104 OUR NATIONAL PARKS 



kept on the surface by the pressure of the suc- 

 cessive layers of wood against the base. 



This admirable little tree grows on brushy, sun- 

 beaten slopes, which from their position and the 

 inflammable character of the vegetation are most 

 frequently fire-swept. These grounds it is able to 

 hold against all comers, however big and strong, 

 by saving its seeds until death, when all it has pro- 

 duced are scattered over the bare cleared ground, 

 and a new generation quickly springs out of the 

 ashes. Thus the curious fact that all the trees 

 of extensive groves and belts are of the same age 

 is accounted for, and their slender habit ; for 

 the lavish abundance of seed sown at the same 

 time makes a crowded growth, and the seedlings 

 with an even start rush up in a hurried race for 

 light and life. 



Only a few of the attenuata and Sabiniana 

 pines are within the boundaries of the park, the 

 former on the side of the Merced Canon, the 

 latter on the walls of Hetch-Hetchy Valley and 

 in the canon below it. 



The nut-pine (Pinus monophylla) is a small, 

 hardy, contented-looking tree, about fifteen or 

 twenty feet high and a foot in diameter. In its 

 youth the close radiating and aspiring branches 

 form a handsome broad-based pyramid, but when 

 fully grown it becomes round-topped, knotty, 

 and irregular, throwing out crooked divergent 

 limbs like an apple tree. The leaves are pale 



