Leucaena

How to identify a leucaena

The leaves are fern-like and twice divided, up to about 35 cm long, with 3 to 10 pairs of side branches, each lined with many small, pointed grey-green leaflets 7 to 21 mm long. A small raised gland sits on the leaf stalk. Round, fluffy cream pompoms 1 to 3 cm across appear mostly in summer, followed by dense bunches of flat pods 8 to 22 cm long that ripen brown. Young stems are finely hairy, and older bark is smooth and grey with small raised spots. Brisbane City Council notes that a plant suspected to be the uncommon white ball acacia is more likely to be leucaena; white ball acacia has much smaller leaflets and shorter pods.

Growing a leucaena in Brisbane

Leucaena is widely naturalised around south-east Queensland, and Brisbane City Council describes it as a serious problem along creeks and roadsides. It also turns up in gardens, parks, waste ground and on coastal foreshores. A single plant can drop thousands of seeds a year, which birds, possums, rodents, wind and water spread around, and it regrows after cutting. The result is dense thickets that crowd out native plants, block wildlife and reduce visibility along roads.

What to watch out for

It's treated as a weed in Brisbane, but there's no legal requirement attached to it. It seeds heavily and resprouts after cutting, so plan on follow-up after removal. Livestock that eat the foliage, seeds or pods can be poisoned, which matters on acreage with horses. Take care when lopping it near power lines.

• Poisonous parts. Livestock that eat its foliage, seeds or pods can be poisoned; horses can suffer weight loss, laminitis, mouth sores and hair loss.
• Seedlings. It sets huge numbers of seeds that birds, rodents, wind and water carry away, and it resprouts after being cut.

Pruning and care

There's no reason to prune leucaena for shape; the aim is control. Hand-pull seedlings and small plants, making sure the roots come out so they can't regrow. For established plants, Brisbane City Council lists cut stump, basal bark and stem injection treatments. Because it seeds so heavily, plan on follow-up visits to catch new seedlings. Business Queensland warns to take care when trimming or lopping it near power lines, which is a job for a professional with the right gear.

• Tree removal
• Stump grinding