🏛️ Exclamation London Planetree

Platanus × acerifolia ‘Morton Circle’ (Exclamation!)
The upright planetree with the punctuation to match: uniform, pyramidal, anthracnose-resistant shade for streets that need a clean line.
Sun
Full sun
Mature size
About 50–60 ft tall, 30–45 ft wide; upright, pyramidal habit
Spacing
40–50 ft from other large trees and structures
Soil pH
Wide tolerance; prefers moist, well-drained soil but tolerates poor soils
Zones
Zones 4–8; North Florida at best, marginal in Florida

What it looks like

Exclamation London Planetree (Platanus ×) — CBG Parking Lot 1 - Platanus x acerifolia 'Morton Circle' Exclamation! 150627
CBG Parking Lot 1 – Platanus x acerifolia ‘Morton Circle’ Exclamation! 150627. Photo: cultivar413 from Fallbrook, California, CC BY 2.0.
Exclamation London Planetree (Platanus ×) — CBG Parking Lot 1 - Platanus x acerifolia 'Morton Circle' Exclamation! apparently not sheared 150627
CBG Parking Lot 1 – Platanus x acerifolia ‘Morton Circle’ Exclamation! apparently not sheared 150627. Photo: cultivar413 from Fallbrook, California, CC BY 2.0.
Exclamation London Planetree (Platanus ×) — CBG Parking Lot 1 - Platanus x acerifolia 'Morton Circle' Exclamation! label 150627
CBG Parking Lot 1 – Platanus x acerifolia ‘Morton Circle’ Exclamation! label 150627. Photo: cultivar413 from Fallbrook, California, CC BY 2.0.

Why this variety

Exclamation! — botanically ‘Morton Circle’, introduced by Chicagoland Grows — is the London planetree for streets and avenues that need uniformity: a more uniform, upright, pyramidal tree than the species, growing 50 to 60 feet tall and 30 to 45 feet wide, with a strong central leader, densely branched crown, and the family’s mottled peeling bark. The Morton Arboretum credits it with resistance to anthracnose and frost cracking, and tolerance of pollution, drought, poor drainage, and compacted soils — a resume that reads like a city tree’s job application, approved.

The exclamation mark is marketing, but the uniformity is real: planted in a row, Exclamation trees line up like soldiers instead of sprawling like the species, which is why avenues and campuses choose it. It is still a large tree with large-tree roots and litter, and the Florida caution still holds — temperate-zone tree, marginal at best in North Florida. Where it belongs, though, it is the tidiest big planetree available, and the one least likely to embarrass a streetscape.

If you have not met the species yet, start with the London Planetree guide for the whole hybrid, then come back here for Exclamation in detail.

How to grow

Plant Exclamation in spring or fall in full sun in moist, deep, well-drained soil — it tolerates poorer soils and compaction better than most trees its size — with 40 to 50 feet of clearance. Water deeply until established, mulch widely, and prune in late fall or winter to keep the strong central leader dominant; the upright pyramidal form is the selling point, so remove competing leaders while young rather than letting the tree fork into a sprawl. Its tolerance of poor drainage is a bonus, not a license to plant it in a swamp.

Water & feeding

Water deeply until established, then through droughts; Exclamation tolerates drought and poor drainage once established, but steady moisture gives the fastest, cleanest growth. Compost at planting and mulch beat heavy fertilizer, and a vigorous tree shows its anthracnose resistance best.

Common problems

  • Anthracnose in wet springs — resisted, not eliminated; airflow and cleanup still matter.
  • Canker stain and lace bug — the planetree watch list, unchanged.
  • Frost cracking — resisted better than most planetrees, but young bark still benefits from a sheltered site in the coldest zones.
  • Competing leaders — remove early, or the upright form becomes a forked one.

Harvest

The harvest is a clean line: uniform upright shade, mottled bark, yellow fall leaves, and an avenue that looks planted on purpose. Exclamation is the planetree for the street that must read as a design, not an accident.

Nerdy fact: The ‘Morton Circle’ name comes from the Morton Arboretum’s Chicagoland Grows program, which selects and introduces trees proven in Midwestern street conditions — Exclamation passed trials for cold, pollution, and compaction before it ever earned its punctuation. The exclamation mark is the least exaggerated part.

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Saving seeds

Exclamation! — botanically ‘Morton Circle’ — is a uniform, upright London planetree selection, and it is grown as a nursery tree — seedlings won’t hold its pyramidal form or strong central leader. The Propagation section of the London Planetree guide covers the route.