PART IV. 
LECTURE XXXIX. 
THE FLOWERING SEASON OF PLANTS. 
Vernal, Summer, and Autumnal Flowers. 
From the first appearance of vegetation in the spring, until 
the commencement of winter, nature presents an ever varying 
scene. The phenomenon of the flowering of plants, is in many 
respects, similar to that of the putting forth of leaves ; in both, 
the same causes either hasten or retard this period. The put- 
ting forth of leaves, and the blossoming of flowers, differ how- 
ever in one circumstance ; the leaves begin by the upper leaf 
buds ; the flowers by the lower flower buds ; stipes, panicles, 
and thyrses begin to blossom gradually from the base to the 
summit. Cymes and umbels blossom from the outside to the 
centre. 
In plants of Ihe north, transported to the south, the period of 
the putting forth of leaves and blossoming is hastened ; in those 
of the south, carried to the north, it is retarded. Even in their 
native soil, this period varies in some degree in different seasons. 
With greater warmth of temperature, we have an earlier ap- 
pearance of vegetation ; yet in general, this variation is so 
slight, that botanists are able by observation, to fix with a suffi- 
cient degree of accuracy, the time of the flowering of plants in 
particular latitudes and climates. 
The progress of vegetation varying little from Latitude 40° to 
43° north, the remarks that we make on this subject, may apply 
to that region of country extending south to the mouth of the 
Hudson, north to the mouth of the Mohawk, eastward to the 
Atlantic, and westward to the Pacific Ocean. 
In Ohio, and the western part of New York, the climate, on 
account of the influence of the lakes, and the cold eastern winds 
from the Atlantic being broken by ranges of mountains, is mild- 
Changes in vegetation — Putting forth of leaves and blossoming of flow- 
ers agree in some respects, differ in others — Plants of the north transport- 
ed to the south, and tile reverse — Remarks on the progress of vegetation ; 
to what extent of country applying. 
