DICOTYLEDONS. 



569 



When a flower has more stamens than sepals or petals, this may be the result, 

 as has already been mentioned, on the one hand of an increase in the number of 

 staminal whorls (as in Fig. 420), or on the other hand, of the interposition of 

 a perfect or imperfect whorl among the typical ones, or of dedoublement of the 

 stamens (as in Fig. 427). These cases must be clearly distinguished from those in 

 which a larger number of stamens results from the branching of the original ones, 

 a phenomenon which is found in different sections of Dicotyledons, and is some- 

 times constant in whole families (see p. 475). Thus, for instance, in DiUeniaceas 



I'"IG. 427. — niat;r.-im of scl 

 (Paronychiace.-c). 



Fig. 428. — Diagram of Phytolacca 

 (Phytolaceacepe). 



I'lG. 429. — Diagram of Celosia 

 {Amaranthacese). 



(Fig. 430), Aurantiaccx (P'ig. 431), and Tiliacene (Fig. 432), each symbol which 

 indicates a group of anthers corresponds to a single original stamen. In this case 

 the number of original stamens is the same as that of the petals and sepals ; 

 but sometimes it is less (as in Hypericum perforatum with three staminal bundles 

 in the pentamerous flower) ; so that an increase in the number of stamens is 

 united with a decrease of the typical number of staminal leaves. 



The branching of carpels is much less common than that of stamens. It 

 occurs very clearl}' in Malvaceae, where the typical number of carpels is five, 



Fig. 430. — niigram of Candollea 

 (Dilleniacca-). 



FIG. 43t —Diagram of Citrus 

 (Aurantiacese). 



FIG. 432.— Diagram of Tiliaceffi. 



and they are often developed as such (as in Hibiscus). In some genera however 

 (as Malva, IMalope, and Althaea) five original rudiments of carpels first of all 

 make their appearance in the form of a low cushion. Each of these forms very 

 early a larger number of outgrowths lying side by side, and each of these produces 

 a style and a one-seeded compartment of the peculiarly-shaped gynaeceum^ 



This short sketch will be sufficient to show what variations are possible in 

 the numbers and positions of the parts that may be included under the expression 

 Cn (_m)5 which, as has already been said, is especially characteristic 



'^n Pn St. 



n "^ni {+n+. . .) ^n ( 



of flowers with pentamerous or truly tetramerous whorls. True tetramerous flowers 



^ See Payer, Organogenic dc la fleur, Tl. 6 8. 



