Acacia …

And whilst we are in Pian Upe, sheltering from the rain and contemplating the names of things. What was the first Acacia ever described? While you’re thinking about that let me introduce you to the Whistling Thorn. It is common in Pian Upe.

Whistling Thorn Vachellia drepanolobium

Otherwise known as Vachellia drepanolobium and an excellent example of a myrmecophyte. That swelling is provided by the plant as housing for the ants you see in the photo. They in turn provide the plant with some protection from browsing herbivores, creatures that have evolved to disregard those spines. Symbiosis between ants and plants has arisen in several groups of plants throughout the tropics and often involves the provision of nectar as ant food as well as living spaces or domatia.

The first Acacia formally described was Acacia nilotica Linnaeus 1773 although the name Acacia was borrowed from an English gardener Phillip Miller who’d used it in 1754. He had borrowed it from Pedanius Dioscorides who had used  the Greek word for thorny ἀκακία (akakia) to describe a tree with medicinal uses in his book Materia Medica dating from the first century AD. Because it was the first described the African nilotica became the type species of the genus Acacia.

Acacias were subsequently described throughout the tropics, in South America and in Australia where it has become the national floral emblem …

Here is the wattle

Emblem of our land

you can stick it in a bottle

or hold it in you hand … Monty Python (Bruce’s sketch).

In fact the genus got to about 1,400 species worth. Science being a tireless quest for an ever more complicated way of simplifying stuff found that there were three groups or subgenera included and it was proposed that the genus be split. Since Acacia was first described in Africa it would be supposed that Africa would hang on to that particular name. The Australians fell sobbing on the ground, “You can’t do that to our national emblem”, they cried.

And so it came to pass that Africa has had to learn a couple of new genus names. The thorny Acacias of Africa, like the myrmacophytic drepanolobium have become Vachellia while thorn deficient ones have become Senegalia. The South Americans formerly known as Acacia are likely to end up in two entirely new genera neither of them named Princia.

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