_.[38] I have seen cases of the same kind in the Wallflower, Cowslip (_Primula veris_), Tulip, Orange, in the garden Azalea and other plants.

=Miscellaneous adhesions.=--Sometimes organs, comparatively speaking, widely separated one from the other, become united together. Miquel has recorded the union of a stigma with the middle lobe of the lower lip of the corolla of _Salvia pratensis_.[39] In the accompanying figure [fig.

13], taken from a double wallflower, there is shown an adhesion between a petal and an open carpel on the one side, and a stamen on the other.

Moquin speaks of some pears, which were united, at an early stage, with one or two small leaves borne by the peduncle and grafted to the fruit by the whole of their upper surface. As the pear increased in size the leaves became detached from it, leaving on the surface of the fruit an impression of the same form as the leaf, and differing in colour from the rest of the surface of the fruit. Traces of the princ.i.p.al nerves were seen on the pear.

[Ill.u.s.tration: FIG. 13.--_Cheiranthus cheiri_. Adhesion of petal to stamen and open carpel.]

It is curious to notice how very rare it is for the calyx to adhere to the ovary in flowers where that organ is normally superior. The "_calyx inferus_" seems scarcely ever to become "_calyx superus_," while, on the other hand, the "_calyx normaliter superus_" frequently becomes inferior from detachment from, or from want of union with the surface of the ovary.

=Adhesion of fruit to branch.=--Of this Mr. Berkeley[40] cites an instance in a vegetable marrow (_Cuc.u.mis_), where a female flower had become confluent with the branch, at whose base it was placed, and also with two or more flowers at the upper part of the same branch, so as to make an oblique scar running down from the apex of the fruit to the branch.

=Synanthy.=--Adhesion of two or more flowers takes place in various ways; sometimes merely the stalks are united together, so that we have a single peduncle, bearing at its extremity two flowers placed in approximation very slightly adherent one to the other. In this manner I have seen three flowers of the vegetable marrow on a common stalk, the flowers themselves being only united at the extreme base. Occasionally cases may be met with wherein the pedicels of a stalked flower become adherent to the side of a sessile flower. I have noticed this commonly in _Umbelliferae_. Union of this kind occurs frequently in the common cornel (_Cornus_), wherein one of the lower flowers becomes adherent to one of the upper ones. In De Candolle's 'Organographie Vegetale,' Plates 14 and 15, are figured cases of fusion of the flower stems of the Hyacinth and of a _Centaurea_. In other cases the union involves not only the stalk but the flowers themselves; thus fusion of the flowers is a common accompaniment of fasciation, as was the case in the _Campanula_ figured in the cut (fig. 14).

[Ill.u.s.tration: FIG. 14.--Synanthic flowers of _Campanula medium_.]

Synanthy may take place without much derangement of the structure of either flower, or the union may be attended with abortion or suppression of some of the parts of one or both flowers. Occasionally this union is carried to such an extent that a bloom appears to be single, when it is, in reality, composed of two or more, the parts of which have become not only fused, but, as it were, thrust into and completely incorporated one with another, and in such a manner as to occupy the place of some parts of the flower which have been suppressed. It must not be overlooked that this adhesion of one flower to another is a very common occurrence under natural circ.u.mstances, as in _Lonicera_, in the common tomato, in _Pomax_, _Opercularia_, _Symphyomyrtus_, &c., while the large size of some of the cultivated sunflowers is in like manner due to the union of two or more flower-heads.

One of the simplest instances of synanthy is that mentioned by M.

Duchartre,[41] in which two flowers of a hyacinth were united together simply by means of two segments of the perianth one from each flower. A similar occurrence has been cited by M. Gay in _Narcissus chrysanthus_.

In like manner the blossoms of Fuchsias or Loniceras occasionally become adherent merely by their surface, without involving any other change in the conformation of the flowers. M. Maugin alludes to a case of this kind in _Aristolochia Clemat.i.tis_.[42]

But it is more usual for some of the organs to be suppressed, so that the number of existing parts is less than would be the case in two or more uncombined flowers. A few ill.u.s.trations will exemplify this. In two flowers of _Matthiola incana_, that I observed to be joined together, there were eight sepals, eight petals, and ten perfect stamens, eight long and two short, instead of twelve. Closer examination showed that the point of union between the two flowers occurred just where, under ordinary circ.u.mstances, the two short stamens would be. In this instance but little suppression had occurred. In similar flowers of _Narcissus incomparabilis_ I remarked a ten-parted perianth, ten stamens within a single cup, two styles, and a five-celled ovary. Here, then, it would appear that two segments of the perianth, two stamens, and one carpel were suppressed. In a Polyanthus there were nine sepals, nine petals, nine stamens, and a double ovary.

[Ill.u.s.tration: FIG. 15.--Union of three flowers of _Calanthe vest.i.ta_.]

[Ill.u.s.tration: FIG. 16.--Shows the abortion of the central spur in synanthic flowers of _Calanthe vest.i.ta_.]

As an ill.u.s.tration of a more complicated nature reference may be made to three flowers of _Aconitum Napellus_, figured by A. de Chamisso, 'Linnaea,' vol. vii, 1832, p. 205, tab. vii, figs. 1, 2. In this specimen the two outer blossoms had each four sepals present, namely, the upper hooded one, one of the lateral sepals, and both of the inferior ones; the central flower had only the upper sepal and one other, probably one of the lower sepals; thus there were but ten sepals instead of fifteen.

The nectary-like petals, the stamens, and pistils were all present in the lateral flowers, but were completely suppressed in the middle one. A less degree of suppression was exemplified in a triple flower of _Calanthe vest.i.ta_ 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 circ.u.mstances. 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.

[Ill.u.s.tration: 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.

[Ill.u.s.tration: 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 const.i.tuting 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 circ.u.mference 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 circ.u.mstances 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.!

OEnothera sp.

Saxifraga sp.

Podalyria myrtillifolia.

Prunus Armeniaca.

spinosa.

Pyrus Malus.

Persica vulgaris.

Crataegus monogyna.

Robinia pseudacacia.

Gleditschia triacanthos.

Syringa persica.

Cornus sanguinea.

Viburnum sp.

*Lonicera sp. plur!

Centranthus ruber!

Valantia cruciata.

Centaurea moschata.

Jacea.

Zinnia elegans.

Zinnia revoluta.

Helianthus sp.!