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• Leaf size and shape. Note the flat or slightly folded, narrower leaves of H. drummondii. Leaves of the other taxa are broader, often with a somewhat 'cupped' lamina, at times with visible pinnate secondary veins.

  H. drummondii	H. drummondii	H. reverchonii var. reverchonii

  H. reverchonii var. reverchonii	H. reverchonii var. serpyllifolia	H. reverchonii var. serpyllifolia

• Calyx lobes. The upper 3 lobes of H. drummondii clasp the corolla tube. With the other taxa these are spreading away from the tube, somewhat reflexed.

  H. drummondii	H. drummondii

  H. reverchonii var. reverchonii	H. reverchonii var. reverchonii

  H. reverchonii var. serpyllifolia	H. reverchonii var. serpyllifolia

• Winter leaves. Specimens of all 3 taxa exhibited the development of distinct fall/winter leaves at the base, heavily pubescent in contrast with the normal leaves. Those of H. drummondii were narrowly oblong, and lacked any trace of secondary venation. With the other taxa these were much rounder than the normal leaves and commonly revealed secondary pinnate venation, H. reverchonii var. reverchonii appeared to have the strongest venation.

  H. drummondii	H. drummondii

  H. reverchonii var. reverchonii	H. reverchonii var. reverchonii

  H. reverchonii var. serpyllifolia	H. reverchonii var. serpyllifolia