494 



ACERACEAE. Vol. II. 



Family 79. ACERACEAE St. Uil. Expos. 1-am. 2: 15. 1805. 



}vI.\PLE Family. 



Trees or shrubs, with watery often saccharine sap, opposite simple and 

 palmately lobed (rarely entire) or pinnate leaves, and axillary or terminal cymose 

 or racemose regular polygamous or dioecious Howers. Calyx generally 5-partcd, 

 the segments imbricated. Petals of the same number, or none. Disk thick, 

 annular, lobed, sometimes obsolete. Stamens 4-12, often 8; filaments filiform. 

 Ovary 2-lobed, 2-celled ; styles 2, inserted between the lobes. Fruit of 2 winged 

 samaras, joined at the base and i-seeded (rarely 2-seeded). Seeds compressed, 

 ascending; cotyledons thin, folded. 



The family consists of the following genus and Dipteronia Oliver, of central Asia, which differs 

 from Acer in the samara being winged all around. There are more than 100 species of Maples. 



I. ACER [Tourn.] L. Sp. PI. 1055. i753- 



Besides the following, some 8 others occur in southern and western North America, 

 species: Acer Pseudo-('latanus L. 



Leaves simple, palmately lobed. 



Flowers in dense sessile lateral clusters, unfolding before the leaves. 

 Petals none ; ovary tomentose : samaras divergent. 

 Petals present ; ovary glabrous ; samaras incurved. 



Leaves pale and glabrous or but slightly pubescent beneath. 

 Leaves bright green above, mostly 5-lobed. 



Wings of the samara broadened above the middle. 

 Wings of the samara linear, scarcely broadened above. 

 Leaves dark green above, mostly 3-lobed. 

 Leaves densely whitish-pubescent beneath ; southern. 

 Flowers corymbose. lateral, unfolding with the leaves. 

 Flowers long-pedicelled. drooping ; large trees. 

 Leaves pale and nearly glabrous beneath. 

 Leaves green and pubescent, at least on the veins, beneath. 

 Flowers short-pedicelled, erect ; shrub or small tree ; western. 

 Flowers racemed, terminal, unfolding after the leaves. 

 Racemes drooping ; leaves finely serrate. 

 Racemes erect ; leaves coarsely serrate. 

 Leaves pinnate. 



Type 



I. A. saccharinum. 



2. A. riibrum. 



3. A. slenocarpum. 



4. .-/. carolinianiim. 



5. A, Drummondii, 



6. A. Saccharum, 



7. A. nigrum. 



8. A. glabrum. 



9. A. pennsylvaniciim. 



10. A.spicatnm. 



11. A.Negundo. 



Acer saccharinum L. Silver Maple. Soft or White Maple. Fig. 2804. 



Acer saccharinum L. Sp PI. 1055. 1753- 



Acer dasycarpum Ehrh. Beitr. 4: 24. 1789. 



Acer eriocarpum Michx. Fl. Bor. Am. 2: 253. 1803. 



A large tree with flaky bark, maxinium height of 

 ioo-i20 and trunk diameter of 3-5- Leaves 4-6' 

 long, deeply 5-lobed, the lobes rather narrow, acuminate, 

 coarsely and irregularly dentate, truncate or slightly cor- 

 date at the base, green above, silvery white and more 

 or less pubescent beneath, especially when young; flow- 

 ers greenish to red, in nearly sessile lateral corymbs 

 much preceding the leaves; calyx obscurely lobed ; petals 

 none; fruiting pedicels elongating; stamens 3-6; samaras 

 pubescent when young, divaricate, at length 2' long, 

 the wing often 6" wide. 



.Along streams, New Brunswick to Florida, west to 

 southern Ontario. South Dakota. Nebraska and Oklahoma. 

 The samaras are frequently unequally developed. Wood 

 hard, strong, light colored ; weight per cubic foot 32 lbs. 

 Used for furniture and floors. Maple sugar is made from 

 the sap in small quantities. River-, silver-leaf-, creek-, 

 ^ water- or swamp-maple. Feb.-April. 



Acer Pseudo-Platanus L., svcamore-maple. with terminal drooping racemes of yellowish flowers 

 with very woolly ovaries, and deeply 3-S-!obed leaves, and Acer platanoides L.. Norway maple, 

 with terminal corymbs of greenish yellow flowers appearmg with or before the 5-7-lobed lea\es, 

 commonly planted, have occasionally escaped from cultivation. 



