=Pleiotaxy or multiplication of whorls.=--In the preceding section notice has been taken of the increased number of parts in a single whorl, but an augmentation of the number of distinct whorls is still more frequently met with. Many of the so-called double flowers owe their peculiarity to this condition. The distinction between the two modes in which the parts of the flower are increased in number has been pointed out by Engelmann, Moquin, and others, and the two seem to require distinctive epithets; hence the application of the terms polyphylly and pleiotaxy, as here proposed. =Pleiotaxy in the bracts.=--An increase in the number of bracts has been met with very constantly in a species of _Maesa_, and in a peculiar variety of carnation, called the wheat-ear carnation.[426] In some of these cases the increase in the number of bracts is attended by a corresponding suppression in the other parts of the flower. Such a condition has been frequently met with in _Gentiana Amarella_, where the bracts are increased in number, coloured purple, and destitute of any true floral organs. A similar condition exists in some varieties of _Plantago major_ (var. _paniculata_), as has been previously stated, p. 109. [Illustration: FIG. 187.--Wheat-ear carnation. The appearance is due to the multiplication of the bracts and the suppression of the other parts of the flower.] It has been noticed also in the common pea, _Pisum sativum_, and M. Lortet[427] records a case of the kind in _Erica multiflora_, the flowers of which, under ordinary circumstances, are arranged in clusters, but in this case the pedicels were more closely crowded than usual, and were covered for their whole length with small rose-coloured bracts arranged in irregular whorls, the upper ones sometimes enclosing imperfect flowers. In the 'Gardeners' Chronicle,' 1865, p. 769, is figured a corresponding instance of _Delphinium Consolida_, in which the bracts were greatly increased in number, petaloid, and, at the same time, the central organs of the flower were wholly wanting. [Illustration: FIG. 188.--_Delphinium Consolida_. Multiplication of bracts at the expense of the other parts of the flower.] [Illustration: FIG. 189.--Multiplication of bracts, &c., _Pelargonium_.] In flowers of _Pelargonium_ may occasionally be seen a repetition of the whorls of bracts, in conjunction with suppression and diminished size of some of the other portions of the flower (fig. 189). The common foxglove (_Digitalis purpurea_) has likewise occasionally been observed subject to a similar malformation.