James Small. 
i*4 
THE ORIGIN AND DEVELOPMENT OF THE 
COMPOSITE. 
By Jamhs Small, M.Sc. (Lond.), Ph.C. 
Chapter VI. 
THE INVOLUCRE. 
T HE characters of the involucre have been used more or less 
empirically in various systems of classification, but there 
appears to have been no critical consideration of the origin and 
homologies of this structure. 
As the involucre is present fully developed in practically all 
Compositse it is necessary to consider the evolution of involucral 
structures in other families where its origin and development can 
be traced. This is done in Section B of the present chapter 
which in addition contains a brief account of the history of our 
knowledge of the involucre in the Compositse, an analysis of the 
various types to be found in the family and an indication of the 
bearing of that variation on the previous phyletic conclusions. 
A. History. 
As the involucral bracts are easily observed and show a 
great variety of form they received a considerable share of the 
attention of the earlier systematists. Vaillantus (II, 70') used the 
involucre for his primary divisions of the Cynarocephalse; Magnol 
(I, 62) who used the “calyx” as his basis for classification, 
characterises his “ Compositum ” as “ calice externo includente 
florem ”; Boerhaave (1,12) gives the involucral characters for each 
genus; Linnrf (1,59) gave a “ methodus a calycis ” of his own, 
dividing the “ Communes ” into eight groups on the character of the 
involucre. He distinguished various types of involucre such as 
simple, uniseriate, duplex, calyculate, involucrate, multiseriate with 
all the bracts similar or imbricate. Berkhey at a later date (1,9) 
gave figures of various types of involucral bracts and considered the 
involucre in some detail, distinguishing the simple, imbricate and 
calyculate types. 
The involucre was used with other parts by Don (I, 25) in his 
classification of the Cichorieae, and Gaertner (I, 32), although he 
did not use this structure for his larger groups, described it 
carefully for each genus. The involucre is now included in the 
1 Roman numerals refer to previous bibliographies. 
