189 



low ridges, are dominated by the black oaks and hickory. The sink- 

 holes of Randolph, Monroe, and Hardin counties support a mixture 

 similar to that of the better slopes. 



In many places the drier slopes and upper south slopes are 

 covered with post oak, mixed with blackjack, black oak, and pignut 

 hickory. Red cedar forms an understory of small trees with the post- 

 oak type of the ridges in Hardin County. The high ridges in the 

 western part of the region are sometimes covered with a scrubby 

 growth of black oak and black gum instead of the usual post-black- 

 blackjack mixture. 



The precipitous bluffs that are found in many places along the 

 Mississippi and Ohio rivers are often almost bare of vegetation of 

 any kind. Small red cedar is a common tree on such situations, 

 especially on limestone cliffs. It is often associated with black locust 

 and a scattering of other scrubby hardwoods. 



An interesting feature of this region is the occurrence of shortleaf 

 pine on the broken land along the bluffs of the Mississippi River in 

 Union County, beginning a little north of Wolf Lake and extending to 

 southern Jackson County. The trees are small, mostly from six to 

 fourteen inches in diameter, and grow on the stony upper slopes in 

 mixture with black and white oaks and other hardwoods. This is the 

 only place in the state, as far as known, where southern pine is 

 indigenous, although the same species is abundant and of economic 

 importance in parts of the Ozark Plateau of southern Missouri. 



The undergrowth characteristic of the hill lands is a mixture of 

 young trees, especially hickory and oak. with such shrubby species 

 as dogwood, sumach, witchhazel, and redbud. Blue beech and iron- 

 wood are common along drainage lines. 



The hill forests, like the bottomlands, have suffered from repeated 

 culling of the more valuable trees. The insect damage is much 

 greater. Practically all the more important species are attacked more 

 or less seriously, with the exception of the tulip. An insect which 

 is found in over ninety per cent of all young white oaks, causes con- 

 ■ siderable loss by injuring the quality of the wood while not seriously 

 affecting the growth. Frequently, young trees of nearly all species 

 are killed or badly deformed by insects during the first fifteen years 

 of growth. Those that suffer least during this period are maple, tulip, 

 and beech. 



It is a common practice to use woodland of this type for pasture, 

 and in some localities this has had an appreciable effect in keeping 

 down young growth. In the majority of cases, however, grazing has 

 not been heavy enough to seriously damage the stand. 



