DICOTYLEDONOUS PLANTS. 17 
SUB-CLASS II.— DICOTYLEDONOUS PLANTS. 
Stems composed of bark, wood, and pith; in woody stems 
which live over from year to year, the wood generally in 
annual rings, traversed at right angles by medullary rays. 
Leaves netted-veined. Parts of the flower usually in fours 
or fives. Cotyledons 2 (rarely none). 
Division I. 
APETALOUS PLANTS. FLOWERS WITHOUT A COROLLA, OFTEN 
ALSO WITHOUT A CALYX. 
SALICACEZ, WILLOW FAMILY. 
Diecious trees or shrubs, with flowers in catkins (Figs. 
108, 121), destitute of floral envelopes; fruit a 1-celled pod, 
with numerous seeds, provided with rather long and silky 
down, by means of which they are transported by the wind. 
(Although the willow genus is easy to recognize, it is very 
hard to identify most of the species; many experienced 
botanists cannot do it.) 
POPULUS, POPLAR, ASPEN. 
Flowers borne in long, drooping catkins, which appear be- 
fore the leaves; scales of the catkins irregularly cut toward 
the tip. Stamens 8-30 or more. Stigmas 2-4. Capsules 
opening early by 2 or 4 valves. : 
a. (P. TREMULOIDES), AMERICAN ASPEN, QUAKING AspP. A 
tree 20 to 60 ft. high, with greenish-white bark ; leaves roundish 
heart-shaped, abruptly pointed, with small regular teeth. Leaf-stalk 
long, slender, and flattened at right angles to the broad surfaces of 
the leaf, causing it to sway edgewise with the least perceptible 
breeze. 
b. (P. GRANDIDENTATA), LARGE-TOOTHED Popiar. A tree 60 
~ 
u 
. 
to 80 ft. high, with rather smooth gray bark; leaves 3-5 in. long, 
