24 NORMAN TAYLOR 



not as such, but as it is reflected in the vegetation which we all know 

 it to have controlled. Such a method is not at all in line with older 

 studies, it is really an ex post facto method of determining climate 

 by the character of the vegetative response. From the standpoint 

 of the ecologist and plant geographer, what could be more logical 

 and reasonable? Temperature factors are not what one makes them 

 out to be with an elaborate instrumental or mathematical method; 

 they are rather what one finds them as reflected in the vegetation 

 itself. Of course, in order to get the quality and kind of this implied 

 vegetative response, we must study plants in a slightly new light, 

 and Raunkiaer has devised, after Warming and a few earlier writers, 

 a scheme for such a study. 



His theory is that plants react to climate by the kind and amount 

 of protection exhibited by the perennating growth points during the 

 winter or critical season. Upon this assumption he divides all vegeta- 

 tion into several different groups of growth-forms sometimes called 

 life-forms, depending on the kind and amount of protection to their 

 growing buds exhibited by each. In the following account, I have 

 included only those of his growth-forms that are found in eastern 

 North America, which may be characterized as follows: 



Phanerophytes. Woody plants of all types, both evergreen and 

 deciduous and exhibiting the least amount of protection from the 

 cold, as showing the greatest amount of exposure. The group may 

 be divided into Megaphanerophytes, trees over 30 m.; Mesaphan- 

 erophytes, trees 8-30 m. ; Microphanerophytes, shrubs or trees 2-8 m. ; 

 Nanophanerophytes. shrubs under 2 m. Examples of all these are 

 too common to need citing. 



Chamaephytes. Perennial by virtue of the fact that the buds are 

 just above the ground, or on the surface, and are thus often protected 

 by the snow blanket. Among local species Arctostaphylos Uva-Ursi, 

 Epigaea, Convolvulus, etc., are good examples. It includes, also, 

 cushion-plants. 



Hemicryptophytes. With dormant buds in the upper crust of 

 the soil, the top of the plant dying down in the winter. Common 

 examples suggest themselves, as all our shallow-rooted herbaceous 

 perennials belong here. 



Geophytes. Perennial by bulbs, rhizomes, tubers or by root- 

 buds. Examples among our native plants: most Orchidaceae, Lili- 

 aceae, Sanguinaria, Hydrastis, etc. 



