<i>Platanus x acerifolia</i> 'Morton Circle' Exclamation!

The exfoliating bark appears at a young age. Photo courtsey of Chicagoland Grows.Platanus × acerifolia ‘Morton Circle’ Exclamation! is an interspecific hybrid from George Ware at The Morton Arboretum in Lisle, Ill. Ware crossed P. orientalis (a naturally anthracnose-resistant species from the U.S. National Arboretum) with an anthracnose-resistant P. occidentalis growing at The Morton Arboretum. The original plant of Exclamation! has been observed since 1994.

Ware selected Exclamation! for its uniform, upright pyramidal habit, which is conical in its youth. It also offers a strong central leader with dense branching.

Medium green, deeply palmate-lobed foliage cloaks the tree all summer with an occasional brief display of yellow in the fall. It’s light fruiting as a young tree. Older specimens exhibit less fruiting than other planetrees in the market.

The exfoliating bark is the London planetree’s most interesting characteristic, and Exclamation! is no exception. The mottled brown, green and tan bark peels off in large plates revealing patches of interior bark in varying shades of cream to white.

Strong urbanite
Besides anthracnose resistance, Exclamation! also shows resistance to frost cracking. It also has good resistance to powdery mildew, which, if present, occurs in late summer to early fall.

SPECIFICS

Name: Platanus × acerifolia ‘Morton Circle’ Exclamation! Description: Uniform, upright pyramidal habit. It also offers a strong central leader with dense branching. Medium green, deeply palmate-lobed foliage cloaks the tree all summer. Develops attractive, exfoliating bark at a young age. Size: 60 feet tall by 45 feet wide at maturity. Landscape uses: In large parking lot islands, median strip plantings, as a residential street tree or as a shade tree. Hardiness: USDA Hardiness Zones 4-8. Propagation: Softwood cuttings. Clonal propagation is required, as plants propagated from seed will not be true to type.

It’s adaptable to a wide range of soils but grows best in full sun with good air circulation. It’s easy to grow and long-lived. It’s tolerant of poor soils, extended flooding or drought and air pollution.

It’s hardy in USDA Hardiness Zones 4-8.

Exclamation! features superior adaptability, hardiness, disease resistance, and upright, dense habit, which lends itself to a multitude of landscape applications.

It works well in large parking lot islands, median strip plantings, as a residential street tree or as a shade tree. London planetrees are noted for excellent tolerance to difficult urban conditions.

Exclamation! is a good replacement for ash.

At maturity, Exclamation! will likely grow to 60 feet tall by 45 feet wide.

As a young specimen, it grows fast — up to 3 feet per year, then slows a bit to a moderate grower — about 1 to 1½ feet per year until maturity.

It’s easily propagated through softwood cuttings. Clonal propagation is required, as plants propagated from seed will not be true to type.

Exclamation! was introduced by Chicagoland Grows from the tree breeding program at The Morton Arboretum. It’s a sister seedling to Ovation, another London planetree introduced by Chicagoland Grows.

– Chicagoland Grows, www.chicagolandgrows.org