ITS SY5IMETRY. 



233 



■(as already defined, 416) is one that possesses both sorts 

 envelopes, calyx and corolla, and both essential organs, viz. 

 and pistils. 



437. The simplest possible complete and 

 symmetrical flower would be one with the ca- 

 lyx of a single sepal, a corolla of a single petal, 

 a single stamen, and a single pistil ; as in the 

 annexed diagram (Fig. 352), which represents 

 the elements of a simple stem (Fig. 157), ter- 

 minated by an equally simple flower. Each 

 constituent of the blossom represents a phyton 

 (163), with its stem part reduced to a mini- 

 mum, and its leaf part developed in a peculiar 

 way, according to the rank it sustains and the 

 office it is to fulfil. That there are short inter- 

 nodes between consecutive organs in the flower 

 is usually apparent on minute inspection of its 

 axis, or receptacle ; and some of them are con- 

 spicuously prolonged in certain cases. But 

 they are commonly so short that the organs 

 are brought into juxtaposition, just as in a leaf- 

 bud, and the higher or later-formed parts are 

 interior or enclosed by the lower. 



438. Perhaps the exact case of a flower at 

 once so complete and so simple is not to be met 

 with, the organs of the flower, or some of 

 them, being generally multiplied. Thus we 

 find a circle or whorl of each kind of organ, 

 and often two or three circles, or a still larger 

 and apparently indefinite number of parts. In 

 fact, the floral organs usually occur in twos, 

 threes, fours, or fives ; and the same number 

 is apt to prevail throughout the several circles 

 of the flower, which therefore displays a sym- ^^^ 

 metrical arrangement, or a manifest tendency towards it.* 



of floral 

 stamens 



* Terms expressive of the number of parts which compose esich whorl of 

 kind of organ — which are sometimes very convenient to use — are formed of 



FIG. 352 Diagram of a pla&t, with a distichous arrangement of the phytons, carried 

 through the complete flower, of the simplest kind, consisting of, a, a sepal ; &, a petal ; c, a 

 stamen ; and d^ a pistil : br is the bract or uppermost proper leaf. 



20* 



