The Maples 



639 



Inflorescence erect; petals linear to linear-spatulate, 2 or 3 



times as long as the sepals; small tree or shrub. 

 Inflorescence drooping; petals oblong to obovate, about as 

 long as the sepals. 

 Ovary and fruit glabrous; leaves 3-lobed toward the apex; 



small eastern tree. 

 Ovary and fruit hirsute; leaves deeply 5-lobed; large western 

 tree. 

 ** Flowers corymbose or short-racemose; western trees and shrubs. 

 Petals much shorter than the purple sepals. 

 Petals about as long as the sepals. 

 Samaras diverging at 180 degrees. 

 Samaras ascending or erect. 

 Terminal leaf-lobe rhombic. 

 Terminal leaf-lobe ovate, 

 b. Flowers in lateral umbel-like clusters, expanding with the leaves or 

 before them. 

 Flowers expanding before the leaves, their pedicels not drooping. 

 Petals obsolete or none; calyx 5 -toothed; ovary pubescent. 

 Petals present; sepals nearly distinct; ovary glabrous. 

 Leaves nearly glabrous beneath, or somewhat pubescent; 

 samaras less than 4 cm. long. 

 Leaves bright green above, pale green or whitish beneath. 

 Wing of the samara broadened above the middle. 

 Wing of the samara linear, scarcely widened above. 

 Leaves dark green above, pale beneath, mostly 3-lobed. 

 Leaves persistently woolly beneath, at least along the veins; 

 samaras mostly 4 cm. long or longer. 

 Flowers expanding with the leaves, their pedicels drooping. 

 Eastern trees; leaves large. 



Bark of trunk gray to black; samaras mostly 3 cm. long or 

 longer. 

 Leaves pale or glaucous beneath, not stipulate, their 



lobes coarsely toothed. 

 Leaves green on both sides, often stipulate, their lobes 

 entire or undulate. 

 Bark white; samaras mostly less than 3 cm. long. 



Leaves glaucous and sometimes pale-pubescent beneath; 



samaras green. 

 Leaves green and velvety beneath; samaras red. 

 Rocky mountain tree; leaves small, their lobes coarsely toothed. 

 B. Leaves pinnately compound, often trifoliolate (Ash-leaved Maples). 

 United part of the samaras distinctly constricted at the base, 



stipe-like; leaves thin; eastern tree. 

 United part of the samaras not constricted at the base, or but 

 slightly constricted; leaves firm; western trees. 

 Foliage densely pubescent; Califomian tree. 

 Foliage not densely pubescent. 



Samara-wing adnate to the body only to or above the middle 

 Samara-wing adnate to the body down to the point of 

 coherence; Utah tree. 



I. A. spicatum. 



2. yl. pennsylvanicum. 



3. A. macrophyllum. 



4. A. circinatum. 



5. A. modocense. 



6. A. glahrum. 



7. A. Douglasii. 



8. A. saccharinum. 



9. A. ritbrum. 



10. A. stenocarpum. 



11. A. carolinianum. 



12. A. Drummondii. 



13. A. Sacchariim. 



14. A. nigrum. 



15. A. floridannm. 



16. A. lencoderme. 



17. A. grandidentatmn. 



18. A. Negundo. 



ig. A. call for uicum. 



20. .1. interior. 



21. A. Kingii. 



