...but the leaves, I think, are too ovate, not lanceolate enough. Also, the multiple stems originating at the base are suspicious. It's a single plant, about 1m high, sprawling over about 1.3m. And if it is A. retroflexus, has anyone ever bothered to keep it around and try to collect and use the seeds?
Not sure, but that sounds like the correct plant. E-Flora BC has good info and pics to compare. I have not saved the seed from it, but have eaten the leaves. (Your plant is too mature for that now.) PFAF indicates the seed can be eaten. And this is interesting. Amaranth: Grain, Vegetable, Icon - Eat The Weeds and other things, too
