Catalpa bignonioides

Few trees capture attention quite like the Catalpa.

With their bold heart-shaped leaves, striking summer flowers, and elegant forms, these trees bring a lush, architectural charm to any garden.

Two forms are particularly beloved among gardeners and landscapers, the standard Catalpa bignonioides and its compact cousin, the Catalpa bignonioides ‘Nana’, better known as the Designer Mop Top.

While they share the same heritage, these two Catalpas couldn’t be more different in personality, one is a grand shade provider, the other a sculptural showpiece.

Let’s explore both in detail below.

The Catalpa bignonioides, or Indian Bean Tree, is a deciduous ornamental tree known for its large, tropical-style leaves and showy clusters of white, trumpet-shaped flowers that bloom through summer.

Growing between 8 to 12 metres tall and spreading 6 to 10 metres wide, it forms a broad, symmetrical canopy of large, heart-shaped green leaves that provide dense shade throughout summer.

In early to mid-summer, it bursts into clusters of creamy white, trumpet-shaped flowers with delicate purple and yellow markings, creating a showy display against the lush green foliage.

As the season progresses, the tree develops long, bean-like seed pods that hang decoratively through winter, adding interest even after the leaves

Now meet the Designer Mop Top, a dwarf grafted form of the Catalpa. Officially known as Catalpa bignonioides ‘Nana’, this variety has become a modern landscaping favourite for its compact size and perfectly rounded canopy.

Where the standard Catalpa towers over lawns, the Nana offers elegant restraint, the same lush foliage, but in a sculptural, space-saving form.

The Designer Mop Top, typically grows to around 2–3 metres in height with a spread of 2–4 metres. It forms a dense, rounded crown of large, lime-green leaves, creating a striking globe-shaped canopy that brings an instant sense of balance and symmetry to any landscape.

Unlike its larger relative, the standard Catalpa, the Nana variety rarely produces flowers or pods, focusing instead on its sculptural, leafy form.

⚖️ Side-by-Side Comparison

Feature	Catalpa bignonioides (Standard)	Catalpa bignonioides ‘Nana’ (Designer Mop Top)
Height	8–12 m	2–3 m
Width	6–10 m	2–4 m
Growth Rate	Moderate to fast	Moderate
Flowers	Large white clusters in summer	Rarely flowers
Foliage	Large heart-shaped green leaves	Same foliage, denser canopy
Form	Broad spreading tree	Compact, rounded canopy
Use	Shade, feature, avenue	Sculptural, formal, small spaces
Maintenance	Minimal pruning	Light trimming to shape
Root System	Deep and spreading	Non-invasive, grafted form
Best For	Parks, large gardens	Courtyards, driveways, modern landscapes