ORGANS OF EEPKODUCTION. 199 



on such an axis they must necessarily arise from axillary buds 

 placed below the terminal flower-bud, and if these form secondary 

 axes {fig. 406, a") each axis will in like manner be arrested in 

 its growth by a terminal flower-bud /''', and if other axes a'" are 

 developed from the secondary ones, these also must be axillary, and 

 will be arrested in a similar manner by flowers/'", and these axes 

 may also form other axes of a like character, and so on. Hence 

 this mode of inflorescence is det.'rrninate, definite, or terminal, in 

 contradistinction to the former or indefinite mode of inflorescence 

 already 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 

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

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

 406). In definite inflorescences the flower-buds necessarily 

 follow a different order of expansion from those of indefinite 

 inflorescences, because in them the terminal flower is the first 

 developed and consequently the oldest {fig. 406, f), and other 

 flower-buds are produced in succession from the apex to the base, 

 if the axis be elongated (^^.406,/",/'"); or if depressed or dila- 

 ted, from the centre to the circumference. The uppermost flower- 

 bud of the elongated axis {fig. 406,/'), and the central one of the 

 depressed or dilated axis will accordingly open first, and the lower- 

 most 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 characterised by a centripetal 

 order of expansion, those of definite inflorescences are centrifugal. 

 Kinds of Definite Infiorescence . — The general name of cyme 

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

 distinguished by special names : — 



Fig. 407. 



?ig. 407. Cyme of Laurustiaus {yiburnum Tinus), 



