Chapter 2 



THE INFLORESCENCE 



Flowers are borne singly and in clusters. Those in clusters, together 

 with the stems and bracts associated with them, form inflorescences; 

 those borne singly are termed solitary flowers. 



Solitary flowers may terminate shoots of major or of minor rank, or 

 may be axillary. In the terminal position, some solitary flowers may 

 represent a simple and primitive condition; for example, in primitive 

 woody genera such as those of Magnolia, Annona, Eupomatia, Calij- 

 canthus. Others, the great majority, are doubtless surviving members 

 of reduced inflorescences, some derived from terminal, some from 

 axillary clusters. SoHtary axillary flowers are commonly surviving units 

 of axillary clusters. 



It is difficult to draw a line between a group of solitary flowers and 

 an inflorescence. The limits of inflorescences are often poorly defined; 

 specialized inflorescences of various types pass downward into flowers 

 — solitary or in small clusters — in the axils of foliage leaves — for ex- 

 ample, in Lijsimachia, Campanula. Obviously, a definition for inflores- 

 cence that will satisfactorily describe and limit all flower clusters called 

 inflorescences cannot be made. The inflorescence is not a morphological 

 unit; it is a part of the branching system of the stem with more or less 

 definitely segregated flowering tips. In the long course of specialization 

 of the angiosperms, the inflorescence has been morphologically modified 

 in many ways, with the production of similar form in unrelated lines. 

 Under extreme specialization, some inflorescences no longer resemble 

 branch systems but flowers and fruits — Compositae (Figs. 28 and 37), 

 Proteaceae, Urticaceae. Inflorescences may be grouped in larger in- 

 florescences, and these may be reduced, as in the smaller herbaceous 

 species of Euphorbia. 



Inflorescences range in size from minute to huge, and in flower num- 

 ber up to millions. The multiflowered panicles of the grasses and the 

 heads (often compound) of some Compositae are well known examples. 

 The terminal inflorescence of Corypha wnhraculifera, a monocarpic 

 palm, is a pyramidal panicle* about 10 m high and about 1 m in 

 diameter at the base, with a flower number estimated at 6,000,000. The 



" The term panicle is here used in the broader sense, for any large, compound 

 inflorescence, determinate, indeterminate, or mixed in type. 



67 



