I 1 2 
THE AMERICAN BOTANIST 
of fruits the ratio was as loo to 93. It is commonly observed, ol- 
ten to the great loss of the farmer, that seeds from plants brought 
into a northern country from the south produce plants whicli will 
not mature, for they are caught by the early frosts, while, vice 
versa, the northern plants in the south ripen far earlier than the 
native species. Thus it behooves the seeker after seed to stay as 
nearly as possible within his line of climatic latitude, or draw from 
a region slightly to the northward. 
It has been found that the average daily temperature in the 
shade must be above 39.2 degrees F., for sugar cane, and 46.4 de^ 
grees F., for potatoes, if one desires to observe the effects of ger- 
mination and growth. And the" higher the temperature the quick- 
er the germination and growth. Huberlandt found that with a 
temperature of 49.0 degrees it took beet seed twenty-two days to 
germinate, while with a temperature of 60.4 degrees only three 
and tliree-fourths days were necessary. With these plants, also, 
the maximum yields were secured by planting the ist of ]May 
. ather than the ist of INIarch or April. 
Rainfall is, next to temperature, the most important climatic 
element. The amount required for the growth of vegetation has 
been ascertained many times and for a large variety of plants, but 
with rainfall, as with temperature, there seems to be a wide range, 
possibly because plants adapt theinselves to their environment. In 
addition to the amotmt of rainfall required, it is essential also to 
know the frequency of fall, the rapidity of fall, and the average 
amount of each fall. Thus a rainfall of 4 to 5 inches per month 
would, if it came in showers of a half to three-quarters of an inch, 
provide ample moisture for the most thirsty farm crop, but if the 
same amount were dashed down in one or two heavy showers, the 
result would not be favorable. Other points of value are the pro- 
bability of rainfall, the length of time rain may reasonably be ex- 
pected to continue after it has set in, the extent of the country cov- 
ered, the temperature, humidity, sunshine and wind before and 
following the rain, the condition of the ground water, drainage, 
and composition of the soil, and the moisture characteristics of the 
plant. 
Sunshine as a factor in plant growth is probably third in im- 
