PLEIOTAXY. 371 



Coniferas, which he considers to be improperly termed 

 polycotyledonous. Whether this holds good in the 

 Loranths, where (Nmjtsia, Fsittacanthus) an appearance 

 of polycotyledony exists, is not stated. In the case of 

 the rue (Ruta) figured by M. A. de Jussieu^ this 

 sphtting of one cotyledon into two is sufficiently evi- 

 dent, as is also the case in the sycamore (Acer pseudo- 

 platanus)j seedlings of which may often be met with 

 divided cotyledons. 



In other instances a fusion of two embryo plants 

 may give rise to a similar appearance, as in the 

 Euphorhia and Sinapis found by M. Alph. de Candolle 

 (see ante, p. 56). 



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 Engel- 

 mann, 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 Mcesn, and in a peculiar variety of carnation, called 

 the wheat-ear carnation.^ In some of these cases the 

 increase in the number of bracts is attended by a cor- 

 responding suppression in the other parts of the flower. 

 Such a condition has been frequently met with in 

 Gentiana AvmreUat where the bracts are increased in 



' Mem. Mus.,' xii, t. 17. 



3 * Nov. Act. Acad. Nat. Cur.,' xv, tab. xxviii, f. 3 ; ' Bot Mag./ t. 1622. 

 " Caryophyllus spicain frumenti referens." A similar malfonnation in 

 Dianthus barhattia is not uncommon. It has lately been introduced into 

 gardens under the name of Dianthua " mousaeux," but is not likely to 

 find favour with gardeners. 



