THE EVOLUTION OF THE INFLORESCENCE. . 511 
The Evolution of the Inflorescence. 
By J. Parkin, M.A., F.L.S., Trinity College, Cambridge *. 
(PrATE 18, and 9 Text-figures.) 
[Read 18th December, 1913. ] 
CONTENTS. 
Page 
Introdu+2tion............................. eat eeeeeecees 511 
Historical 2... ccc cece eee he 513 
The General Character and Biological Significance of the 
Inflorescence ................................ ...... 518 
The Solitary Terminal Flower and the origin from it of the 
simplest Inflorescence—The Dichasium .............. 521 
The Evolution of Racemose Inflorescences from the Pleio- 
chasium or Panicle ....... 2.0... cece cece ee eee eee 538 
Continuous Dichasia, Monochasia, and Sympodial Cymose 
Inflorescences ................................. h... 545 
The Origin of Solitary Axillary Flowers ...... eee tweens 548 
Intercalary and Pseudoterminal Inflorescences ....... eee. 556 
Summary ...................aarassrrsiisnsnsisissessasasasasassÀ 559 
I. INTRODUCTION. 
THE study of the Inflorescence from the evolutionary point of view has been 
strangely neglected. The treatment of this subject appears hardly as yet to 
have advanced beyond the limits of pure description. Botanical text-books 
have been and are still in the main content with a formal treatment of the 
Inflorescence. In these the various types of flower-groupings are at the outset 
sharply divided into the two classes, racemose and cymose ; then follow con- 
cise descriptions of the various kinds contained in the two categories. No 
attempt is made to connect racemose with cymose inflorescences, nor to trace 
the evolution of flower-clusters from some simple arrangement, as is to be 
found in the solitary terminal, or even in the single axillary flower. The 
account of the Inflorescence in one botanical text-book appears usually as a 
slavish copy of what occurs in an earlier work of a similar kind. The 
subject, in fact, is dealt with in a rather perfunctory fashion. 
* A brief exposition of most of the views expressed in this paper was given before the 
Botanical Section of the British Association at the Winnipeg Meeting (for Abstract see 
“ The Annual Report," 1909, p. 662). Since then the author has not seen reason to depart 
essentially from any of the views there given. 
LINN. JOURN.—BOTANY, VOL. XLII, IN 
