﻿20 BULLETIN 24, U. S. DEPARTMENT OF AGEICULTUEE. 



MIXED HARDWOOD STANDS. 



Cottonwood grow T s in mixture either with willow or with other 

 hardwoods. It is more often found with the hardwoods on the better 

 drained glades and ridges throughout the bottom-land areas. The 

 mixture differs in the north and sfmth portions of the valley. The 

 predominating species associating with cottonwood in the upper 

 Mississippi Valley are silver maple, white elm, river birch, sycamore, 

 boxelder, and ash. Other species are butternut, shellbark hickory, 

 black walnut, pin oak, hackberry, and coffeetree. Most of these occur 

 also through much of the lower valley region, especially sycamore, 

 ash, hackberry, and boxelder. Several other species, however, which 

 are abundant in the South, become scarce or entirely disappear from 

 the composition as one proceeds north through the upper valley. 

 This is true particularly of red gum, tupelo, cypress, pecan, Avillow 

 oak, overcup oak, and cow oak. In addition to those already listed, 

 the following trees of minor value are often found with cottonwood 

 in either or both parts of the valley : Honey locust, black locust, 

 dogwood, mulberry, pawpaw, red elm, redbud, and hawthorn. Per- 

 haps the most characteristic associates of cottonwood in the north- 

 ern part of the valley are the silver maple and white elm, while 

 sycamore, hackberry, and red gum occur most abundantly with it in 

 the south. Nearly all of the associated species are present in the cen- 

 tral sections of the valley, including extensive bottomland areas 

 in Missouri, Arkansas, Illinois, Tennessee, and Kentucky. 



In certain parts of the bottoms, three classes of situations sup- 

 porting forest growth may be recognized, namely, the " glades," 

 the " ridges," and the " back sloughs." The sloughs remain under 

 water during the larger part of the growing season and their charac- 

 teristic forest growth is cypress and tupelo gum. Cottonwood prac- 

 tically never grows there. The bottoms subject to overflow for from 

 a few weeks to several months are sometimes spoken of collectively as 

 the " glades." These in turn may be irregularly divided by low- 

 " ridges," which are seldom over 6 feet in elevation, and often slope 

 almost imperceptibly to the level of the glades. The ridges and the 

 glades, however, are often not clearly defined, and even where they 

 are Avell marked the forest composition seems to be but little gov- 

 erned by them. Sycamore, pecan, shellbark hickory, and boxelder 

 are possibly more common on the better drained ridges. 



In mixed hardwood stands the cottonwood occurs in all propor- 

 tions from only one to two trees per acre up to nearly a pure stand. 

 Frequently cottonwood occurs in small groups on the lower depres- 

 sions. Such groups may have 10, 20, or more trees. At times the 

 cottonwood, either single trees or groups, seems to be restricted to 

 higher elevations, apparently because at the time of seeding the 



