INTRODUCTION. 
17 
corolla is closed after seven or eight in the 
morning. The common bindweed closes its 
flowers on the approach of rain ; hut the ana- 
gallis arvensis, or scarlet pimpernel,” which 
we often call shepherd’s weather-glass, “is 
the most sure in its indications, as the petals 
constantly close on the least humidity of at¬ 
mosphere. Barley is also singularly affected 
by the moisture or the dryness of the air. 
The awns are furnished with stiff points, all 
turning towards one end ; which extend when 
moist, and shorten when dry. The points, 
too, prevent their receding, so that they are 
drawn up or forward ; as moisture is return¬ 
ed, they advance, and so on; indeed, they may 
actually he said to travel forwards. The cap¬ 
sules of the geranium furnish admirable ba¬ 
rometers. Fasten the heard when fully ripe, 
upon a stand, and it will twist itself, or un¬ 
twist, according as the air is moist or dry. 
The flowers of the chick-weed, convolvulus, 
and oxalis, or wood sorrel, close their petals 
on the approach of rain. 
Gardens have been the delight of poets in 
all ages. All our poets have sung of flow- 
