208 



ORGANOGRAPHY. 



the Hydrangea; or more or less spreading as in the Chickweed 

 (Jig. ill). In the more perfect and compact form of cyme, as 

 found in the Laurustinus, Elder, &c., the flower-buds are all 

 perfect before any of them open, and then the flowering takes 



]3lace rapidly, commenc- 



Fig. 411. 



Fig. 411. Cyme of a species of Chickweed 

 {Cermtium). a', a'. Primary axis ter- 

 minated by a flower, a", a". Secondary 

 axes, arising from the axils of opposite 

 bracts h, and terminated also by flowers. 

 a'", "'", a'". Tertiary axes, arising from 

 hra'cts b. and bearingothcr bracts b, from 

 which other axes arise a"", a"", a"". 



mg in the centre of the 

 cyme, and then in the 

 centre of each of its di- 

 visions, and thence pro- 

 ceeding in an outward 

 direction ; and as the 

 central flower of each 

 cluster corresponds to 

 the apex of each branch, 

 the expansion of the 

 whole is centrifugal. By 

 attention to this order of 

 expansion such cymes 

 may be always distin- 

 guished from indefinite 

 kinds of inflorescence, 

 such as the umbel, or 

 corymb, to which other- 

 wise they bear in many 

 cases a great resem- 

 blance. In the Chick- 

 weed (Jig. 411), and 

 many other plants, the 

 formation of the second- 

 ary and other axes a" 

 a'" a"" goes on through- 



out the growing season, 

 and in such cymes, which 

 are usually of a more 

 or less .'spreading nature 

 the centrifugal or ct/mose 

 (as it is also called) order of expansion may be well observed. 

 The above cymes are also characterised as dichotomous, or tricho- 

 tomom, according to the number of their brandies, thus they are 

 dichotomous, as in the common Centaury (Erythrcca Centau- 

 rium) (Jig. 412), when the primary axis a' is terminated l)y a 

 flower./"', at the base of which are two bracts, each of whicli de- 

 veloiies in its axil secondary axes a" a'', ending in single 

 flowers, /" /"; and at the base of each of these flowers 

 there are also two other bracts, from wliich tertiary axes 

 a'" a'" a'" arc developed, also terminated by flowers /'" 

 ' f" f" a"*^ ^o o"' ^"^^ ^^ ^''^ division in this case always takes 

 place into two branches, the cyme is said to be dicholomous. It' 



