﻿COTTONWOOD IN THE MISSISSIPPI VALLEY. 11 



of the Mississippi River into the (Treat Plains region, where it is 

 found at altitudes as high as 9,000 feet, but is confined to the river 

 banks. 



BOTANICAL CHARACTERISTICS. 



Populus deltoides Marsh is usually known merely as cottonwood, 

 but in certain sections is variously -spoken of as Carolina poplar, 

 yellow cottonwood, white cottonwood, big cottonwood, cotton tree, 

 broadleaved cottonwood, Vermont poplar, necklace poplar, and still 

 other local names. It has been introduced into Europe, where it is 

 variously termed the Swiss white poplar, the black Italian poplar, 

 the Canadian poplar, etc. 



The leaves, which are usually from 3 to G inches long and equally 

 board, are more or less triangular in shape, sharply pointed, 

 prominently veined, and edged with glandular incurved teeth. 

 The leaves on the more vigorous shoots in the top of the tree 

 are frequently more than twice the length of the others. When 

 crushed they emit a pleasant balsamic odor. The leafstalks are 

 flattened on the sides for most .of their length, but become more 

 round near their junction with the twig. Cottonwood has long, 

 pointed, greenish or reddish-green winter buds, which are very res- 

 inous and are somewhat flattened. The bark on the younger stems 

 and branches is comparatively thin and of a light grayish-yellow 

 color, tinged with green, but on the trunks of older trees becomes 

 rough, thick, and deeply furrowed and is dark grayish in color. 



In cottonwood the male and female flowers are borne on different 

 trees (dioecious). Seed therefore is borne only on female individuals, 

 whereas the male trees are always barren. The flowers bloom from 

 February to April, according to the latitude, and always before the 

 leaves are out. They occur in long pendulous catkins. The female 

 catkins mature toward the last of April or May, even before the 

 leaves have attained full growth, at which time the 3 or 4 valved 

 capsules open and shed large quantities of " cottony " seed that is 

 carried far and wide by the wind. To this abundant production of 

 downy-coated seed cottonwood owes its name as well as the disfavor 

 in which it is sometimes held for lawn and street planting. It is 

 a very simple matter, however, to overcome this objection by propa- 

 gating only male trees. (Se'e fig. 1.) 



Populus deltoides is easily distinguished from the swamp cotton- 

 wood {Populus heterophylla Linn.), which has somewhat the same 

 range, by its distinctly triangular-shaped leaves and its thicker, more 

 closely attached bark.. In the western extension of its range cotton- 

 wood grows with norrow-leaved cottonwood (P. angustifolia James) , 

 wliich is readily disinguished by its narrow lanceolate leaves. 



