CHAPTER III. 
FORMS OF VEGETATION, GEOGRAPHICAL 
DISTRIBUTION OF PLANTS, &c. 
In dealing with general morphology we have seen that 
the reproductive organs are subject to modification chiefly 
in accordance with the necessities of the pollination 
processes. The vegetative organs on the other hand are 
intimately related in their structural and other features to 
the conditions of climate and habitat under which they 
exist, and in comparing plants from different regions we 
often find great dissimilarity of the vegetative together with 
great similarity of the reproductive systems. It is with this 
side of the subject that we have now to deal, considering 
the vegetation of different regions and habitats both from 
the morphological and physiological points of view; we shall 
thus endeavour to gain an insight at the same time into the 
subjects of morphology, natural history, and geographical 
distribution of plants. Thus the various forms of stems 
usually described together in morphological works as modi- 
fied stems will be found treated here, but their structure is 
dealt with in connection with their functions, so as to 
emphasise the important fact that modification of the 
former accompanies modification of the latter. 
Geographical Distribution of Plants, or Geo- 
graphical Botany 1 , deals with problems connected with 
1 A. de Candolle, Geographie botanique raisonnee , 1855 > 
J. D. Hooker, Flora of Australia (Introductory Essay to Flora of 
Tasmania, in Botany of Antarctic Exp., 1859), Introductory Essay to 
Flora of New Zealand , 1st Ed., 1853; Grisebach, Die Vegetation der 
Erde , 1872 ; Drude, Handbuch der Pflanzengeographie, 1890 (or French 
translation by Poirault), Atlas der Pflanzenverbreitung ; Warming, 
Oekologische Pflanzengeographie (German by Knoblauch), Schimper, 
Pflanzengeographie auf physiologiscker Grundlage, 1898; Darwin, 
Origin of Species, & c. ; Koppen, Versuch einer Klassifikation d. Klunate . 
Geog. Zeitschr. Leipzig, 1901. 
