ACERACEAE 



BOXELDER 

 Acer negundo L. 



HABIT. A small tree, rarely 75 feet high and 4 feet in diam- 

 eter; trunk usually irregular and dividing near ground into 

 several, stout, wide-spreading branches. 



LEAVES. Compound, 3 (rarely 5-7) leaflets; petiole long, 

 slender, puberulous; leaflets ovate to lanceolate, 3-4 inches 

 long, and 1 ^-4 inches wide, glabrous, acuminate, coarsely 

 serrate and sometimes 3-lobed at base. 



FLOWERS. Dioecious; minute; the male fascicled; the 

 female in drooping racemes; appearing with leaves or a little 

 before them; calyx 5-lobed, hairy, yellow-green; corolla absent; 

 stamens 4-6 with slender, exserted, hairy filaments; ovary hairy, 

 partly enclosed by calyx. 



FRUIT. Pendent; 1-2 inches long; glabrous; ripening in 

 autumn; in drooping racemes 6-8 inches long. Seed: narrowed 

 at the ends, smooth, bright red-brown, Yi inch long. 



TWIGS. Moderately stout; greenish; pubescent, or rarely 

 nearly glabrous; marked by conspicuous bud scale scars and 

 crescent-shaped leaf scars which surround the twig. Winter 

 buds: acute, Vk-V^ inch long, tomentose. 



BARK. Thin {Va-Vi inch); pale gray or light brown; deep- 

 ly divided by furrows into broad, rounded ridges. 



WOOD. Light, soft, close-grained, weak; heartwood cream- 

 white to yellow-brown, often streaked; sapwood thick; used 

 occasionally for cheap furniture, woodenware, etc. 



SILVICAL CHARACTERS. Upper Sonoran and Transi- 

 tion zones; moderately tolerant; shallow-rooted, except on deep 

 soils; hardy to extremes of climate; rapid grower but short- 

 lived and usually of poor form; reproduction by sprout and seed 

 plentiful. 



GENERAL. Five varieties are recognized: arizonicum Sarg. 

 in Arizona and New Mexico, with serrate leaves and glabrous 

 leaves, twigs, and petioles; calif ornicum Sarg. in California, 

 with coarsely serrate or nearly entire leaflets with matted hairs 

 on the lower surface; interius Sarg. through the west, with hairy 

 twigs and petioles; texanum Pax through the southeast, with 

 woolly twigs and lower leaf surface; and violaceum J. and B. 

 through the northern half of the United States, with bluish gla- 

 brous twigs and entire or dentate leaves hairy on the lower surface. 

 The distribution of all varieties is included on the map. 



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