Botany. 257 
lected for observation, rather than the larger plants, and es- 
pecially trees. That such observations may be relied upon, 
the same plants should be observed, and the circumstances 
of place, soil, aspect, exposure to winds, &e. should be similar. 
All these aftect the ‘plant, and alter the time of flowering.—~ 
1 have known the common dandelion in blossom here on 
the 18th of March, though it does not usually flower till 
about five or six weeks later. Claytonia spatulata flowers 
some weeks earlier on a southern aspect, and where it is al- 
so protected from winds, than on a northern aspect, only a 
few rods from the former. The same is true of epigaea 
repens. 'Tussilago farfara blossoms some days earlier on the 
wild bank of a brook, than in the warm and rich soil of a 
garden. Chrysosplenium oppositifolium, shews its flow- 
ers ten days sooner in still waters, than beside brooks, 
where it is much less exposed to the sun. Also viola rotun- 
difolia. The above circumstances are so liable to be dif- 
ferent in different places, that the results cannot be very sat- 
isfactory when the smaller and annual plants are observed. 
There is another circumstance also, which increases this un- 
certainty, if the places be considerably remote. ‘There may 
be several days in the beginning of April, for stance, warm- 
er at one place than at another. As this would there bring 
forward the earliest plants sooner, a warmer climate would 
be indicated. But, should a few cooler days succeed, as Is 
usually the case, vegetation might be no earlier on the 
whole after a fortnight, than in those years in which the 
same plants first showed their blossoms several days. later. 
I have occasionally found a plant in biosscm | ~ about a 
month preceding the time given by Muhlenberg for its 
flawering in Pennsylvania. These facts prove, not that the 
flowering of plants does not indicate difference of climate, 
but that much accuracy of observation, for a series of years, 
is necessary, if those plants be selected for cbservation, 
which are easily affected by changes of temperature, as- 
pect, &c. in order to ascertain the climate or comparative 
mean temperature of different places. 
In respect to trees, the case is somewhat different. They 
are not so readily affected by changes of temperature. But 
the above mentioned circumstances of situation are seen ev- 
ery year to have considerable influence upon their time of 
flowering. The result of observations on trees will, how- 
