Thursday, 7 December 2017

The Mighty Baobabs

This is another in my periodic series on favourite trees; the most recent one was here, and you can backtrack from there if you're so inclined. I've been wanting to write something on the wonderful baobabs for some time, but was putting it off until I'd met a few more in Madagascar. In the event happenstance and Madagacar Air conspired to rob us of some of the planned trip a few months ago, so I didn't see as many as I'd hoped, but I think there's still enough here to make a post worth while.
Fony Baobab Adansonia rubrostipa, Ifaty Spiny Forest, south-western Madagascar.
Baobabs are a very distinctive genus of nine species found in Madagascar (six), Africa (two) and north-western Australia (one). Until recently they were placed in the family Bombacaceae, but as seems to the way with botanical taxonomy these days, they have now been swept into the huge and unwieldy family Malvaceae (traditionally the home of hibiscuses and mallows). 

The genus name was bestowed by Linnaeus in 1762, to honour French botanist and polymath Michel Adanson, a year after Adanson published the first description of the tree from his explorations in Senegal, where he spent five years collecting everything imaginable, not only plants and animals but trade items, languages and detailed meteorological observations. His family had migrated from Scotland (no idea - weather perhaps?!) and changed the 'm' in their name to an 'n'. He went on to write a two volume Familles des Plantes in which he sought to form all generic names independently of all known languages, including Greek and Latin; it seems to have been too daunting a task however. He also later wanted a coffin garland to represent all his 58 families. Perhaps more significantly his taxonomy was based on what he interpreted as natural relationships, rather than the rather arbitrary arrangements of Linnaeus' early attempts; in this he was ahead of his time, though echoing the suggestions of Robert Ray, a century earlier. He wrote a Natural History of Senegal, but his publisher went broke and Adanson felt obliged to refund those who'd subscribed; this plunged him into a poverty from which he never emerged and he survived only via a small stipend from the French Academy of Sciences. It didn't stop him spending his life on a truly monumental writing project, which basically seems to have comprised everything known about the entire natural world. He offered to the Academy 27 volumes of principles, followed by 150 volumes listing 40,000 species, a dictionary covering 200,000 words (I find this hard to believe, but the 1911 Encyclopaedia Britannica vouches for it!), 40,000 illustrations, and 30,000 specimens of plants, fungi and animals. The Academy declined to publish. It is reported that when the prestigious French Institute invited him to join, he had to decline because he couldn't afford to buy appropriate clothes.

OK, probably time to return to the trees...
Australian Baobab A. gregorii, Gregory NP, Northern Territory.
This species is closest to a group of four of the Madagascan baobabs,
including the three species illustrated in this posting.
It is unclear whether the genus arose in Madagascar, now their stronghold, or on the African mainland. It is a relatively young genus, apparently no more than 10 million years old, so its journey between Madagascar and Africa, and to Australia, must have been achieved by seeds floating across the ocean. More recently humans have transported the widespread African Baobab A. digitata to Madagascar and much of the tropics. It is a greatly valued species, used for food - the fruit, dried or fresh, is prized, and both seeds and young leaves are eaten, timber (including for musical instruments and weapons), fibre and firewood.

A. digitata, Darwin Botanic Gardens.
Recently (2012) a second African species was discovered. Named A. kilima, it is found widely in southern
and eastern Africa, where it sometimes co-exists with A. digitata. The species are very similar, but A. digitatais unique in having twice the chromosome complement of all the other species.

Very old African Baobabs - individual trees have been aged at over 1,000 years - in the Kalahari Desert,
Botswana, above and below. Both these pictures are from old scanned slides.

Indigenous Australians make cords from the root bark fibre of A. gregorii, and eat the sap.
Australian Baobab, Gregory NP.
In Australia the name baobab - which was collected by Adanson in Senegal - is often corrupted to 'boab'. 'Bottle tree' is also sometimes used, but this is a confusion with Queensland members of the unrelated genus Brachychiton.

Za Baobab A. za, Ifaty Spiny Forest.
I can't find a reference to the name, but I assume it is a Malagasy word for the tree.
In all the species above, the form of the tree is distinctive. They are 'pachycauls', with thick trunks relative to their height, and few branches, mostly sprouting from the top. They are said to be able to store up to 100,000 litres of water in their trunk (in tissue, not a big internal tank!) to last them between wet seasons. All are deciduous, to assist in water conservation.

Perhaps we could end by just enjoying a few more portraits of these magnificent trees.
Madagascar Baobab A. madagascarensis, Ankarana NP, northern Madagascar.
This is a limestone national park, and this species is closely associated with that rock.

Fony Baobab, Ifaty Spiny Forest.
Za Baobab, Ifaty Spiny Forest.
Sakalava Weaver nests, Ifaty village, south-western Madagascar.
Australian Baobabs, Gregory NP.
In a diary entry from my first trip to the east Kimberley, where I first saw these wonderful trees,
I wrote of the "magnificently grotesque Baobabs.... great corpulent patriarchs, with twisted swollen arthritic limbs".
Hopelessly anthropomorphic, I readily acknowledge. But baobabs tend to have that effect on me, I'm afraid. I love them.

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Flabmeister said...

In Tanzania they are sometimes called "the trees that grow upside down". This obviously refers to the way the branches, when leafless, look like roots!

David Nash said...

Za does indeed seem to be the Malagasy word for baobab: citing Hallanger 1973.

Ian Fraser said...

Thanks Martin; I'd meant to say that, as 'baobab' is apparently from a West African tongue, of course there are different names for the trees elsewhere in Africa. I've heard that this phrase is also used in one or more of the Kimberley languages, and it's even been proposed that this is proof that people brought baobabs to Australia!!

Many thanks David - I should have thought just to go to you about it in the first place!

David Nash said...

Thanks Ian. On the distribution, there's a 2015 paper 'New genetic and linguistic analyses show ancient human influence on baobab evolution and distribution in Australia'

Ian Fraser said...

Thanks for that link David, it's one I didn't know about and I'm not at all surprised by it. Of course it's a very different proposition from the one that humans brought the species to Australia at least several hundred thousand years ago, from Madagascar where the closest relations to the Australian species seem to be (I omitted that, inadvertently, from the post).