ANGIOSPERMS. 595 



leaves; frequently coloured {i.e, not green) or altogether colourless. They are dis- 

 tinguished as Hypsophyllary Leaves or Bracts; and in this term are frequently included 

 the small leaves which spring Irom the pedicels and which often have no axillary shoots 

 {Bracteoles). Leaves of this kind are sometimes entirely absent from the inflorescence 

 or from certain parts of it ; the ultimate floral axes or pedicels of the flowers are then 

 not axillary, as in Aroideae, Gruciferae, &c. 



A large number of different forms of inflorescence may arise by the combination 

 in different ways of the determining characters already mentioned. Each form is 

 constant in the same species, and is often characteristic of a whole genus or family ; 

 hence the form of the inflorescence often not only determines the habit of the plant, 

 but is also of value to its systematic classification. 



The most convenient basis for the classification of the forms of inflorescence is the 

 mode of branching. This is less variable than the other features, and can be referred 

 to a few types ; it also affords distinctive characters for the principal groups, which 

 might then be further sub-divided according to the length and thickness of the separate 

 axes and other points. 



With reference to the mode of branching, the first point to observe is that every 

 inflorescence originates from the normal terminal branching of a growing axis ; the 

 mode of branching is always monopodia! in Angiosperms with the exception of the cases 

 mentioned under Division 14; i.e. the branches arise laterally beneath the apex of 

 the growing mother-shoot. If the leaves on this shoot (the bracts) are conspicuously 

 developed, the lateral axes arise in their axils ; if they are inconspicuous or abortive, the 

 lateral axes of the inflorescence are not indeed axillary, but their mode of branching and 

 growth remain the same as if the bracts were present ; and it is usual, in framing the 

 divisions, not to lay great stress on this circumstance (see p. 176). But the presence of 

 bracts is of great practical value, since it assists in the recognition of the true mode of 

 branching even in the mature inflorescence, inasmuch as the axillary shoot is always 

 lateral. When the bracts are absent it is often difficult to distinguish a lateral 

 from a primary axis, since the former often grows as vigorously as the latter, or even 

 more so. In Section 24 of the chapter on General Morphology (p. 169 et seq.) the 

 principles have been laid down according to which the various systems of branching 

 may be generally classified ; these will serve also in every respect for inflorescences, 

 and form the basis of the characters of the larger groups in the following classifica- 

 tion. Of the great number of separate forms of inflorescence only the more common 

 ones, a nomenclature for which is already provided in systematic botany, will be 

 enumerated ^ 



A. Racemose (monopodial). Centripetal, or Indefinite Inflorescences, in the 



widest sense of the terms, result from the primary axis or rachis of the branching system 

 producing a larger or smaller number of lateral shoots in acropetal succession; the 

 capacity for development of each lateral shoot being smaller, or at least not greater, 

 than that of the portion of the primary axis which lies above it. 



a. Spicate hiflorescences arise when the lateral axes of the first order do not branch 

 and are all floral axes ; the rachis terminates with or without a flower, 

 (a) Spicate Inflorescences with elongated rachis : — 



1. The Spike: Flowers sessile; rachis slender (as in some Grasses). 



2. TheSpadix: Flowers sessile ; rachis thick and fleshy, usually enveloped 



in a large spathe ; bracts generally undeveloped (Aroideae). 



3. The Raceme: Flowers distinctly stalked {e.g. Gruciferae, without bracts ; 



Berberis, Menyanthes^ Campanula^ rachis terminating in a flower). 



^ Compare the dissimilar descriptions in Ascherson's Flora of the Province Brandenburg, 

 Berlin, 1864, and in Hofmeister's Allgemeine Morphologie, § 7. 



Q q 2 



