Tuesday, 15 March 2011

The Ombú



One of the most imposing trees in the Royal Botanic Gardens is the Ombú. It’s not the tallest (that’s a Kauri Pine in the Palm Grove at 33m) and it’s not the rarest (that’s a tussle between the Wollemi Pine, Maiden’s Palm, the Nightcap Oak, and a eucalypt or two).

What’s impressive about the Ombú is its swollen base. It doesn’t have the rippling buttresses of some other tropical trees, or the strangling limbs of a fig, but it looks like it is connected to the very crust of the earth. It seems to rise like a volcano from the ground below.

Although it looks like a typical tree, albeit a bit broad at the base, its trunk is unusually fleshy and mostly water. It’s sometimes called the Tree Pokeweed because it’s in the same genus as the weedy herb called Pokeweed from North America, and more like a pumped-up herb than a tree.

Botanically called Phytolacca dioica, its local name in South America is the more sonorous Ombú. It also has another Spanish name, Bella Sombra, meaning ‘beautiful shade’. On the pampas plains of Argentina and Uruguay, it is the only large tree.

We have two Ombú in the Royal Botanic Gardens. One large tree in the formal garden beds near the original site of the first farm and botanic garden, planted by Alan Correy in 1955, and a smaller specimen in the Cacti and Succulent Garden.

As the species name suggests (from 'dioecious'), some plants have male flowers, others female. The larger tree is a boy. The flowers are small, but there lots of them produced in late October to November.

Ombú is drought and fire tolerant, and a fun tree to plant in Sydney. Just be careful of the sap which is poisonous to animals (including us!).

Image: The base of the large Ombú in Sydney's Royal Botanic Gardens. *This posting is from the Radio Archives (November 2008).

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