stiff goldenrod

Stiff goldenrod (ssp.humilis) is a 10″ to 27″ tall, erect, perennial forb that rises on 1 to 10 stems from a short, branched, woody caudex.

The stems are erect or ascending, stout, and unbranched below the inflorescence. They are rough to the touch due to a moderate to dense covering of short, stiff, curved hairs, even near the base. At the base of the stem is a rosette of basal leaves which is usually present when the plant is in flower. There may be additional rosettes of leaves adjacent to the stem.

Basal leaves are small, egg-shaped, inversely egg-shaped, or oblong-elliptic, up to 4¾″ long, and up to 2″ wide, 3 to 6 times as long as wide. They are firm and flat. They stand somewhat erect on leaf stalks that are often as long or longer than the blade. The upper and lower surfaces are somewhat rough to the touch due to a moderate to dense covering of short, fine, curved hairs. On the underside there is a single, prominent midvein. The margins are untoothed or may have fine, rounded teeth. Lower stem leaves are similar but smaller and on shorter leaf stalks.

Middle stem leaves are stalkless, thick, fleshy, rigid, egg-shaped, 1¼″ to 2″ long, about ⅝″ wide, and otherwise similar to the basal leaves. They become progressively smaller as they ascend the stem. The margins of at least the upper stem leaves are untoothed.

The inflorescence is is a tightly clumped, usually rounded, corymb-like array of 9 to 190 flower heads at the end of the stem. It is usually 1¼″ to 8″ long and 2½″ to 7″ wide, but it can be larger.

The tiny flower heads are large relative to other goldenrods, the disk 3 ⁄16″ to ⅜″ wide. They have 6 to 14, usually 7 to 10, yellow ray florets and 14 to 35, usually 20 to 30, yellow disk florets.

The fruit is an achene with some short, loose hairs near the tip.

10″ to 27″

Yellow ray florets, yellow disk florets

Stiff goldenrod (Solidago rigida ssp. rigida) is a larger plant, 24″ to 60″ in height. The basal leaves are larger, up to 10″ long by 4″ wide. The inflorescence is loose, open, spreading, flat-topped, and larger, up to 8″ long and 7″ wide. The achene has no hairs near the tip.

Dry to moderate moisture. Tall-grass and mixed-grass prairies, open woods, roadsides, disturbed sites, open fields. Full sun to partial shade. Sandy or loamy soil.

August to October

Sources

4, 7, 29, 30.

Native

Some taxonomist separate the seven flat-topped goldenrod species in the Solidago section Ptarmicoidei as a separate genus Oligoneuron. The Global Compositae Database lists stiff goldenrod as Oligoneuron rigidum, with Solidago rigida a synonym. The Global Compositae Checklist lists it as Solidago rigida, with Oligoneuron rigidum a synonym. USDA PLANTS lists it as Oligoneuron rigidum. Almost all other sources list it as Solidago rigida.