48 BULLETIN 24, U. S. DEPARTMENT OF AGRICULTURE. 
PLANTING. 
ADVISABILITY. 
Wherever fully stocked stands can be secured by natural reproduc- 
tion no planting need be done. Where seed trees of cottonwood are 
wanting, on low-lying areas where water stands late in the spring, 
and on areas where young seedlings might be choked out by vines, 
briers, or low underbrush, it will be necessary to supplement natural 
reproduction with planting. Without planting, many portions of 
the logged-off areas would be only indifferently restocked, while in 
some places reproduction would be entirely lacking. 
Planting, however, is not limited to the restocking of cut-over 
bottom lands. A tree of such rapid growth and value as cottonwood 
will no doubt be introduced into localities where it is not now found 
naturally. The present local occurrence of cottonwood does not 
necessarily coincide with the areas where it might be expected to 
make good growth. The fact that this species is seldom found grow- 
ing naturally far from streams or moist bottom lands is the result of 
the failure of its seed to germinate satisfactorily on any but moist 
exposed mineral soils, such as are provided by the deposits from 
spring floods. This difficulty, however, is avoided by planting young 
trees. When the roots of the planted stock penetrate to a moist 
subsoil the tree displays its usual rapid development. 
Carolina poplar and Norway poplar are extensively advertised 
by nurserymen as superior to the common cottonwood for rapid 
growth in forest plantations. The three trees are all closely related. 
Differences in leaf and growth characteristics are often urged as 
grounds for considering Carolina poplar and cottonwood as distinct 
species. Carolina poplar itself, however, shows widely varying 
characteristics in different sections of the country, and often can not 
be distinguished from cottonwood. The differences between Norway 
poplar and cottonwood are equally vague. Both Norway and Caro- 
lina poplar are male trees propagated entirely from cuttings, and it 
is believed that both are derived from staminate trees of our com- 
mon cottonwood. It has already been pointed out that cottonwood 
has been commonly planted in Europe, where certain nurserymen 
claim to have developed exceptionally rapid growers. Possibly our 
Norway poplar may have originated in some such way, or it may 
have been taken originally from some of these rapid-growing Euro- 
pean forms. It is not at all certain, however, whether it really ex- 
ceeds our native cottonwood or the Carolina poplar in growth. Indi- 
cations are that in the north cuttings from thrifty Carolina or Nor- 
way poplar may develop more rapidly than cottonwood. In fact. 
it is generally believed that the male trees are more vigorous growers 
than the female. Another merit claimed for Norway poplar in com- 
