100 SILVA OF NORTH AMERICA. SAPINDACEE. 
lobed with entire or bluntly toothed lobes, and often appear almost peltate by the overlapping of the 
sides of the deep narrow basal sinus. They are frequently thinner than those of the common form of 
the Sugar Maple, are usually green on the lower surface, which is often villous-pubescent, especially 
along the principal veins and on the petioles, and sometimes are six or eight inches across, although 
varying considerably in size.'| The Black Sugar Maple is generally found on lower ground than the 
common form, occupying, as a rule, the banks of streams or rich alluvial river-bottom lands. It has 
been noticed on the shores of Lake Champlain in Vermont, and spreads as far west as southwestern 
Arkansas and eastern Kansas, ranging southward west of the Alleghany Mountains to northern Ala- 
bama and to the valley of the Chickasaw River in Mississippi.” 
Acer barbatum in the Gulf states passes into a form® having small three to five-lobed leaves an 
inch and a half to three inches across, with obtuse entire or obscurely toothed lobes, truncate or slightly 
cordate at the base, and pale and sometimes thickly covered by hairy pubescence on the lower surface, 
and having flowers and fruit barely half the size of those of the ordinary form, the wings of the samaras 
This is a small tree inhabiting upland woods, and in 
It is 
nowhere common, although distributed from western Florida to the valley of the upper Cibolo River in 
rising nearly at right angles from the nutlets. 
western Texas, where it is reduced to a low shrub, found only along the banks of streams. 
Texas, and the Sierra Madre of Nuevo Leon. 
Acer barbatum reappears in the mountainous regions of the interior of the continent in another 
form * very similar to the last. The leaves of the mountain Sugar Maple are three-lobed and slightly 
cordate or truncate at the base, with broad shallow sinuses and acute or obtuse lobes which have nearly 
entire or sinuous margins, or sometimes are somewhat three-lobed ; they are two or three inches across, 
rather pale on the upper, much paler and at maturity slightly pubescent on the lower surface along the 
principal veins, and are borne on slender petioles an inch or an inch and a half long; the flowers and 
fruit’ are smaller than those of the eastern tree. This is a small tree, rising occasionally to the height 
of thirty or forty feet, with a trunk eight or ten inches in diameter covered with thin dark brown bark, 
the surface of which separates into plate-like scales. It grows at an elevation of from five to six thou- 
sand feet above the sea-level, and is rare and local, forming occasionally with the Aspen small groves 
on the banks of streams. It occurs on the headwaters of the Columbia River in northern Montana, 
1 Professor L. H. Bailey calls attention to the fact that the sides 
of the large leaves of the Black Maple as it grows in some parts of 
shown by the Census tests is 0.6915, a cubic foot weighing 43.09 
pounds. 
central Michigan droop and hang down like pieces of old limp 8 Acer barbatum, var. Floridanum, Sargent, Garden and Forest, 
iv. 148. 
A. saccharinum, var. Floridanum, Chapman, Fl. 80. — Wesmael, 
thick cloth. This peculiarity is particularly noticeable when the 
leaves are fully grown, and gives the tree a heavier and duller as- 
pect than that of the common Sugar Maple, making it possible to 
distinguish the two trees at some distance (Popular Gardening, iii. 
24; Bot. Gazette, xiii. 214). More remarkable is the occasional 
occurrence on some Indiana and Michigan trees of large foliaceous 
and caducous puberulous or small rudimentary stipules, organs 
otherwise unknown in the genus. (A. Gray, Am. Nat. vi. 764; 
vii. 422.— Wheeler, Cat. Mich. Pl. 23.— Bailey, l. c.) They are 
apparently abnormal, although reproduced year after year on 
some trees, and cannot be relied on to distinguish this plant specifi- 
cally, as no trace of them appears on such specimens from other 
parts of the country as I have been able to examine. Extreme 
forms of the Black Maple, like those found in Michigan, are easily 
recognized and appear distinct, but they seem to pass gradually by 
many intermediate forms into the plant which is usually regarded 
as the type of the species, and it is not easy to find characters suf- 
ficiently constant to establish satisfactorily the Black Maple even as 
a variety. 
2 The wood of the Black Maple is not distinguishable from that 
of the common Sugar Maple, and is used commercially for the same 
purposes. The specific gravity of the absolutely dry wood as 
Gen. Acer, 45. 
A. Mexicanum, Gray, Proc. Am. Acad. v. 176. — Hemsley, Bot. 
Biol. Am. Cent. i. 214. 
A. Floridanum, Pax, Engler Bot. Jahrb. vii. 243. 
* Acer barbatum, var. grandidentatum, Sargent, Garden and For- 
est, iv. 148. 
Acer grandidentatum, Nuttall; Torrey & Gray, Fl. N. Am. i. 
247 ; Sylva, ii. 82, t. 69. — Dietrich, Syn. i. 1283. — Walpers, 
Rep. i. 409. — Watson, King’s Rep. v. 52; Pl. Wheeler, 7. — Parry, 
Am. Nat. ix. 201, 268. — Rothrock, Wheeler’s Rep. vi. 83. — Rusby, 
Bull. Torrey Bot. Club, ix. 106.— Sargent, Forest Trees N. Am. 10th 
Census U. S. ix. 48.— Pax, Engler Bot. Jahrb. vii. 220. — Wes- 
mael, Gen. Acer, 30. 
° In a specimen collected by Professor H. H. Rusby on the Mo- 
gollon Mountains, and in specimens gathered by Marcus E. Jones in 
Utah, the fruit is as large and hardly distinguishable from that of 
the eastern Sugar Maple. Occasionally, however, it is not half so 
large ; and on a specimen collected by Pringle in the Huachuaca 
Mountains on the first of July, the fruit is apparently fully grown 
and has small pink wings. 
