Solidago canadensis var. hargeri

Native

Moist to dry. Prairies, fields, ditches, roadsides, and forest openings. Full to partial sun.

August to October

Yellow ray florets, yellow disk florets

12″ to 78″

This is a 12″ to 78″ tall, though usually no more than 60″ tall, erect to ascending, perennial forb that rises on 1 to 20 or more stems from long, creeping rhizomes. It often forms large, dense patches. The roots and leaves exude toxic chemicals that inhibit the growth and survival of competing species (allelopathy).

The stem is erect or ascending, finely grooved, and leafy. It is not shiny and not covered with a whitish, waxy bloom (glaucous). It is moderately hairy both above and below the middle, though it may be hairless or nearly hairless near the base.

There are no basal leaves. Stem leaves are alternate, narrowly lance-shaped, and thin. Lower to middle stem leaves are 2″ to 7½″ long and 3 ⁄16″ to 13 ⁄16″ wide. The leaf blade is distinctly 3-veined. It tapers to the base and is attached to the stem without a leaf stalk. It tapers to a point at the tip with concave sides along the tip. The upper surface is hairless or slightly rough due to the presence of short, stiff hairs. The lower surface is sometimes hairless but usually has hairs along the midrib and main veins. The margins are toothed with sharp, forward-pointing teeth. Lower to middle stem leaves are usually withered by the time the plant is in flower. Middle to upper stem leaves are similar, 13 ⁄16″ to 4¾″ long, and 5 ⁄16″ to ½″ wide, largest near the middle, becoming gradually smaller as they ascend the stem. The margins are toothed, minutely toothed, or sometimes untoothed just below the inflorescence.

The inflorescence is a pyramidal, open, many-branched, spreading cluster up to 10″ across with 150 to 1300 flower heads. The flowering branches are long, hairy and strongly bent backward. The flower heads are arranged on one side of the branch.

The tiny flower heads are less than ¼″ wide. They have 5 to 13 yellow ray florets, usually 10 or fewer and averaging 9. They have usually 2 to 4, occasionally 5, yellow disk florets. The whorl of bracts surrounding the base of the flower head (involucre) is 1 ⁄16″ to ⅛″ long and yellowish in color. The corolla is 1 ⁄16″ to ⅛″ long.

Canada goldenrod (Solidago canadensis var. canadensis) stems are hairless or sparsely hairy from the middle to the base. The flower heads tend to have more ray florets, 7 to 15, and more disk florets, 3 to 6. It is found throughout the state.

Early goldenrod (Solidago juncea) stems are hairless.

Giant goldenrod (Solidago gigantea) stems are hairless and sometimes covered with a whitish, waxy bloom.

Salebrosa goldenrod (Solidago canadensis var. salebrosa) stems are hairless or sparsely hairy from the middle to the base. The flower heads tend to have more ray florets, usually 11 to 15, and have more disk florets, usually 5 to 11.

Tall goldenrod (Solidago canadensis var. scabra) often has large insect galls on the lower and middle part of the stem. Fresh plants often have a gray-green tone from the short hairs on the leaf surfaces. The plant is usually hairy throughout. The leaves are relatively thick and firm. The involucre is longer, ⅛″ to 3 ⁄16″ long.

A study in 2002 showed that Canada goldenrod inhibits the growth and survival of competing species by exuding toxic chemicals from its roots and leaves.