How can I differentiate between Albizia (Mimosa, Silk Tree) and Delonix regia (Flamboyant) when the plant is young?

I live in Maui, where Albizia is an invasive species responsible for monocultures, loss of habitat, build and road damage, and even falling and killing people. I want to be aggressive about removing it from my property. It's also much easier to kill when it's young.

However, I also have a Delonix regia (Flamboyant) growing in my backyard which looks similar except for its flowers.

Flowers of Falcataria moluccana Flowers of Delonix regia

How can I differentiate between the two when they're young so I can kill the Albizia but not the Delonix regia?

Update: I've recently learned that there are two different species (genuses, actually!) called Albizia here in Maui: Albizia julibrissin and Falcataria moluccana. I also don't know how to differentiate these, but they're both invasive, so I want to weed out both. It seems Falcataria moluccana is more common.

  • Albicia is considered invasive in general, in most parts of the world. – Aleksandar M Jun 15 '19 at 4:54

It's an interesting challenge. Even for taxonomists the differentiation of some species in the same genus is taxing, and the pea family is quite leguminous for this. Since the only reliable way to separate them practically is by letting them flower - by which time it is too late - what we need in the immediate term is a strategy.

Let's assume that you have mature examples of both Delonix and Albizia. One strategy would be to eliminate all immature plants that could be either species, but leaving in place all those you are convinced are Delonix due to age or other factors. Propagate more of the desired species from seed or cuttings from the mature plants. Cuttings will give you exactly the same tree back, which may be desirable, and the seeds will give some variety which may be even more desirable.

Designate a nursery area where young desirable plants are raised and cannot be invaded by Albizia. Mark the young plants, perhaps with a stripe of known paint colour or by recording GPS coordinates once planted out, and keep this flash clear and visible until they mature to flower. Choose a paint colour that mischievous people cannot paint Albizia with.

Of course, you are the best judge of whether this is a workable strategy in your situation.

  • While I'm disappointed that there's not an easy answer, I appreciate all the work that it takes to differentiate certain species. – Merchako Jun 19 '19 at 18:55

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