348 



OEGANOGEAPHY. 



Section 8. — Symmetey of the Flo wee. 



The terra symmetry has been variously understood by dif- 

 ferent authors. As properly applied, a symmetrical flower is 

 one in which each whoii of organs has an equ.al number of 

 parts ; or where the parts of one whorl are multiples of those of 

 another. Thus in some species of Crassula {fig. 766), we 

 have a symmetrical flower composed of five sepals, five petals, 

 five stamens, and five carpels ; in Sedum {fig. 767), we have 

 five sepals, five petals, ten stamens in two rows, and five 

 carpels ; in the Elax, we have five sepals, five petals, five 

 stamens, and five carpels, each of which is partially divided 



Fig. 766. 



Fig. 767. 



Fiff. 766. Flower of Crassula ruhens. c, c. Sepals, p, p. Petals, e, e, e. 

 Stamens, o, o. Carpels, at the base of each of which is seen a scale, 

 a, a. Fig. 767. Flower of Sedum. 



into two by a spurious dissepiment {fig. 604) ; in the Circcsa 

 {fig. 768), we have two organs in each whorl; in the Kue 

 (figs. 56-1 and 597), we have four or five sepals, four or five 

 petals, eight or ten stamens, and a four or five-lobed pistil ; and 

 in the Iris, there are three organs in each whorl. All the above 

 are therefore symmetrical flowers. When the number of parts in 

 each whorl does not correspond, or when the parts of a whorl 

 are not multiples of one another, the flower is unsymmetrical, as 

 in Verbena {fig. 388), where the calyx and corolla have flve 

 parts in each whorl, and the andrcecium and gyncecium only 

 four. 



A symmetrical flower, in which the number of parts in each 

 whorl is the same, as in Crassula {fig. 766), is said to be 

 isomerous ; or when the number is unequal, as in Eue {figs. 564 

 and 597), and Sedum {fig. 767), the flower is anisomerous. 

 The number of parts is indicated by a Greek numeral prefixed 

 to the word m ros, signifying a part. Thus when there are two 

 parts in the whorls, as in Circcea {fig. 768), the flower is 



