ORGANS OF REPRODUCTION. 207 



ready described, where the primary axis elongates indefinitely 

 unless stopped by some extraneous cause. Definite inflorescences 

 are most common and regular in plants with opposite or 

 Avhorled leaves, but they also occur in those which have alter- 

 nate leaves, as for instance in the Buttercup (Ranunculus) {fig. 

 409), and the Columbine (Aquilegia vulgaris). In definite in- 

 florescences Ave have a difl'crent order of unfolding in the flower- 

 buds to those of the indefinite, because in them the terminal 

 flower is the first dcA'eloped and consequently the oldest (fig. 

 409 /'), and other buds are produced in succession from the 

 apex to the base, if the axis be elongated {fig. 414), or if de- 

 pressed or dilated, from the centre to the circumference. The 

 uppermost flower-bud of the elongated axis, and the central one 

 of the depressed or dilated axis will accordingly open first, 

 and the lowermost of the former, and the most external of the 

 latter, last. Such an order of expansion is called centrifugal. 

 Hence while the indefinite kinds of inflorescence are charac- 

 terised by a centripetal order of expansion, those of definite in- 

 florescences are centrifugal. 



Kinds of Definite Inflorescence. — The general name of cyme 

 is applied to all such inflorescences, but a few of them are also 

 distinguished by special names •' — 



a. The true Cyme. — This term is commonly applied by 

 botanists to a definite inflorescence Avhich is more or less 

 branched, the whole being developed in a corymbose manner, 

 and thus assuming a somewhat flattened head, as in the Laurus- 

 tinus {fig. 410) Dogwood and Elder; or a rounded one, as in 



Fig. 410. 



Fig. 410. Cyme of Laurustinus (^Viburnum Timis). 



