ROSACEZ. 
SILVA OF NORTH AMERICA. 79 
PYRUS AMERICANA. 
Mountain Ash. 
LEAFLETS lanceolate, acuminate. 
Pyrus Americana, De Candolle, Prodr. ii. 637. — Watson, 
Dendr. Brit. i. 54, t.54. —Sprengel, Syst. ii. 511.— Hooker, 
Fl. Bor-Am. i. 204.— Don, Gen. Syst. ii. 648. — Audu- 
bon, Birds, t. 363. — Torrey & Gray, Fl. N. Am. i. 472. — 
Torrey, Fl. N. Y. i. 224. — Dietrich, Syn. iii. 155. — Nut- 
tall, Sylva, ii. 25, t. 50. — Emerson, Trees Mass. 439. — 
Lam. Dict. Suppl. v. 164. — Nuttall, Gen. i. 305. — Hayne, 
Dendr. Fl. 75. — Spach, Hist. Vég. ii. 95. — Bigelow, FV. 
Boston. ed. 3, 207. — Roemer, Fam. Nat. Syn. iii. 138. — 
Koch, Dendr. i. 190. — Maximowiez, Bull. Acad. Sci. St. 
Pétersbourg, xix. 174 (Mél. Biol. ix. 171). —Wenzig, Lin- 
ned, xxxviii. 71.— Decaisne, Nouv. Arch. Mus. x. 158. 
Lange, Pl. Grenl. 134. — Provancher, Flore Canadienne, 
i. 209. — Chapman, FV. 129. — Curtis, Rep. Geolog. Surv. 
NV. Car. 1860, iii. 70.— Brewer & Watson, Bot. Cal. i. 
189. — Sargent, Forest Trees N. Am. 10th Census U. S. 
ix. 73. — Watson & Coulter, Gray’s Man. ed. 6, 164. 
Sorbus Americana, Marshall, Arbust. Am. 145. — Willde- 
now, Hnum. 520. — Pursh, Fl. Am. Sept. i. 341. — Poiret, 
Sorbus aucuparia, Poiret, Lam. Dict. vii. 234 (in part). — 
Bigelow, £7. Boston. 119. — Decaisne, Nowv. Arch. Mus. 
x. 158 (in part). 
Sorbus aucuparia, var. Americana, Persoon, Syn. ii. 38. 
Pyrus aucuparia, Meyer, Pl. Lab. 81 (in part). — Schlecht- 
endal, Linnea, x. 99 (not Geertner).— Hooker f. Trans. 
Linn. Soc. xxiii. 290, 3827 (Distribution Arctic Pi.), in part. 
A tree, twenty to thirty feet in height, with a trunk which rarely exceeds a foot in diameter, 
spreading slender branches, and stout branchlets ; or more often a tall or sometimes a low shrub sending 
up many stems from the ground. The bark of the trunk is an eighth of an inch thick, with a smooth 
light gray surface irregularly broken by small appressed plate-like scales. The branchlets are slightly 
clothed at first with fine pubescence, but soon become glabrous, and in their first winter are brown 
tinged with red, marked by the large leaf-scars and remote pale oblong lenticular spots, and often cov- 
ered with a faint glaucous bloom; in their second year they become darker, and the thin papery outer 
The winter-buds 
are acute, from one quarter to three quarters of an inch long, and protected by dark vinous red acumi- 
layer of bark is easily separable from the bright green and fragrant inner layers. 
nate scales rounded on the back, more or less pilose, and covered with a gummy exudation; the inner 
scales are coated in the bud with thick pale tomentum and enlarge with the growing shoots which, in 
falling, they mark with enduring narrow ring-like scars. The leaves are six to eight inches long, 
with slender grooved dark green or red petioles often furnished with tufts of dark hairs at the base of 
the petiolules and enlarged at the base, and from thirteen to seventeen leaflets; these are lanceolate, 
acute, taper-pointed, unequally wedge-shaped or rounded and entire at the base, and sharply serrate 
above, with acute often, glandular teeth ; they are sessile or shortly petiolulate, or the terminal one is 
sometimes borne on a stalk half an inch in length; when they unfold they are slightly pubescent on 
the lower surface, and at maturity are membranaceous, glabrous, dark yellow-green on the upper, and 
pale on the under surface, two to three inches long, and one half to two thirds of an inch broad, with 
prominent midribs grooved on the upper side, and thin veins. The stipules are broad and foliaceous, 
nearly triangular, variously cut, and caducous. The leaves turn a bright clear yellow before falling. 
The flowers, which appear after the leaves are fully grown toward the end of May or as late as July at 
the north and on the high Alleghany Mountains, are one eighth of an inch in diameter when expanded, 
and are borne on short stout pedicels in flat compound cymes three or four inches across. The bracts 
and bractlets are acute, minute, and caducous. The calyx is broadly obconic and puberulous, with 
short nearly triangular lobes tipped with minute glands, and half the length of the nearly orbicular 
creamy white petals which are contracted below into short claws. The fruit is a quarter of an inch 
