XI 
PLANTS THAT TELL THE TIME OF DAY; PLANTS THAT 
KEEP A DIARY 
LANTS can actually tell the time! 
Certain plants open and close at definite 
hours of the day with such regularity that they 
can be, and have been, relied upon as timepieces. 
Unknowing persons have claimed that this is “due 
to the changes in temperature,” but there is evident 
in plant life an understanding of periods of time 
which can be laid to no such cause as temperature. 
Weare forced to believe that they have a knowledge 
of the hours of the day. There are some plants 
—the white or red water-lily, the proliferous pink, 
and the purple sandwort—which regularly open 
and close not only at definite hours but at definite 
minutes in those hours! 
The idea of plants telling the time of day is not 
new. The Swedish botanist, Linnzus, realising 
this remarkable power of the plant, built himself a 
floral clock which should, by the hours and minutes 
of the opening and closing of his plants, indicate 
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