292 



HUTCHINSON'S POPULAR BOTANY 



FIG. 356. SENSITIVE PLANT (Mimosa pudica). 



Day position of leaf and leaflets. 



specimens of this plant not only assume an 

 almost vertical position, but by a singular 

 twisting of their blades, bring themselves 

 into a position which has earned it the name 

 of Compass-plant. The lobes of each pinnate- 

 parted leaf, extending like fingers on either 

 side of the midrib, are said to point due north 

 and south ; but some observers who have 

 watched the plant in its native habitat have 

 thrown considerable doubt upon the state- 

 ment, as they have found the leaves point- 

 ing in all directions. 



The leaves of the Marram (Psamma aren- 

 aria) exhibit a special structure in view of 

 this same purpose the prevention of ex- 

 cessive loss of water. The plant in ques- 

 tion is the Common Matweed of our sand- 

 hills, whose spreading fibrous roots are so 

 useful in binding together the shifting 

 sands on the coasts of Norfolk and Holland, 

 and in many other places. It has been noted 

 that " on wet days the leaves open longi- 

 tudinally, so that their inner surface is freely 

 exposed to the air, and the stomata which 

 are situated there may not have their func- 



is widely distributed 

 over the North Ameri- 

 can prairies : 



Look at this delicate plant 



that lifts its head from 



the meadow, 

 See how its leaves all point 



to the north, as true as 



the magnet ; 

 It is the Compass-flower, 



that the finger of God 



has suspended 

 Here on its fragile stalk, to 



direct the traveller's 



journey 

 Over the sea-like, pathless, 



limitless waste of the 



desert. 



The leaves of young 



FIG. 357. SENSITIVE PLANT. 

 At night, or when touched, the leaf hangs 

 down, and the leatlcts fold closely together. 



