Canada goldenrod

not listed

N5 - Secure

SNR - Unranked

not listed

FACU - Facultative upland

FACU - Facultative upland

FACU - Facultative upland

Canada goldenrod (var. canadensis) 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 and leafy. It is not shiny and not covered with a whitish, waxy bloom (glaucous). The lower half of the stem is hairless or sparsely hairy. The upper half is densely covered with short hairs.

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 1,300 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 7 to 18, usually 15 or fewer, yellow ray florets and 3 to 6 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.

12″ to 78″

Yellow ray florets, yellow disk florets

Early goldenrod (Solidago juncea) stems are hairless.

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

Harger’s goldenrod (Solidago canadensis var. hargeri) stem is moderately hairy both above and below the middle, though it may be hairless or nearly hairless very near the base. The flower heads tend to have fewer ray florets, 5 to 10, averaging 9, and have fewer disk florets, 2 to 4. It has been recorded only in Grant County in western Minnesota.

Missouri goldenrod (Solidago missouriensis) is a shorter plant, no more than 32″ tall. The stem is hairless below the inflorescence. Lower stem leaves are on winged leaf stalks up to 2″ long. The leaves are somewhat thickened and stiff, not thin. They become noticeably smaller toward the top of the stem. The upper and lower leaf surfaces are hairless. A tight bundle of small, wing-like leaves often appear in the leaf axils. The flower heads have 8 to 20 disk florets.

Tall goldenrod (Solidago altissima ssp. altissima) is moderately to densely hairy both above and below the middle. There are often 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.

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

August to October

Canada goldenrod produces chemicals that help it compete against nearby plants (allelopathy). The roots and leaves exude toxic chemicals that inhibit the growth and survival of competing plants. The effect has been documented repeatedly in the lab but is less evident in the field.

Sources

4, 7, 29, 30.

Native

Common