46 The Ottawa Naturalist. [May 



RELATIONSHIP BETWEEN THE WEATHER AND 



PLANT GROWTH. 

 A Comparative Study of the Last Two Springs. 



By Cephas Guillet, 

 During the spring- of iqo2 and that of 1903 — that is to say 

 from the latter part of March to the latter part of June — I have 

 observed about 360 wild plants in bloom in and around Ottawa, 

 300 of which are natives. I have selected about half, or 170 (all 

 but 27 being natives), as being the most accurately observed dur- 

 ing both years as regards their first coming into bloom. For 

 purposes of accurate comparison I have divided each month into 

 periods of ten days, and shall call these periods the first, middle 

 and last periods of the month. When the month has thirty-one 

 days the last part contains eleven. 



Of the 170 plants, I find I observed 33 to come into bloom 

 on the same date each year, namely 9 in the middle and 8 in the 

 last part of April ; 5 in the first, 5 in the middle and one in the 

 last part of May ; and 4 in the first and one in the middle part of 

 June. It will be observed that the synchronous observations are 

 especially numerous in April, half occurring then, and become 

 less numerous as the season advances, there being only six during 

 the last part of May and the month of June If this were all the 

 evidence we had, we might surmise that the two seasons ran more 

 nearly parallel during the first half than during the last, which is 

 unusual. 



But the other observations establish this in a more exact and 

 satisfactory manner. Of the remaining 137 plants under discus- 

 sion only 39 bloomed earlier in 1902, while 98 bloomed earlier in 

 1903. And of the 39 which bloomed earlier in 1902, 31, or about 

 80 per cent of them, bloomed in March, April and the first part 

 of May, while of the 98 which bloomed earlier in 1903, only 11 

 bloomed in the corresponding period. The table given herewith 

 will make this plainer. It shows in a striking way that the sea- 

 son of 1903 overtook and passed that of 1902 before the middle 

 of May. 



