I'm pretty sure these are a Stachys species - the third largest genus of the Labiatae after Salvia and Scutellaria. Note the four stamens in the flower at position 4:30 on the spike in the lower image. It looks a lot like some of the California species, many of which are stoloniferous (bearing runners). Stachys floridus of Florida is a nursery and garden pest.

I also think that this may be not a Salvia, but beautiful pictures nevertheless.

Regards, Robin.

Thanks so much. Labiatae is not a family I know much about, but I do find it interesting. These plants do seem to be fairly aggressive/successful as it can be seen throughout the area on either side of the stream. Perhaps they do increase by stolons. I'll have a closer look next time.

I'm almost certain it's Stachys riederi var. japonica. Apparently it is used for medicinal purposes in East Asia. An interesting plant, probably hardy to zone 4 at least. Thanks again for the help.

Regards,
Joseph

Here is a link that might be useful: Stachys riederi