THE FLORAL STEM. 737 



stem. The flower-stalk may originate from all three regions of the stem. In-many 

 parasites and saprophytes without chlorophyll it arises from the axil of a scale-leaf; 

 in many annual plants, e.g. the Pimpernel and the Ivy-leaved Speedwell (Anagallis 

 arvensis and Veronica hederifolia), it springs from the axil of a green foliage-leaf; 

 more frequently, however, it is developed in the axil of a so-called bract, which is 

 to be regarded as a floral-leaf. 



The flowers are seldom isolated; in most instances they are associated in clusters, 

 each cluster being termed an inflorescence (inflorescentia). For descriptive purposes 

 it was found necessary to apply short names to the different inflorescences, and a 

 special terminology was created by the older botanists which was most excellent, 

 but which in modern times has become very cumbrous owing to the introduction 

 and substitution of. a host of Greek names which sound very learned, but are quite 

 superfluous. It does not lie within the scope of this book to follow this terminology 

 in detail. It is enough to bring forward the most prominent forms of inflorescence. 

 I shall also touch as shortly as possible on the significance of these various associa- 

 tions and groups of flowers to the life of the plant, since this subject will be fully 

 discussed in the second volume when describing the processes of fertilization, and 

 especially the crossing of neighbouring flowers. 



In describing inflorescences we shall frequently make use of the words " main 

 axis " and " lateral axis ", and in order to prevent misapprehension, it is as well to 

 point out here that the main axis of the inflorescence, i.e. that part of the stem 

 from which the flower-stalks branch off, is only in rare cases the direct continuation 

 of the stem which proceeds from the bud of the hypocotyl (i.e. the real main 

 axis of the whole plant). Even in the Hyacinth the green scape which rises from 

 the ground, and branches off into a wealth of flower- stalks in its upper part, is 

 not the original main axis, but a side axis springing from the axil of a bulb- 

 scale. We are accustomed, however, to call that stem the main one which takes 

 the lead in a certain region of the plant, forming buds which become lateral shoots 

 in the axils of its leaves. The term "main axis" is therefore only relative; with 

 respect to its lateral shoots it is a main axis, but with regard to the stem from 

 which it originates, it itself must be looked upon as a lateral axis. In order to 

 simplify the account and to shorten the descriptions of inflorescences, it is better 

 to call the main axis round which the individual flower-stalks are grouped as 

 round a common centre, or which has conspicuously taken the lead in the whole 

 system of axes the " rachis ". 



Inflorescences have been classified into two groups, the centrifugal and centri- 

 petal. In centrifugal inflorescences the rachis terminates with a flower, but is 

 retarded in growth and is outstripped by two, more rarely by three, lateral axes 

 springing from the rachis below the first-formed flower-bud just mentioned. 

 Secondary lateral axes may again spring from each of these lateral shoots, and 

 their relative main axes may be again overtopped in the manner described. The 

 flower-bud by which the rachis is terminated always opens first; then the flower- 

 buds on the first series of lateral axes, then those on the second series of lateral 

 VOL. I. 



