ROSACEAE 



American Mountain-ash 



Sorbus americana Marsh. [Pyrus americana (Marsh.) DC] 

 {Sorbus sitchensis Roem.) 



HABIT. A shrub or small tree, seldom 30 feet high and 12 

 inches in diameter; crown round-topped, handsome; with 

 spreading, slender branches. 



LEAVES. Alternate; pinnately compound; 6-8 inches long; 

 with 7-17 mostly sessile leaflets; oblong-oval to lanceolate; 

 2-4 inches long and 1/^-1 inch wide; serrate; glabrous; dark 

 green above, pale below; deciduous. 



FLOWERS. Regular; perfect; small; in broad, flat cymes 

 3-5 inches across; on short, stout pedicels; appearing after 

 leaves; 5 petals, cream-white, H inch in diameter. 



FRUIT. Berry-like pome; subglobose; Va-Yi inch in diam- 

 eter; bright orange-red; thin, acrid flesh; papery carpels. Seed: 

 1 or 2 in each cell, Y^ inch long, ovoid, brown. 



TWIGS. Stout; round; red-brown and pubescent, becoming 

 dark brown and glabrous; marked by large leaf scars and oblong 

 lenticels. Winter buds: terminal Ya-Va inch long, acute, dark 

 red, pilose, with gummy exudation. 



BARK. Thin {Y& inch); light gray; smooth or slightly rough- 

 ened by scales; inner bark fragrant. 



WOOD. Light; soft; weak; close-grained; diff'use-porous ; 

 heartwood pale brown; sapwood thick and lighter colored. 



SILVICAL CHARACTERS. Intolerant; slow-growing; short- 

 lived, abundant seeder; fibrous roots; prefers moist sites, but 

 grows well on rocky hillsides; often cultivated. 



GENERAL. The taxonomy within this genus is confused. 



The western form of this species, S. americana var. sitchensis (Roem.) 



Sudw., is usually a shrub and its distribution is included in the 



map. The following key separates the native and naturalized 



species reaching tree size: 



I. Winter buds densely covered with long white hairs; leaflets 1-2 

 inches long, oblong; widely planted and naturalized through the 



northern United States and Canada 



S. aucuparia L., European Mountain-ash 



1. Winter buds glabrous or slightly hairy; leaflets XYi-^ inches long. 

 2. Winter buds glabrous or slightly white-hairy; leaflets usually 



lanceolate and acuminate 



S. americana Marsh., American Mountain-ash 



2, Winter buds slightly red-hairy; leaflets oblong, short-pointed; 



Northeast and Central states 



S. decora Schneid., Showy Mountain-ash 



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