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. FLOWEKS WITHOUT A COROLLA, OFTEN 

 ALSO WITHOUT A CALYX. 



SAUCACE.ffi;, WILLOW FAjMILY. 



Dioecious 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.) 



POPTJLUS, POPLAT!, 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 AsPEX, QuAKIXG AsP. 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. 



6. (P. grandidentata), Large-toothed Poplar. A tree 60 

 to 80 ft. high, with rather smooth gray bark ; leaves 3-5 in. long. 



