glandular hairs, spinous emergences, wing-like shading laminae — all as mechanisms 

 capable of subsequent utilization, more or less successfuU}-, in the dispersal of fruits 

 and seeds. Minor examples of such phenomena in trees of Northern latitudes illus- 

 trate the fact that all such adaptations were originally attained during the rigorous 

 selection imjilied in solving the problems of tropical vegetation. 



Forest Trees, taken as plants with perennial woody habit, ranging from small 

 shrubs and climbers to massive timber-trees of high forest, are scheduled at 4,400 

 species (Brandis, 1911), those giving appreciable limber at 1,450 (Gamble, 1902), as 

 economically significant to tlie forester, 300 (Troup, 19 13), and at least 200 may be 

 regarded as generally important. 



Systematy : For purposes of cataloguing and ready reference, plants are classi- 

 fied in groups and sections (phyla), to families, genera, and species, the main outlines 

 of which are still more or less empirical and largely traditional, though aiming at 

 a 'Natural System'; i. e., one expressing genetic relationship. The recognition of 

 even a ' sjjecies ' is still arbitrary, and all classification may be regarded as provisional. 

 The morphological organization of the flower, fruit, and seed, as including the com- 

 plex processes of racial mfchanism of reproduction, is generally utilized ; since this 

 covers the elaborate provision for the specialization of the floral shoot-system and its 

 mechanism, as concerned with: — (i) the essential process of cross-pollination, or the 

 approximation of the microspores to the vicinity of the megasporangium of the sporo- 

 phyte-phase ; (2) the elaboration of the ovary-chamber as the special feature of the 

 Angiosperm ; (3) the mechanism of seed and fruit-formation as allotted to post- 

 sexual nutrition and the care of the embryo ; and (4) the structures associated with the 

 dispersal, perennation, and germination of the seed. So complex and inter-related 

 are the adaptations for these several functions, taken singly or in combination, that 

 the somatic organization of the general vegetative and arboreal growth, its morpho- 

 logy and relation to insolation and desiccation, as expressing the more immediate 

 relation of the individual to its present environment, become of relatively subsidiary 

 importance. Such data may be still significant in lesser degree ; since though they 

 are equally the ecological inheritance of past ages, they appear on the whole less con- 

 servative in obscure mechanism, through which may be traced older factors in the 

 evolution of flowering and seed-plants of more remote epochs. 



Systems of Classification, though now admittedly aiming at phyletic presenta- 

 tion, are not to be criticized too strictly in this direction. A ' System ' is the official 

 presentation of the subject at any given time, with which the individual botanist has 

 little to do. Cataloguing and bookkeeping have to be maintained as a common 

 standard of reference. The limitations of species, genera, and families are comrnonly 

 accepted, though subject to minor sources of error ; these become the units of 

 systematy. Official systems only differ as they reflect more modern outlooks for 

 regarding the grouping and terminology of the larger sections. The arrangement of 

 the latter in any linear sequence for book-presentation is largely a matter of con- 

 venience and convention. 



Natural Classification aims at the arrangement which may most clearly visualize 

 the phyletic progression of different races ; but the life of every higher plant involves 

 the balanced compromise in the solution of quite a number of distinct problems, each 

 requiring a set of complex specialized mechanism, adapted from the remains of past 

 mechanisms of older phases of existence. Hence every race, genus, and species may 

 show independently combined lines of evolutionary progression, or even of deteriora- 

 tion, in many different directions differently, or at unequal rates. No very primitive 

 or archaic plant can be now in existence : all may be highly organized in different 

 respects, or present different horizons of attainment in the same category. All systematy 

 thus ends in being artificial to some extent, and convenience is more important than 

 pedantic discussion ; after all, systematy is made for the advance of scientific botany, 

 not vice versa, and classification can no longer be regarded as an end in itself. 



The Modern System, based on the Natural System of Jussieu (1789), extended 



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