552 ACERACEAE 



same number, inserted on the margins of an indistinct disk, or very often 

 wanting. Stamens 4-9, often 8. Gynoecium of two united carpels; styles 

 united. Fruit of 2 winged carpels, united below (samaras). 



Leaves palmately lobed or rarely palmatedly compound; flowers polygamous or perfect. 

 Leaves pinnately compound; flowers dioecioiis. 2*. Negundo. 



1. Acer (Toum.) l. Maple. 



Trees or rarely shrubs. Leaves opposite, petioled, more or less palmately 



lobed or cleft, rarely palmately compound. Flowers polygamous or rarely 



perfect, regular, m axillary or terminal racemes or cor^Tnbs. Sepals 4 or 5, 



mrely &-9. Disk cup-shaped, lobed, or more commonly obsolete or wanting. 



btamens 4-9. Petals as many as the sepals or wanting. Samaras 2, with reticu- 

 late wings. 



Flowers in racemes or corymbs; petals and sepals both present; disk well developed r 



lobes of the leaves toothed. . 



Flowers in long racemes, appearing after the leaves; leaves long-acuminate, with 

 small lateral lobes; petals longer than the sepals. 1. A. spicatum. 



1- lowers corymbose, appearing with the leaves; leaves not long-acuminate, deeplr 



d-5-ciett; ternunal lobe only slightly larger; petals and sepals greenish. sub- 

 Bark of the one-year-old branches graj-lsh; leaves and their lobes acuminate, not 



dotted beneath. 



terminal 



ovate. 2 A Douglasii^ 



Sinuses between the leaf-lobes deep and narrow; terminal lobe rhombic. 



TJ-, I <• 4.1, , , , 3. A. glabrum, 



±iark of the one-year-old branches white; leaves and their lobes acute, not acum- 

 mate, with more or less numerous glandular red dots beneath. 



Flowers in umbels, appearing with the leaves; petals lacking; lobes of tiie'^leaves sinuate. 



5. A. grandidentatum^ 



1. A. spicatum Lam. Shrub or small tree, sometimes 10 m. high, with 

 thin smooth bark; twigs somewhat velutinous-puberulent or glabrate in age; 

 leaf-blades longer than broad, cordate, 3-lobed, glabrate above, paler and pubes- 

 cent beneath; petals hnear or spatulate; samaras about 2 cm. long; wings ascend- 

 ing-spreading at about 90°; backs nearly straight. Rocky woods and mountain 

 slopes: Newf.— Ga.— Minn.— Sask. Boreal My-Je. 



2. A. Douglasii Hook. Shrub or small tree, sometimes 10 m. high; twigs 

 glabrous purphsh or red; older branches grayish; leaf-blades broadly cordate in 

 outline, 3-10 cm. long and about as broad, 3-5-Iobed, or on young shoots and 

 vigorous twags sometimes 3-divided to the base, glabrous on both sides; samaras 

 A ^?' ^^^' ascending, usually incurv^ed on the back; sinus usually rounded. 



A sxibserraium Greene. Hills and mountain sides: Alta.— Wyo.— Ore.— B.C. 



ubmonL — MonL Ap- Je. 



A^r T^" ^^^^™^ Torrey. Usually a small tree, 5-15 m. high; twigs glabrous, 

 reddish; older branches gray; leaf-bl?des broadly cordate or rounded-reniform 

 in outlme 4-8 cm. long, 4-10 cm. wide, glabrous, 5-7 lobed, or usually on young 

 shoots and vigorous branches or sometimes on the whole tree 3-divided to the 

 base; samaras 2.5-3 cm. long, usually straight on the back; sinus usuallv acut^ 

 A neonwxicamim Greene. Mountains, usually along streams: S.D.— N.M. 

 Utah— Wyo. Submont.—MonL My-Je. 



1 f*Ki^^' tripartitum Nutt. Shrub 1-5 m. high: twigs reddish, glabrous; 

 leat-blades rounded-reniform m outline, glabrous above, more or less puberulent 

 beneath shmmg, 3-o-lobed or -cleft or sometimes [as m the type spechnens] 3- 

 parted to the base, the terminal lobe more or less rhombic, coarsely toothed, 

 z-4 cm long, 2-5 cm. wide; samaras 2-2.5 cm. long, ascending, incurved on the 

 back, tormmg with each other a narrow angle. Dry hills: Wyo.— Utah— s 

 Cahf. Son,—SubmonL My-Je. ^ j j 



..^'y^^e^^^^^^^i^tVLia Nutt. Shrub or rarely a small tree, 5 m. high, 

 with light brown twigs and gray branches; leaves reniform or orbicular in out- 

 line, deeply 3-5 lobed, with roimded sinuses, e-lahrmi^ t^oIa «nrl vplutinous 



