We are said to have H. heterophylla and H. linearis in this area, though I have only observed the former. The specimen is not this species. The stems are fairly thick (I had wondered whether I should try it as a shrub rather than herb), much thicker than those of H. heterophylla. Our local H. heterophylla have leaves about 15mm long and narrow, this specimen has leaves about 25mm long and comparatively wide.