CHAP. II GROWTH-FORMS 5 



remarked that these did not take sufficient note of geographical con- 

 siderations. 



Reiter, in 1885, was the next to devote detailed consideration to the 

 subject. His standpoint was sound and he laid stress upon internal 

 structure, particular obser\'ation of truly adaptive features, and a due 

 regard for all the types of a characteristic mode of life and of special 

 design as opposed to a regard for merely such of these types as occur 

 in great numbers. Nevertheless Reiter's ' system ' is capable of im- 

 provements. 



Subsequently Drude ^ dealt with the question. He adopted the 

 ' biological-geographical ' standpoint as resting on the answers to the 

 two questions : 



What functional role does any particular species of plant play in 

 the vegetation of a definite country ? 



How does it complete the whole of its periodic life-cycle under the 

 conditions prevailing in its habitat ? 



As features of the greater importance he denoted, ' the duration of 

 organs and the protective measures against injuries during the resting 

 period,' also ' the position of the renewal-shoot on the main axis in 

 relation to hibernation '.^ In his later work he divided plants into 

 thirty-five classes of vegetative forms. 



Krause,^ and later Pound and Clements,* gave the main outlines of 

 systems. That of Pound and Clements approaches, as a whole, Drude's. 

 It ranges plants in the following main groups : Woody plants, half- 

 shrubs, pleiocyclic herbs, hapaxanthic herbs, water-plants, hystero- 

 phytes, and thallophytes, and it contains thirty-four sub-groups. 



Raunkiar ^ devised a system, in which, like Drude, he laid greatest 

 stress upon the adaptation of plants to enable them to five through 

 the unfavourable seasons, as particularly evinced by the degree and 

 kind of protection afforded to the dormant buds and shoot-apices. His 

 five chief groups were phanerophytes, chamaephytes, hemicryptophytes, 

 cryptophytes, and therophytes. 



The most recent treatment of this subject is due to Warming, who, 

 since 1890, has published various papers dealing with the structure of 

 growth-forms and the parts they play in formations. In 1908 ^ he 

 attempted to map out the main lines of a system of w'hich the following 

 is an outhne : 



Just as species are the units in systematic botany, so are growth- 

 forms the units in oecological botany. It is therefore of some practical 

 importance to test the possibility of founding and naming a limited 

 number of growth-forms upon true oecological principles. It cannot 

 be sufficiently insisted that the greatest advance, not only in biology 

 in its wider sense, but also in oecological phyto-geography, will be the 

 oecological interpretation of the various growth-forms : from this ulti- 

 mate goal we are yet far distant. 



It is an intricate task to arrange the growth-forms of plants in a 

 genetic system, because they exhibit an overwhelming diversity of forms 



' Drude, 1887, 1889, 1890, 1896. ^ Drude, 1890. p. 69 ; 1896, p. 46". 



' Krause, 1891. * Pound and Clements, 1898. 



' Raunkiar, 1903, 1905, 1907. * Warming, 1908. 



