EPOW - Ecology Picture of the Week

Giant Rhubarb or Chilean Gunnera (Gunnera tinctoria)
Family Gunneraceae
Andes Mountains, southern Chile

Explanation:   What an interesting plant.  I encountered this monster along a disturbed roadside at a high elevation pass in the Andes Mountains of southern Chile just over the border from Argentina.  Its leaves are 1-2 m (3-6 ft) wide and its flowering spikes reached a good 1 m (3 ft) high.  

Variously called giant rhubarb, Chilean gunnera, nalca, panque, and other names, this is actually a huge perennial herb, not a shrub.  But it grows in clumps in disturbed locations and can shade out native vegetation.   It has spines on the stems.  Each seed head can contain more than 80,000 seeds which are often dispersed by birds.  And a single plant, with all of its multiple seed heads, can produce a quarter of a million seeds in a single year!  

 Giant rhubarb herbs growing in a clump along a roadcut
over the Andes Mountains of southern Chile.

In its native environment, here in Chile, it seems to exist with many other plant species, but elsewhere -- in forests, wetlands, streamsides, and along coastlines -- it is treated as an invasive exotic needing intense control measures.  Still, it is sold as a cultivare.

The plant has some positive uses, though, as the young leaf stalks can be eaten raw or cooked ... it has medicinal uses as an astringent ... and a black dye can be made from the root.  

There is a remarkable symbiosis going on within the stems.  Nitrogen-fixing cyanobacteria of genus Nostoc occur within its cells.