[Reprinted from the American Journal of Botany, 2: 32-70, January, 1915] 



THE GROWTH-FORMS OF THE FLORA OF NEW YORK 



AND VICINITY 1 



Norman Taylor 



There has recently appeared in a work on the flora of New York, 2 

 an account of the relation between climate and the vegetation in 

 which the length of the growing season was used as the chief tem- 

 perature factor. This was done for the reason that it seemed to 

 account for the distribution of the flora more closely than any other 

 ascertainable temperature factor. While it is difficult to conceive of 

 any climatic agency, such as the number of frostless days, the maxi- 

 mum or minimum temperatures, or the accumulated heat units, as 

 actually controlling the distribution of the flora, yet it is a matter of 

 common observation that temperature does affect vegetation and its 

 distribution. How, then, are we to measure the effect of climate, 

 and particularly temperature, on plant life? All of the older methods, 

 including the one used in the flora of the vicinity of New York, 

 have studied climate as a rather distinct entity, and then imposed a 

 somewhat rigid, usually instrumentally correct scheme, on a com- 

 plex aggregate like a local flora. All such schemes require con- 

 siderable wrenching of the purely climatic factors on the one hand, 

 as they certainly do of the assumed vegetative response on the other. 

 Until recently, and with the possible exception of Merriam's "Life 

 Zones," all studies of the effect of temperature on plants were of this 

 type. They were essentially attempts to explain the facts of plant 

 distribution by measured temperatures or heat units or frostless days 

 or by some combination of these methods. 



Raunkiaer 3 has studied temperature factors from an entirely 

 different viewpoint. His idea, briefly, is that we must study climate, 



1 Brooklyn Botanic Garden Contributions, No. 9. 



2 Taylor, N. Flora of the vicinity of New York: A contribution to plant 

 geography. Mem. N. Y. Bot. Garden 5: 1-683. I 9 I 5- See pp. 33-36. All the 

 statistics and figures used in this paper may be verified in that book. The nomen- 

 clature of the present paper is essentially that of the Gray's Manual. 



3 A fairly complete account of Raunkiaer's system, with a bibliography, may 

 be found in Journ. Ecol. 1: 16-26. 1913. 



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