Sand Dock (Rumex venosus)

I think I'm right in identifying this plant as Wild Begonia/Sand Dock/Veined Dock (Rumex venosus). It is found along roadsides, dry soil and sand dunes. We wondered what this plant was when we first saw it on our way to Purple Spring Sand Dunes, near Taber, yesterday. It gave such a wonderful colour to the roadsides.

"During the fruiting phase, this species resembles a begonia, hence the common name. Wild Begonia is often one of the first plants to establish itself on active sand dunes. The tender young shoots were used as a rhubarb or spinach replacement by early pioneers. The Blackfoot made a burnt orange dye from the peeled roots." From "Plants of Alberta" by France Royer and Richard Dickinson (Lone Pine publication).