Acer griseum: Paperbark Maple

Friday, March 21 2003 @ 03:13 AM

Contributed by: Admin

Source:nobleplants.com
FAMILY: Aceraceae

LEAVES:
Opposite, trifoliate, 3 to 6' long, each leaflet elliptic to ovate-oblong, 2 to 2 1/2" long, half as wide, apex acute, base cuneate, middle leaflet short-stalked, coarsely toothed; lateral leaflets almost sessile, not as toothed, lower surface distinctly pubescent especially on the veins, dark bluish green above, pale green to glaucous beneath; petioleā??distinctly pubescent, 2 to 3" long.

BUDS: Imbricate, brownish black, 1/8 to 1/4" long, sharply pointed, reminiscent of Sugar Maple buds except for size and color; distinctly pubescent at base of bud, almost a collar of hairs surrounds the terminals and laterals.

STEM: Fine branches, pubescent at first, rich brown; stems develop exfoliating character during their second and third year which becomes more pronounced with age; bark color varies but is usually a cinnamon brown; leaf scars are surrounded by tufts of hairs; pithā??white, solid, becoming brown on older stems.

Size: 20 to 30' in height; spread one-half or equal to height; can reach 40 to 50' but usually smaller under cultivation.

HABIT: Upright-oval, oval or rounded; usually favoring the latter two descriptions; the splendid specimens on the University of Illinois campus are extremely variable but tend toward the oval-rounded habit; the specimens at the Arnold Arboretum offer age and, with age, Acer griseum assumes a dignity unmatched by other trees; a trip to view the Arnoldā??s magnificent specimens is justified in any season; the oldest specimen in the United States exists in the Arnold Arboretum (91 years as of this publication date); specimens in Europe tend to be rounded to broad spreading.

BARK: Young stems rich brown to reddish brown; older wood (1/2" diameter or greater) a beautiful cinnamon or red-brown as the bark exfoliates to expose these colors; second year wood usually starts to exfoliate, thus the exquisite bark character develops at a very young age; old trunks lose some of the exfoliating character but retain the rich brown colors; significant variation in degree of flakiness, and if a young tree does not exhibit a striking exfoliating character, this will carry into maturity; verbal descriptions cannot do justice to this ornamental asset and only after one has been privileged to view the bark firsthand can he or she fully appreciate the character; snow acts as a perfect foil for the bark and accentuates its qualities.

LEAF COLOR: Flat dark to bluish green in summer changing to bronze, russet-red or red in fall; fall color can be spectacular but in seven years at Illinois I never once witnessed anything but muted green-red-brown colors; however, while on sabbatical leave at the Arnold Arboretum I was fortunate enough to have seen spectacular red coloration; in Georgia fall color is a muted red; Acer griseum is the last of the trifoliate maples [A. mandshuricum, A. maximowiczianum (A. nikoense), A. triflorum] to color and may hold some leaves into early November as far north as Boston.

FLOWERS: Few or solitary, greenish, on pendulous, 1" long, pubescent peduncles.

FRUIT: Samara, 1 to 1 1/2" long, pubescent, woody nutlet, wings diverge at a 60 to 90Ā° angle.

http://www.mygardenpatch.com/20030321031340138.htm

LEAVES:	Opposite, trifoliate, 3 to 6' long, each leaflet elliptic to ovate-oblong, 2 to 2 1/2" long, half as wide, apex acute, base cuneate, middle leaflet short-stalked, coarsely toothed; lateral leaflets almost sessile, not as toothed, lower surface distinctly pubescent especially on the veins, dark bluish green above, pale green to glaucous beneath; petioleā??distinctly pubescent, 2 to 3" long.
BUDS:	Imbricate, brownish black, 1/8 to 1/4" long, sharply pointed, reminiscent of Sugar Maple buds except for size and color; distinctly pubescent at base of bud, almost a collar of hairs surrounds the terminals and laterals.
STEM:	Fine branches, pubescent at first, rich brown; stems develop exfoliating character during their second and third year which becomes more pronounced with age; bark color varies but is usually a cinnamon brown; leaf scars are surrounded by tufts of hairs; pithā??white, solid, becoming brown on older stems.
Size:	20 to 30' in height; spread one-half or equal to height; can reach 40 to 50' but usually smaller under cultivation.
HABIT:	Upright-oval, oval or rounded; usually favoring the latter two descriptions; the splendid specimens on the University of Illinois campus are extremely variable but tend toward the oval-rounded habit; the specimens at the Arnold Arboretum offer age and, with age, Acer griseum assumes a dignity unmatched by other trees; a trip to view the Arnoldā??s magnificent specimens is justified in any season; the oldest specimen in the United States exists in the Arnold Arboretum (91 years as of this publication date); specimens in Europe tend to be rounded to broad spreading.
BARK:	Young stems rich brown to reddish brown; older wood (1/2" diameter or greater) a beautiful cinnamon or red-brown as the bark exfoliates to expose these colors; second year wood usually starts to exfoliate, thus the exquisite bark character develops at a very young age; old trunks lose some of the exfoliating character but retain the rich brown colors; significant variation in degree of flakiness, and if a young tree does not exhibit a striking exfoliating character, this will carry into maturity; verbal descriptions cannot do justice to this ornamental asset and only after one has been privileged to view the bark firsthand can he or she fully appreciate the character; snow acts as a perfect foil for the bark and accentuates its qualities.
LEAF COLOR:	Flat dark to bluish green in summer changing to bronze, russet-red or red in fall; fall color can be spectacular but in seven years at Illinois I never once witnessed anything but muted green-red-brown colors; however, while on sabbatical leave at the Arnold Arboretum I was fortunate enough to have seen spectacular red coloration; in Georgia fall color is a muted red; Acer griseum is the last of the trifoliate maples [A. mandshuricum, A. maximowiczianum (A. nikoense), A. triflorum] to color and may hold some leaves into early November as far north as Boston.
FLOWERS:	Few or solitary, greenish, on pendulous, 1" long, pubescent peduncles.
FRUIT:	Samara, 1 to 1 1/2" long, pubescent, woody nutlet, wings diverge at a 60 to 90Ā° angle.