SAPINDACEZ. 
SILVA OF NORTH AMERICA. 95 
ACER GLABRUM. 
Dwarf Maple. 
FLOWERS in terminal racemose corymbs; petals linear, as long as the sepals. 
Leaves 3-lobed or 8-parted. 
Acer glabrum, Torrey, Ann. Lyc. N. Y. ii. 172; Bot. 
Wilkes Explor. Exped. 259.— Don, Gen. Syst. i. 650. — 
Torrey & Gray, Fl. N. Am. i. 247, 684. — Walpers, Rep. 
i. 409. — Nuttall, Sylva, ii. 86.— Newberry, Pacific f. 
fi. Rep. vi. 69. — Cooper, Smithsonian Rep. 1858, 258 ; 
Pacific R. R. Rep. xii. 51, 57; Am. Nat. iii. 406. — 
Gray, Am. Jour. Sci. ser. 2, xxxiv. 259; Proc. Phil. 
Acad. 1863, 59. — Watson, King’s Rep. v. 52. — Brewer 
& Watson, Bot. Cal. i. 107.— Rothrock, Wheeler’s Rep. 
vi. 83. — Sargent, Forest Trees N. Am. 10th Census U. S. 
ix. 47. — Coulter, Man. Rocky Mt. Bot. 49. — Pax, En- 
gler Bot. Jahrb. vii. 218. — Wesmael, Gen. Acer, 30. — 
Greene, Fl. Francis. i. 76. 
. Douglasii, Hooker, London Jour. Bot. vi. 77, t. 6. — Pax, 
Engler Bot. Jahrb. vii. 219. — Wesmael, Gen. Acer, 30. 
. tripartitum, Nuttall; Torrey & Gray, Fl. N. Am. i. 
247. — Dietrich, Syn. ii. 1281. — Walpers, Rep. i. 409. — 
Nuttall, Sylva, ii. 85, t. 71. — Gray, Pl. Fendler. 28 
(Mem. Am. Acad. n. ser. iv.); Pacific kh. KR. Rep. iv. 
73. — Newberry, Pacific Rk. R. Rep. vi. 69. 
. glabrum, var. tripartitum, Pax, Engler Bot. Jahrb. 
vii. 218. 
A low bushy tree, rarely twenty or twenty-five feet in height, with a short trunk six or eight inches 
in diameter covered with smooth reddish brown bark, and slender upright branches; or more often a 
shrub four or five feet high. The branchlets are at first pale grayish brown, often slightly many-angled 
on vigorous shoots, and quite glabrous; they become bright red-brown during the first winter, and are 
then conspicuously marked at the base by the scars left by the falling of the accrescent inner bud-scales. 
The winter-buds are acute, an eighth of an inch long, and covered with vivid red or occasionally yellow 
scales ; the second pair of scales are bright rosy red, and more or less hairy-pubescent, especially within, 
while those of the inner ranks are pale brown tinged with pink, and at maturity are sometimes an inch 
and a half long, narrowly spatulate, very thin, and tomentose on the inner surface. The leaves are 
glabrous, membranaceous, rounded in outline, cordate-truncate or wedge-shaped at the base, and three 
to five-lobed, or often three-parted or three-foliolate, with acute or obtuse, doubly serrate lobes; they 
are from an inch to five inches across, rather conspicuously veined, dark green and lustrous on the 
upper, and paler on the lower surface, and are borne on stout grooved petioles which vary in length 
from one to six inches, and are often bright red.’ The staminate and pistillate flowers are usually pro- 
duced separately on different plants in loose few-flowered glabrous racemose corymbs borne on slender 
drooping peduncles from the ends of two-leaved branchlets. The sepals are oblong, obtuse, petaloid, 
and as long as the greenish yellow petals. There are seven or eight stamens with glabrous unequal 
filaments, which in the sterile flower are shorter than the petals, and much shorter or rudimentary in 
the fertile flower. 
short obtuse lobes, and is surmounted with a style that divides at the base into two spreading stigmatic 
lobes the length of the petals. The fruit is glabrous, and an inch or rather less in length, with broad 
nearly erect or slightly spreading wings which are often rose-colored during the summer. The seeds 
are ovate, with a bright chestnut-brown testa and thin foliaceous cotyledons. 
Acer glabrum is widely distributed from British Columbia over the mountain ranges of western 
America, extending south in California along the Sierra Nevada Mountains to the Yosemite valley, and 
The ovary, which is rudimentary or wanting in the sterile flower, is glabrous, with 
reaching the eastern slope of the Rocky Mountains of Colorado and the mountains of eastern New 
Mexico and western Arizona. It is found on the borders of mountain streams, usually at an elevation 
1 It is not unusual to find lobed and trifoliate leaves on the same branches. 
