European bur-reed

LC - Least Concern

NNR - Unranked

SNR - Unranked

not listed

OBL - Obligate wetland

OBL - Obligate wetland

OBL - Obligate wetland

European bur-reed is an 8″ to 24″ tall, erect, perennial, emergent or floating, aquatic forb that rises on basal leaves and a single stem from fibrous roots and an underground horizontal stem (rhizome).

Basal leaves are strap-shaped (linear). Some may stand above the water (emergent), while others float on the surface. They surround (sheath) the stem at the base and taper to a point at the tip. Emergent leaves are stiff, spongy, 12″ to 32″ long, and ⅛″ to ⅜″ wide. They are parallel-veined and flat (not rounded on the back), and partially to entirely folded with a raised ridge (keeled). The upper and lower surfaces are hairless. The margins are untoothed. Floating leaves are similar but limp, up to 80″ long, ⅛″ to 11 ⁄16″wide, and keeled, at least near the base.

Stem leaves are reduced to persistent, leaf-like bracts. The bracts are alternate, ascending or spreading, broadened and thickened at the base, and otherwise similar to the basal leaves. They become much smaller as they ascend the stem.

The stem is hairless, unbranched, and usually erect, sometimes floating. Stem leaves are

Male and female inflorescences are produced on the same plant. Flowers are grouped in dense, spherical, unisexual heads with numerous flowers on an erect, unbranched, somewhat zigzagged, 4″ to 8″ long stalk at the end of the stem. There are usually 3 to 7, sometimes up to 10, male (staminate) heads at the top and 1 to 6 female (pistillate) heads below. The lowermost pistillate heads are on stalks that connect to the stem above, not in, the uppermost bract axils. The upper pistillate heads and the staminate heads are stalkless. Pistillate heads are ⅝″ to 1⅜″ in diameter when in fruit.

Individual flowers are tiny. Staminate flowers have 1 to 6 tepals and 2 to 8 stamens. The tepals are free, not united at the base. They are scale-like, club-shaped to spatula-shaped, and green at first, soon turning white or whitish. They do not have a dark thickened area just below the tip. The margin at the tip is irregularly toothed, appearing gnawed. The stamens have filaments that are much longer than the tepals. The anthers are attached by the base to the filaments. Pistillate flowers have 1 style with 1 stigma. The style is much longer than the tepals. The stigma is white to greenish. The flowers are pollinated by wind.

The fruit is similar to and often called an achene but is actually a drupe, with a fleshy exterior surrounding a single stone-like seed. It is shiny, 3 ⁄16″long, 1 ⁄16″ wide, and spindle-shaped, widest at the middle and tapered at both ends. It is green at first, turning reddish-brown at maturity. The dried style persists as a beak attached to the tip. The beak is shorter than the body.

8″ to 24″

White or whitish

American bur-reed (Sparganium americanum) inflorescence is sometimes branched. The pistillate heads are stalkless in the bract axils. The fruits are not shiny.

Common bur-reed (Sparganium eurycarpum) is a larger plant, up to 40″ tall. All or most of the pistillate flowers have two stigmas. The fruit is broadly pyramid-shaped.

Narrow-leaved cattail (Typha angustifolia) leaves are conspicuously rounded on the back.

Shallow water. Margins of lakes and swamps, in ponds and streams, and in backwaters of large rivers. Full sun. Muddy soil.

June to August

Sources

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

Native

Common

The genus Sparganium was formerly placed by itself in the family Sparganiaceae. Phylogenetic analysis showed it to be closely related to cattails in the genus Typha. It was moved to the cattail (Typhaceae) family in 2009.

Plant

Male Inflorescence

Female Inflorescence