Willow dock is our common native dock, a perennial with branched stems that is usually in seasonally moist habitats.  In most populations, the 3-angled fruiting structure (= achene + inner tepals) has 3 prominent swollen “grains”; i.e., one on each of the inner tepals.  However, in a few populations (e.g., Lydle Gulch), there is only a single “grain”, on the outward-facing tepal.  This latter variant keyed to var. salicifolius in some previous treatments, but it now fits within an expanded definition of var. triangulivalvis, as the only variety known to occur in our area.