#brasilian giant rubharb

[regnum-plantae]

Gunnera manicata, Gunneraceae

There is literally no chance you could walk by Brasilian giant rhubarb and miss it, with its huge leaves often growing up to and in excess of 2 metres wide, held up on large, fleshy petioles 2.5 metres tall. It’s simply the most imposing herbaceous dicot you could encounter thriving in a temperate climate area, and for this reason it is often used as a dramatic backdrop to a pond here in the UK, as you can see in these photos. It instantly gives that Jurassic tropical feeling. 

Unfortunately, there’s seems to be a lot of confusion online and in garden centres about the distinction between G. manicata and G. tinctoria, its slightly smaller Chilean counterpart: the best way to tell them apart, especially when young, is by looking at the large inflorescence and seed head. In the middle photo you can see an up-close of the branched, green panicle typical of G. manicata, while G. tinctoria bears a more compact reddish one.

It’s worth nothing that both species were introduced in the British Isles in the mid XX century and were already recorded growing in the wild in the first few decades of the XXI, but while G. manicata doesn’t seem likely to become invasive, G. tinctoria has the potential to do so, and is already listed as an invasive weed in Ireland. 

Rapid water seed dispersal and their symbiotic relationship with nitrogen-fixing cyanobacteria, unique among angiosperms, certainly give them an advantage at becoming established in riparian ecosystems, where their sheer size and extensive root network is enough to displace native species and alter their distribution. This said, I still haven’t seen any of the two growing wild here in Scotland, although they have both been reported in several sites.  

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