Variable-leaf or Waterthread Pondweed

Weed Description: A perennial with both floating and submersed leaves that are elliptic to oval in outline. This weed is a common aquatic weed of ponds, streams, and lakes that is found throughout the United States.

Leaves: Both floating and submersed leaves occur on the same plants. Floating leaves are elliptic to oval in outline, reaching 2 inches in length and ranging from 10 to 20 mm in width. Floating leaves usually have 7 to 11 distinct veins. Submersed leaves are arranged alternately along the stem and are usually smaller than the floating leaves. Submersed leaves have 3 veins, only 1 of which is usually noticeable. Submersed leaves have stipules at the base of the leaf petiole that forms a sheath around the stem.

Roots: Small, thin, rhizomes and fibrous roots.

Fruit: An achene that is very small.

Flowers: Flowers are spikes that occur on short flower stalks (peduncles) and arise just above the water surface.

Identifying Characteristics: The relatively small elliptical floating and submersed leaves and distinctively veined leaves of this plant helps to distinguish it from most other pondweeds.