682 



TREES OF NORTH AMERICA 



Flowers without petals; sepals united; inflorescence corymbose; pedicels long, pen- 

 dulous, mostly hairy. 

 Leaves pale or glaucescent, or green and glabrous beneath. 



Leaves green or pale beneath, glabrous or in one form villose-pubescent on the 



under side of the veins and on the petioles. C. A. saccharum (A, C). 



Leaves pale and pubescent, rarely glabrous beneath, their lobes usually short 



and obtuse or acuminate. 



Lobes of the leaves only slightly lobed or entire; bark of young trees smooth 



and pale. 7. A. floridanum (C). 



Lobes of the leaves distinctly lobulate; bark of young trees dark brown and 



scaly. H. A. grandidentatum (F, H). 



Leaves green and pubescent, rarely glabrous beneath. 



Leaves hirsute-pubescent beneath and on the petioles, the lobes entire or lobu- 

 late, the basal sinus often closed by the lower lobes; bark dark and furrowed. 



9. A. nigrum (A). 



Leaves pilose-pubescent, rarely glabrous beneath, the lobes slightly lobulate, 

 the basal sinus open; petioles glabrous; bark pale and smooth. 



10. A. leucoderme (C). 

 Flowers appearing before the leaves in dense lateral clusters from separate buds; 



leaves 5-lobed (3-lobed in varieties of 12) \ fruit ripening in May or June. 

 Flowers sessile or short-stalked, without petals; ovary and young fruit tomentose. 



11. A. saccharinum. 

 Flowers on long pedicels, with petals; ovary and young fruit glabrous. 



12. A. rubrum. 

 Leaves 3-7-foliolate; flowers dioecious, without petals. 13. A. Negundo (A, B, C, F, G, H) . 



1. Acer glabrum Torr. Dwarf Maple. 



Leaves glabrous, thin, rounded in outline, cordate-truncate or cuneate at base, 3-5-lobed, 

 the middle lobe usually narrowed and entire below the middle, or often 3-parted or 3-foli- 

 olate (f. trisecta Sarg.), with acute or obtuse doubly serrate lobes, 3'-5' in diameter, dark 



Fig. 614 



green and lustrous on the upper, paler on the lower surface, with conspicuous veinlets; 

 petioles stout, grooved, l'-6' in length, and often bright red. Flowers about ' long on 

 short slender pedicels, in loose few-flowered glabrous racemose corymbs on slender droop- 

 ing peduncles from the end of 2-leaved branchlets, the staminate and pistillate usually 

 produced separately on different plants; sepals oblong, obtuse, petaloid, as long as the 



