[48 ROSE FAMILY 



Key to the Species. 



1. Leaflets acuminate, smooth on both sides; fruit 



4-6 mm. long S. americana 



2. Leaflets more or less obtuse, thicker; fruit 6-12 



mm. long 



a. Leaflets pubescent below, especially along the 



veins; native S. sambucifolia 



b. Leaflets always more or less pubescent or 



tomentose on both sides; cultivated S. aucuparia 



Sorbus americana Marshall 1785 American Mountain Ash 

 Pyrus americana De Candolle 1825 



Small tree, 6-7 meters (18-21 ft.) high; bark smooth, light gray, with 

 small plate-like scales; winter buds acute, 8- 18 'mm. long, scales dark red, 

 pilose with gummy secretion; leaves 15-20 cm. long, petiole green or red, 

 leaflets 13-17, oblong-lanceolate, sessile, rounded at base, acuminate at 

 apex, sharply serrate, glabrous on both sides, bright green above, paler be- 

 neath, 5-8 cm. long, 1-2 cm. wide; inflorescence flat, 10-15 cm. broad, 

 flowers cream-white, 4-6 mm. broad, calyx obconic; petals contracted 

 below into a short claw; fruit sub-globose, 4-6 mm. in diameter, bright 

 red, flesh thin, sour : americana, American. 



In woods of the northern part of the state. Distributed from Labrador 

 to Manitoba, south into northern N. E., N. Y., and the Great Lakes region, 

 extending south in the mountains to N. C. 



Flowers in May and June, fruits in Sept. and Oct. Sometimes planted 

 as an ornamental tree. The wood close grained, light, soft and weak, 

 pale brown, weight 34 lbs. 



Sorbus sambucifolia (C. & S.) Roemer 1847 Western Mountain 



Ash 

 Pyrus sitchensis (Roemer) Piper 1906 

 Pyrus sambucifolia C. & S. 1827 



Small tree, 6-10 meters (18-30 ft.) high; bark gray and smooth with 

 small scales; winter buds 18-20 mm. long, acute, scales dark red and 

 slightly hairy; leaves 10-15 cm. long, petioles usually bright red or green, 

 leaflets 7-15, oblong to lance-ovate, base rounded and unequal, apex obtusr 

 or abruptly pointed, sharply and sometimes doubly serrate, with spreading 

 teeth, dark green and glabrous above at maturity, paler beneath and 



