Wild Flowers as They Grow 



name rubm. They are further noteworthy for the 

 httle prickles that run up the midrib on the back 

 of the leaf and which do their humble share in fixing 

 the plant securely on the hedge-side. The face of 

 the leaf is smooth, the back is covered with a coating 

 of hairs. Kemer points out in a simple experiment 

 how these hairs affect the welfare of the plant. " If 

 one (i.e. a leaf) be wrapt round the bulb of a ther- 

 mometer — hairy side outwards, and another be wrapt 

 round the bulb of a second thermometer smooth 

 side outwards, and both thermometers placed in the 

 sun, the temperature of the leaf with the smooth 

 side outwards will be several degrees (2° — 5°) above 

 the temperature of the one with the hairy side 

 outwards. Also if such leaves be plucked and 

 exposed to the sun, some with the white felted side, 

 others with the smooth green side, uppermost, the 

 latter always shrivel and dry up much sooner than 

 the former. There can be no doubt after this, that 

 a dry coat of hair over succulent plant tissue which 



is exposed to the sun's rays, considerably restricts 



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