BAYBERRY FAMILY 51 
or very coarsely toothed, densely white-downy beneath. Cultivated 
as a shade tree and sometimes found growing spontaneously. 
2. P. tremuloides Michx. AMERICAN ASPEN, QUAKING Asp. A 
tree 20-60 ft. high, with greenish-white bark. Leaves roundish, 
heart-shaped, abruptly pointed, with small regular teeth. Leafstalk 
long, slender, and flattened at right angles to the broad surfaces of 
the leaf, causing it to sway edgewise with the least perceptible 
breeze. Common especially N. 
3. P. grandidentata Michx. @Larcre-Toornep Poprrar. A tree 
60-80 ft. high, with rather smooth gray bark. Leaves 3-5 in. long, 
roundish-ovate and irregularly sinuate-toothed; when young com- 
pletely covered with white silky wool, which is shed as soon as the 
leaf matures. The petiole is somewhat flattened, but not nearly as 
much so as that of the preceding species. Rich woods N. 
4. P. heterophylla L. Swamp Poprar. Branches only slightly 
angled. Leaves ovate, mostly obtuse at the apex, rounded or sub- 
cordate at the base, serrate with obtuse teeth, densely woolly when 
young, but becoming smooth with age; petioles cylindrical. Pistil- 
late catkins smooth, erect or spreading, loosely flowered. Capsule 
ovoid, usually shorter than the pedicel. Common in river swamps. 
A large tree with soft hght wood, which is often used in making 
cheap furniture.* 
. P. deltoides Marsh. Cortonwoop. A large and very rapidly 
growing tree, 75-100 ft. or more high, often with a markedly excur- 
rent trunk. Leaves large and broadly triangular, with crenate-serrate 
margins and long, tapering, acute tips: petioles long and considera- 
bly flattened. The numerous pediceled capsules are quite conspicu- 
ous when mature, and the air is filled with the downy seeds at the 
time when the capsules open. Common W., especially along streams, 
and planted as a shade tree. 
15. MYRICACEH. Baysperry FAamILy 
Shrubs with alternate, simple, resinous-dotted leaves ; monc- 
cious or dicecious. Flowers in short, bracted catkins ; perianth 
none. Staminate flowers 2-10, stamens hypogynous; pistillate 
flowers surrounded by 2-6 scales. Ovary 1-celled; style short; 
stigmas 2. 
I. MYRICA L. 
Shrubs or small trees with the branches clustered at the 
end of the growth of the previous season. Leaves  short- 
petioled, entire, lobed or toothed, the margin usually revolute, 
