Solidago gigantea develops clones of stems often 1 meter
tall or more (50-200+ cm) with conspicuous, roughly
triangular inflorescences of many small, bright yellow flowers
in heads. The flower heads are secund,
meaning that the pedicels by which they are attached tend to bend
around the branch so that all or most heads appear to arise from
the top of the branch. The leaves are simple and alternate, 6-18
cm long and about 1/4 as wide and tapering to both ends. The leaf
margins are sharply toothed, at least in the distal half, and
the leaves generally have two larger lateral veins that, together
with the midrib, give them a conspicuous 3-nerved
Solidago gigantea is similar in general form to S.
canadensis and S. altissima and two or more of these
species may occur in close proximity to one another. S. gigantea
can be distinguished from the other two species by its glabrous
and (often) glaucus stem below the inflorescence (the upper
part of the stem, as it becomes the axis of the inflorescence,
is usually pubescent, however). The stem in the other two species
is pubescent below the inflorescence (though not necessarily all
the way to the base).
Beginners are advised to read the identification
of goldenrod species.