The inflorescence of solidago gigantea
is typically large, containing up to 600 small yellow flowerheads in a layered, pyramidal cluster, with some gaps between the component stalks. Flowerheads may be subtended by two small, linear bracts. The yellowish-green phyllaries are in three to four rows, enclosing the short, bell-shaped involucre. Above are between 9 and 15 ray florets around a center of 7 to 12 disc florets.
Phyllaries, leaves and stems are generally hairless, though the veins on the underside of the leaves may be slightly hairy. Stems are light green to greyish in color, or glaucous. Leaves grow only along the stem, and are largest around the middle. They have a midvein, a faint pair of side veins branching at the base, and another pair branching higher up. Leaf edges are lined with sharp teeth.