And according to another old adage we are told how:--

"When the aspen leaves are no bigger than your nail,
Is the time to look out for truff and peel."[7]

In short, it will be found that most of our counties have their items of
weather-lore; many of which, whilst varying in some respect, are
evidently modifications of one and the same belief. In many cases, too,
it must be admitted that this species of weather-wisdom is not based
altogether on idle fancy, but in accordance with recognised habits of
plants under certain conditions of weather. Indeed, it has been pointed
out that so sensitive are various flowers to any change in the
temperature or the amount of light, that it has been noticed that there
is as much as one hour's difference between the time when the same
flower opens at Paris and Upsala. It is, too, a familiar fact to
students of vegetable physiology that the leaves of _Porleria
hygrometrica_ fold down or rise up in accordance with the state of the
atmosphere. In short, it was pointed out in the _Standard_, in
illustration of the extreme sensitiveness of certain plants to
surrounding influences, how the _Haedysarums_ have been well known ever
since the days of Linnseus to suddenly begin to quiver without any
apparent cause, and just as suddenly to stop. Force cannot initiate the
movement, though cold will stop it, and heat will set in motion again
the suspended animation of the leaves. If artificially kept from moving
they will, when released, instantly begin their task anew and with
redoubled energy. Similarly the leaves of the _Colocasia esculenta_--the
tara of the Sandwich Islands--will often shiver at irregular times of
the day and night, and with such energy that little bells hung on the
petals tinkle. And yet, curious to say, we are told that the keenest eye
has not yet been able to detect any peculiarity in these plants to