ACERACEAE 741 
Flowers in lateral clusters : 
Clusters expanding before the leaves, sessile or nearly so, not drooping. 
Petals wanting or obsolete : ovary pubescent. 1. A. saccharinum. 
Petals present : ovary glabrous. 
Leaf-blades glabrous or glabrate beneath : samaras less than 4cm. long: 
1 
wings rather spr ing. 2. A. rubrum. 
Leaf-blades copiously woolly beneath : samaras over 4 cm. long; wings 
nearly contiguous. 8. A. Drummondii. 
Clusters expanding with the leaves, drooping. 
Trunks with gray or nearly black bark: samaras mostly over 3 em. long. 
Leaf-blades scarcely paa beneath than above: lobesentire or undulate. 4. A. nigrum. 
Leaf-blades pale or gisucous beneath : lobes coarsely toothed. 5. A. Saccharum. 
Trunks with white bark : samaras mostly less than 2.5 cm. long. 
Leaf-blades glaucous and sometimes pale-pubescent beneath : samaras 
light green. 6. A. Floridanum. 
Leaf-blades green and velvety beneath : samaras red. 7. A. leucoderme. 
Flowers in terminal racemes or panicles. 
Flowers in panicles: petals linear or linear-spatulate, twice or thrice as long 
as the sepals: samaras less than 2.5 cm. long. . 8. A. spicatum. 
Flowers in racemes: petals oblong, about as long as thesepals : samaras over 
2.5 em. long. 9. A. Pennsylvanicum. 
1. Acer saccharinum L. A tree rarely 36 m. tall, with a maximum trunk diameter 
of about 1.5 m., the bark flaky at maturity, gray, or that of the twigs reddish brown : leaves 
appearing after the flowers; blades about as long as broad, 10-15 cm. long, with 3-5 
prominent incised lobes longer than the body, silky when young, glabrate, bright green 
above, glaucous or silvery-white beneath, truncate or cordate at} the base: flower-clusters 
sessile or nearly so: calyx greenish or yellowish: stamens exserted : fruit drooping: 
samaras 5-6 cm. long, tomentose or glabrate at maturity, at length widely spreading. [A. 
dasycarpum Ehrh. ] 
In woods and river swamps, New Brunswick to Ontario. North Dakota, Florida'and the Indian 
Territory. Late winter and spring. SILVER MAPLE. SOFT MAPLE. WHITE MAPLE. RIVER MAPLE. 
` 2. Acer rübrum L. A tree, sometimes 35 m. tall, with a maximum trunk diameter 
of about 13 dm., the bark fissured on the trunk, smooth and pale or white-gray on the 
branches. Leaves appearing after the flowers; blades as broad as long or often longer 
than broad, deep green above, pale or glaucous and glabrate beneath, shallowly 3-5-lobed, 
rather evenly serrate, rounded or subcordate at the base: flower-clusters dense, red or 
quovis, appearing before the leaves from the ends of short branchlets or in the axils of 
ast year's leaves ; the pistillate with longer pedicels than the staminate : sepals nearly dis- 
tinct: petals narrower than the sepals: ovary glabrous or glabrate: fruit drooping from 
the elongating pedicels, commonly red : samaras less than 4 mm. long, the wings diverging 
at about 45 degrees. 
In low grounds and swamps, New Brunswick to Manitoba, Florida and Texas. Late winter and 
early spring, RED MAPLE. SWAMP MAPLE. WATER MAPLE. SCARLET MAPLE. 
. 3. Acer Drummóndii Hook. & Arn. A tree Par eh ia height of 26 m., with a max- 
imum trunk diameter of about 1 m., the bark pale or whitish, rough on the trunk. Leaves 
appearing after the flowers; blades varying from ovate to depressed orbicular in outline, 
8-15 cm. broad or sometimes smaller, 3-lobed, coarsely and irregularly toothed, deep green 
above, white and woolly beneath, rounded or cordate at the base: flower-clusters red, ter- 
minating short anche in the axils of last year's leaves, the pistillate with longer 
pedicels than the staminate : sepals nearly distinct, oblong or vi md narrowed upward : 
petals nearly like the sepals only narrower: ovary say Sag ruit drooping from the 
slender pedicels : samaras over 4 cm. long, the wings tending to converge. 
In river swamps, Missouri to Georgia, Florida and Texas. Spring. RED MAPLE. 
. 4. Acer nigrum Michx. f. A forest tree sometimes 40 m. tall, with a maximum trunk 
diameter of fully 1.5 m., the bark dark, coarsely flaky. Leaves eppeariug with the flowers ; 
es mainly broader than long, often 15-20 cm. broad, relatively thin, deep Ln above, 
scarcely paler and more or less downy beneath, with 3-5 entire or merely undulate lobes, 
sinus at the base closed at the overlapping lobes: pedicels drooping, pubescent when young : 
calyx UTR emigre: about 5 mm. long : sepals rounded: petals wanting : fruit drooping : 
Samaras em. long, slightly spreading. 
In rich woods or open fields, Ontario to Minnesota, Georgia and Louisiana, Spring. BLACK MAPLE. 
5. Acer Sáccharum Marsh. A forest tree with a maximum height of about 40 m. 
and a trunk diameter of 1.5 m., the wood firm, heavy, the bark usually separating in coarse 
scales at maturity. Leaves appearing with the flowers; blades firm, mostly with 5 sinuate 
toothed lobes, 8-15 em. in diameter, deep green above, pale or glaucous and tomentulose 
at least when young, beneath, cordate with an open shallow sinus: pedicels villous, si 
ing: calyx campanulate, about 5 mm. long: sepals obtuse: petals wanting: disk in the 
