166 Proceedings of flic Ohio State Academy of Science 



3. Leaves without stipules. 4. 



4. Leaves with much milky sap in the petiole, glaljrous, dark green 



above, lighter below, usually with 7 prominent palmate veins; 

 tlowers corymbose, unfolding with the leaves: wings of the fruit 

 diverging nearly in a straight line ; i)etals present ; winter buds 

 rounded. A. platanoidcs. 



4. Leaves with watery or frothy sap, pale and nearly glabrous beneath, 



usually with 5 [jrominent palmate veins : flowers corymbose, un- 

 folding with the lca\e> ; wings of the fruit diverging a little less 

 than a right angle; ])e.;.L nme; winter Inids pointed. A. sacclia- 



lUIII. 



5. Leaves very sharply and finely serrate, :^-lobed at the outer end, 



widest above the middle, the lobes abruptly narrow-acuminate, 

 brown pubescent below wlien young; twigs green, striped with 

 darker lines; flowers racemed, terniin.al. imfolding after the leaves. 

 A. pciinsylvanicum. 



h. Leaves dentate-serrate or lol)e:l, not aliruptly narrow-acuminate; 

 twigs not striped, fi. 



(i. Leaves broadly 3-5-lobed, the loljes rather regularly and continuously 

 dentate-serrate or dentate-crennte ; flowers racemed, terminal, un- 

 folding after the leaves. 7. 



0. Leaves usually with :^-7 slender, long and pointed lobes, the lobes 

 irregularly or interruptedly serrate or serrate-dentate; flowers in 

 dense sessile lateral clusters, appearing before the leaves. 8. 



7. Leaves longer than wide, slightly 3-lobcd at the outer end, usually 

 rnly very slightly lol)ed at tiie lower end, not glaucous below; 

 l)ark of twigs green or grayish : racemes erect ; a shrub, rarely 

 a small tree. A. spicatum. 



7. Leaves as broad or broader than long, prominently 5-lobed, glabrous 



and dark green above, pultescent and light glaucous below, on 

 long reddish petioles ; bark of twigs reddish-brown ; racemes 

 drooping ; wings of fruit pubescent, moderately spreading : a large 

 tree. A. pseudo-platanus. 



8. Leaves usually deeply 5-lobed, lobes slender, acute, white and glaucous 



beneath ; notches between the lobes often somewhat rounded ; 

 fruiting pedicel short and stiff, 1-2 in. long; wings divergent; 

 petals none. A. saccharinuui. 

 8. Leaves sharply 3-5-lobed, whitish glaucous beneath, notches acute; 

 fruiting pedicel long, slender and drooping, 2-4 in. long ; wings 

 incurved ; petals present. A. rubrum. 



I. Acer saccharinum I.. Sihcr ATaple. A lar^e tree 

 with flaky bark, the twig.s often reddish, self-pruned b}' basal 

 joint.^. Leaves deeply 5-lobed, the lobes rather narrow, acumi- 



