Tree of heaven

Value to bees

Nectar

Very high

Pollen

Moderate

As a honey crop

Major honey crop — yields a surplus in good years

Which bees, and why

Worked hard by honey bees in the fortnight it is open, and audible from below. The heavy scent that people find unpleasant is precisely what is advertising the flow.

Worth knowing

A heavy urban and post-industrial nectar source, and an uncomfortable one: the same qualities that make it valuable to bees make it a landscape problem.

Flowering

In flower

June to July (northern hemisphere)

A short, heavy, reliable flow in the hottest part of the summer, which is when many Mediterranean landscapes have little else.

When nectar flows

Copious and concentrated in a fortnight. In cities and along disturbed corridors it can be the dominant summer forage.

Year-to-year variation

More reliable than most tree flows because the tree grows where water is available and flowers regardless of a dry spring.

What it does to the honey

Gives a strongly muscat-grape aroma with a faintly medicinal, almost cat-like edge that divides opinion sharply and is unlike anything else in the European catalogue.

Growing it

Conditions

Anything. It grows in pavement cracks, on spoil heaps and through walls, tolerating drought, pollution and compacted soil.

Size

15-25 m, reached remarkably fast.

Native range

Northern and central China. Introduced to Europe in the eighteenth century and now naturalised throughout the Mediterranean, the Balkans, central Europe and North America.

• Do not plant it. This record exists because the honey exists and the tree is already everywhere it is going to be.
• Cutting a stem triggers vigorous suckering from the roots over a wide radius, which is why mechanical removal alone usually makes the problem worse.

What it looks like

Large pinnate leaves up to a metre long with a gland-tipped tooth at the base of each leaflet, and huge terminal panicles of small greenish-yellow flowers. Male trees smell unmistakably and unpleasantly of rancid nuts.