Canadian clearweed

not listed

N5 - Secure

SNR - Unranked

not listed

FAC - Facultative

FACW - Facultative wetland

FACW - Facultative wetland

Canadian clearweed is a 4″ to 20″ tall, erect, annual forb that rises on a single stem from fibrous, shallow, adventitious roots. It often forms large colonies.

The stems are erect, light green grayish-green, or reddish-green, transparent, unbranched, smooth, and hairless. The are round in cross section.

The leaves are opposite, thin, elliptic to broadly elliptic or egg-shaped, 1¼″ to 5″ long, and ⅜″ to 3½″ wide. They are on leaf stalks that are often 1″ long or longer. Each leaf is equal in size to the leaf on the opposite side of the stem. The leaf blade is broadly wedge-shaped or rounded at the base. It does not have ear-like lobes at the base. It is slightly transparent, most noticeably on the lower surface. The margins are coarsely toothed with sharp or rounded, forward-pointing teeth. The tooth at the tip is elongated. The upper surface is medium to dark green, shiny, and hairless. The lower surface is light green and hairless. There are three parallel main veins, the midvein and two lateral veins that arch toward the tip. The veins are conspicuously depressed on the upper surface, giving the leaf blade a quilted or wrinkled appearance. The leaves turn bright yellow in the fall.

The inflorescence is a crowded or loose, ¼″ to 1¼″ long, branched, flat-topped cluster (cyme) rising from the upper leaf axils. The cyme is 55% to 70% as long as wide and shorter than the leaf stalk. It contains both male and female flowers.

The flowers are less than ⅛″ long and about 1 ⁄32″ in diameter. Male flowers have no petals, 4 greenish-white sepals, and 4 stamens. Female flowers have no petals, 3 greenish-white sepals, and 1 style. The flowers are not fragrant.

The fruit is a dry, tear-drop shaped, 1 ⁄32″ to 6 ⁄16″ long seed case (achene). It is green or greenish-yellow at maturity, sometimes with fine, purple lines. The purple lines, when present, are sometimes slightly raised.

4″ to 20″

Greenish-white

Moist to wet. Woodlands, woodland margins, and streambanks. Full shade. In rich soil.

July to September

Sources

2, 3, 4, 5, 7, 28, 29, 30.

Native

Common