KEY TO THE SPECIES OF MAPLES 



1. Leaves pinnately compound with 3-7 leaflets; twigs stout, smooth, 



with encircling leaf scars A. negundo Boxelder, p. 307. 



1. Leaves simple, palmately lobed (rarely compound in Rocky Mountain 

 Maple). 



2. Leaves with closely, often doubly, toothed margins and sharp- 

 angled sinuses between lobes SOFT MAPLES. 



3. Winter buds bright green; leaves 4-7 inches across, 5-lobed, 

 bluntly toothed; fruit wings 1 H-2 inches long, diverging at 



right angle or less; Eurasian ornamental 



A. pseudoplatanus L., Sycamore Maple 



3. Winter buds red to brownish; native. 



4. Flowers appearing before the leaves from lateral, leafless 



buds; fruits maturing in late spring; buds with 4-8 visible 



scales; upper trunk bark smooth, light gray; eastern. 



5. Leaves very deeply 5-lobed, sides of middle lobe diverging, 



silvery-white beneath; fruit woolly when young, wings 



1 H-2 inches long, widely diverging; petals absent 



A. saccharinum Silver Maple, p. 299. 



5. Leaves 3-5 lobed, sides of middle lobe usually converging 

 toward apex, pale green beneath; fruit smooth, wings 



J^-1 inch long, slightly diverging; petals present 



A. rubrum Red Maple, p. 299. 



4. Flowers with petals, appearing with or after the leaves from 

 leaf buds; fruit maturing in late summer; 2 (rarely 4) \asible 

 bud scales. 



6. Leaves essentially glabrous; flowers in corymbs; western. 

 7. Leaves 7-9 lobed; fruit wings widely divergent; Pacific 



Coast A. circinatum Vine Maple, p. 301. 



7. Leaves 3-lobed (rarely 3-parted) ; fruit wings not di- 

 vergent; through west 



.4. glabrum Rocky Mountain Maple, p. 301. 



6. Leaves hairy beneath; flowers in racemes; eastern. 



8. Leaves coarsely toothed, 3-5 lobed; fruit wings }4 inch 

 long, diverging at about right angles; bark red-brown. . 

 .4. spicatum Mountain Maple, p. 303. 



8. Leaves finely doubly toothed, 3-lobed at apex; fruit 



wings ?i inch long, widely diverging; bark green with 



white stripes .4. pensijlvanicujji Striped Maple, p. 303. 



2. Leaf lobes entire or with few remote teeth, or slightly lobed; 



sinuses rounded between lobes; buds with several scales; flowers 



appearing with leaves HARD MAPLES. 



9. Petioles red with milky juice; fruit wings 1 ^^-2 inches long, 

 widely diverging; leaves 5-7 lobed, 5-7 inches across; natural- 

 ized Eurasian species .4. platanoides L., Norway Maple 



9. Petioles with watery juice; fruit wings usually diverging at right 

 angles or less; leaves 3-5 lobed; native. 

 10. Buds red, scales hairy on margins; western. 



11. Leaves 8-12 inches across 



.4. macrophyllum Bigleaf Maple, p. 305. 



11. Leaves 2-5 inches across 



A. grandidentatum Bigtooth Maple, p. 305. 



10. Buds brown; eastern. 



12. Leaves 1 H-3 inches across; bark smooth, pale; Virginia 

 to Missouri and south. 



13. Leaves pale and hairy beneath; fruit wings diverg- 

 ing at right angles 



A. barbaturn Michx., Florida Maple 



13. Leaves green and hairy beneath; fruit wings diverg- 

 ing at more than right angles 



A. leucoderme Small, Chalk Maple 



12. Leaves 3-6 inches across; bark rough and dark; eastern 

 North America. 



14. Twigs red-brown; leaves 5-lobed, glabrous beneath 

 A. saccharum Sugar Maple, p. 297. 



14. Twigs orange; leaves mostly 3-lobed, usually hairy 

 beneath .4. nigrum Black Maple, p. 297. 



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