• Don Yurewicz

Pondweeds with Small Floating Leaves

Updated: May 13

These three species of pondweed are characterized by small ovoid floating leaves and can be distinguished from one another by the size of the floating leaves and the size and shape of the submerged leaves.

Spiral Pondweed (Potamogeton spirillus)

Both submersed and floating leaves are produced, though floating leaves are few or may be absent. Floating leaves are firm, green, oval-elliptic, less than 1½ inches long, up to ½ inch wide, toothless, rounded to bluntly pointed at the tip, rounded to tapering at the base, on a stalk shorter than the blade. Blades have 5 to 15 veins.

Submersed leaves are more or less spirally arranged, green to reddish, linear and ribbon-like, often arching or coiled, up to 3 inches long, .5 to 2 mm wide, bluntly to sharply pointed at the tip, stalkless, and have 1 to 3 veins. Stems are flattened and branched. Colonies are often formed from spreading rhizomes. (Source: https://www.minnesotawildflowers.info/aquatic/spiral-pondweed)

Photo Source: https://nyc.books.plantsofsuburbia.com/potamogeton-spirillusspiral-pondweedpotamogetonaceae/

Vasey's Pondweed (Potamogeton vaseyi)

Floating leaves are oval and about 1/2 inch long. Submersed leaves are thread-like, very narrow (0.2-1 mm wide), and flaccid. Similar to snail seed pondweed but floating leaves are more ovoid and less elongated.

Vasey's Pondweed collected in South Cove by Maria Gross

Snail-Seed Pondweed

Snail-seed pondweed is characterized by very fine thread-like submersed leaves, with some floating leaves that are 7-veined, approximately 1/2 inch long and elongated-oval in shape. (Aquatic Plants and Algae of New Hampshire's Lakes and Ponds).

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