Plant ID for small herb in Mission, BC

This plant was found near a small stream at low elevation on a site with high disturbance. Its undersides are reddish. We're doing vegetation plots and any help would be greatly appreciated!

 

Epilobium sp., perhaps?

 

I would lean more toward Impatiens parviflora, though I wouldn't rule out Epilobium (how juicy-crispy are the stems -- do they snap when bent?)

 

Thanks very much for the suggestion but I don't think they're policeman's helmet (though there is some on the site). The leaves are thick and it looks more perennial. I'm not there right now so I can't test whether they would snap but they were so thick that I think they probably would. They had a definite purple underneath. Here's another shot we took of it.

 

One of the common weedy, ephemeral fire-weeds such as are seen by the thousands in plant containers and moist cultivated beds.

 

Thanks for the additional photo, a better sense of scale. Yes, concur with Epilobium now. (policeman's helmet is Impatiens glandulifera, by the way)

 

Great, thanks so much both of you :)