Floating Bur-reed (Sparganium fluctuans)

Floating Bur-reed (Sparganium fluctuans)

The Floating Bur-reed (Sparganium fluctuans), also known as the Floating-leaved Bur-reed, is an emergent, perennial forb/herb found in French Hill Pond. It belongs to the Bur Reed Family (Sparganiaceae). There is only one genus in this family, Sparganium, and over a dozen species. The order to which this plant belongs is Typhales. The family and genus names are from an old term for "bands" or "ribbons." probably referring to the ribbon-like leaves. The species name is from the Latin for "wavy" or "fluctuating."

The leaves of this plant are alternate on the nodes of a usually submerged or semi-submerged stem. The stem can be up to five feet (1.6 meters) long.  Each leaf is spear-like, flat, thin to the point of being translucent, up to 40 inches (one meter) long and less than one inch (2.54 centimeters) wide. These plants grow in shallow water. The following photograph shows Floating Bur-reed leaves in the southern part of French Hill Pond. These leaves are generally less than half the width of the  Erect Bur Reed (Sparganium americanum) leaves.

Floating Bur-reed Co;ony

The white  to brown to green flowers are born on relatively straight stems. There may be more than one flower per stem and the individual flowers lack stalks. The flower is about one inch (2.54 centimeters) in diameter, usually brown in the center and white to green towards the edges. The mature flower may be almost all brown. Each flower is unisexual (either male or female) with flowers of both sexes on the same plant. Note the yellow buds in the photograph below. The flowers, being on straight stems and having the white to brown colors, are distinctly different from the flowers of the  Erect Bur Reed (Sparganium americanum). This plant flowers from July through August. 

Floating Bur-reed (Sparganium fluctuans)

The fruit is an achene (small, dry, encapsulated seed that does not open before germination) with a curved beak about 0.08 inch (2 millimeters) to 0.2 inch (5 millimeters) long and about 0.08 inch (2 millimeters) wide. The fruits develop in a bur-covered ball about ½ inch (1.27 centimeters) in diameter created by a female flower.  A close-up of the fruit ball is shown in the following photograph.

Floating Bur-reed Achene Ball

The following microphotograph at 20X magnification shows the achene imbedded in a fleshy mass to form the burs of the fruit ball.

Floating Bur-reed Achene Ball

The next microphotograph at 20X magnification shows an individual achene. Note the reddish color giving the whole fruit ball a reddish-brown hue. 

Floating Bur-reed Achene

The root system is rootstock.

Floating Bur-reeds serve as food for wildlife, help stabilize the shoreline and help filter water runoff as it enters the pond.

These plants are sometimes cultivated in water gardens.


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