THE STEM OF PLANTS. 31 
An acquaintance with the ligneous stems of forest trees is inter- 
esting in more than one respect. Nature has collected all her 
powers to give to trees the strength necessary to resist the dangers 
and the causes of destruction which threaten them. Their wide- 
Fig. 31.—Subterr tem of Carex, with shoots for four years. 
spread and bushy summits, the immense mass of foliage which 
they support, and the great height to which they attain at the end 
of their growth, expose them to the fury of tempests. Their 
trunks must be immovably solid, in order to brave all the violence 
