GROWTH-FORMS OF FLORA OF NEW YORK AND VICINITY 25 
Helophytes and Hydrophytes. The former has buds at the bottom 
of the water. They are mostly marsh species such as Typha, Spar- 
ganium, Acorus, etc. Hydrophytes have perennating rhizomes or 
winter-buds and are truly aquatic, such as Castalia, Elodea and 
Potamogeton. 
Therophytes. Annuals. 
A tabular view of these different growth forms, with the abbrevi- 
ations as used in this paper follows : 
MG = Megaphanerophytes CH = Chamaephytes 
MS = Mesaphanerophytes H = Hemicryptophytes 
MC = Microphanerophytes G = Geophytes 
N = Nanophanerophytes HH = Helophytes and Hydrophytes 
T = Therophytes 
Raunkiaer's method of adapting the study of these growth-forms 
as related to temperature is to estimate the number of species char- 
acterized by these different forms, and to get the percentages of the 
different growth-forms in the flora. For the purpose of comparison 
he established a "normal spectrum" which is constructed on purely 
hypothetical lines. It consists of 400 species carefully chosen from 
1,000 representative species. The analysis of these 400 species into 
their different growth-forms gives, theoretically, the ideal phyto- 
climatic spectrum of the whole earth. According to Raunkiaer the 
percentage of species belonging to each growth-form, in the ideal 
spectrum of 400 species, is as follows: 
Percentage of growth-forms in normal spectrum^ 
Type of growth-form MG & MS MC N CH H G HH T 
Percentage of growth-forms 6 17 20 9 27 3 i 13 
These percentages are supposed to reflect the average condition 
as to the growth-forms of the whole earth. Of course they may need 
future revision; it would be strange if they did not as our knowledge 
of the habits of various species increases. 
The method of comparing the climate of different parts of the 
earth's surface, on this conception, involves working out the per- 
centages of the different growth-forms exhibited in the areas and a 
^ I have omitted epiphytes and stem-succulents, as being two of Raunkiaer's 
groups hardly applicable to our area. 
