=Petalody of the calyx--Calycanthemy.=--As with the bracts, so the calyx in certain instances is naturally coloured, as in _Delphinium_, _Tropaeolum_, and others. In _Mussaenda_, _Calycophyllum_, _Usteria_, &c., one or more of the calyx lobes become enlarged normally. Considered teratologically, petaloid coloration of the sepals is either general or partial; in the latter case the nerves retain their green colour longest. There is in cultivation a variety of the primrose called _Primula calycanthema_, in which the upper part of the calyx becomes coloured, so that the flower seems to have two corollas placed one within the other; a similar thing happens in _Mimulus_, in which plant, as the calyx is permanent while the corolla is deciduous, the coloured calyx is a great advantage in a horticultural point of view. Morren[296] says that in order to produce the fine colour of the calyx of _Primula officinalis_ (var. _smaragdina_) the Belgian gardeners cut away the corolla in a very early stage, and that in consequence the colouring matter proper to the corolla is developed in the tube of the calyx, the edges of the limb remaining green, the middle of the limb being purple (_Primula tricolor_). [Illustration: FIG. 153.--Flower of _Mimulus_, with petaloid calyx.] Under this head may be mentioned the occurrence of tubular sepals in place of the ordinary flat ones in _Helleborus olympicus_; only two of the sepals were thus affected in a specimen recently observed--a third exhibited an intermediate condition. The normal coloration of the calyx occurs most frequently in polysepalous calyces; teratological coloration, on the other hand, occurs especially in gamosepalous flowers. This assertion is borne out by the frequency of the change in the plants already mentioned, and also in the following:--_Campanula persicifolia_, _Anagallis arvensis_, _Gloxinia_, _Syringa persica_,[297] _Calceolaria_, _&c. &c_. In the last-named plant one or more of the lobes of the calyx may frequently be seen replaced by a slipper-like petal. Among polysepalous plants petaloid sepals have been observed in _Ranunculus auricomus_, _Rubus caesius_, _&c._ Fleischer also describes a case of this kind in _Carum carui_.[298] It will be seen from the above that in the majority of cases there is no real metamorphosis or substitution of petal for calyx, but simply an alteration in colour; nevertheless, a change in form may accompany a change of colour: this happens especially if there has been any displacement of organs. Thus, if, in an orchidaceous plant, a sepal be displaced from any cause, or a petal be twisted out of its natural position to occupy the place of an absent sepal, that petal will be sepal-like in form, and _vice versa_. =Petalody of the stamens.=--A petaloid condition of the stamens is one of the commonest of all malformations. A large number of so-called double flowers (flores pleni)[299] owe their peculiar appearance to this circumstance.