Tuesday, 3 January 2017

Not much of a view from this Atalaya


This not a grass, a sedge or a rush. And it's not a member of some obscure plant family related to those tufted 'monocots'. In fact its a very small tree. Sort of.

Back in late October I spent a few days in Darwin including a steamy day in Litchfield National Park with a bunch of botanic garden bosses, including the head of the George Brown Darwin Botanic Gardens, Bryan Harty. and lead by the local Gardens' seed collector and conservation botanist, Ben Worth.

Through the haze and dripping sweat we saw plenty of fascinating Top End plants. I'll feature a few in coming weeks but I want to start with something very unprepossessing, Atalaya brevialata.

Never heard of it? Neither had I. Atalaya is a city in Argentina, a province in Peru, a castle in South Carolina and a golf club in Spain. Oh, and a plant genus of a dozen or so species in the family Sapindaceae (the soapberry family, including lychees and, these days, maples). 

There are nine species of Atalaya in Australia, all of them found north of Sydney. The others occur in southern Africa and Asian countries to the north of Australia.

'Atalaya' is a Spanish word meaning a tower of some kind, giving an elevated view.  This fits nicely with most descriptions of Atalaya (e.g. PlantNet), which say it's a genus of trees and shrubs - you can see things from trees and larger shrubs. Other genera similarly described are Eucalyptus and Acacia. So that's what you expect, something like a gum tree or a wattle in stature.

But Atalaya brevialata is hardly even a small shrub. The Flora of the Northern Territory describes it's growth habit as suffruticose, which means woody and perennial (that is, long-lived) at the base but predominantly soft and herb-like. So it's a tree or shrub up to, and perhaps just a centimetre or two above, ground level but to all intents and purposes - to you and I - it's grass-like. The above-ground bits are in fact annual - they die back each year (to the 'tree' underground).

So as the top picture shows, it more closely resembles a grass, at least from a distance. It's hard to find in the first place given that it grows among true grasses. Once spotted and you get your eye in it's then hard to miss. Close up you notice, perhaps, that the veins on the leaf are not all parallel like grasses but are net-like and, in relief, lined up in rows at an angle from the mid-rib.


Describing it as a tree or shrub might be technically correct but not very helpful for identification. And we need to find and identify it because it's rare enough to be under threat of extinction. That why Ben has been collecting seed of Atalaya brevialata for the George Brown Darwin Botanic Gardens conservation seed bank, part of the Australian Seed Bank Partnership.


It only grows at and near where we saw it - somewhere near Litchfield National Park. Let's take a closer look at it, by getting down to ground level...


The species name means a short, flattened something, and our plant is rather short, with these flattened leaves. Actually, the name refers to the very short 'wings' on the seed, which are so small I didn't notice them. A bit like the plant itself. .


The flowers are small, fluffy (due to tiny white hairs) and ... well, a cluster of them looks like this: 


These pictures show just a handful of the 300,000 plants of Atalaya brevialata thought to exist in nature, which sounds like a lot. But they live in five small populations, all within a total area of 7-8 square kilometres. So a fire of the wrong kind, land clearing or perhaps a disease could easily wipe out the species, forever. Getting seed into the seed bank is an insurance policy for it's long term future.

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