Alisma triviale Pursh – Northern Water Plantain

 

General: Perennial, aquatic, herb with a 30–100 cm tall, leafless flowering stalk. The root system consists of a cluster of shallow fibrous roots and rhizomes.

 

Leaves: Basal, up to 18 cm long, oval or elliptic, long-stalked, with parallel veins; submerged, ribbon-like leaves sometimes present. The leaf margins are smooth, while both the upper and lower surfaces are hairless.

 

Flowers: Up to 8 mm wide, with three white to pink petals, three green sepals, and six stamens. There is a small patch of yellow at the base of each petal, while the center of the flower is green. The flowers appear on 1–4 cm long stalks, in large open clusters (panicles) throughout the summer. This inflorescence is heavily branched and more or less erect. The green flowering stalks are hairless and sometimes angular or finely ribbed along their length.

 

Fruits: Achenes, 2–2.5 cm long, grooved on one side and ridged on other side. Each flat-sided seed is longer than broad, with a tiny beak at the top.

 

Where found: In marshes, lakes, streams and ditches from Newfoundland to British Columbia, south to Carolina, Florida and Texas.

 

Notes: This species may also be called Alisma plantago-aquatica in older references. A. plantago-aquatica, commonly called European water-plantain, is a perennial flowering plant widespread across most of Europe and Asia from Portugal and Morocco to Japan, Kamchatka and Vietnam. It is also regarded as native in northern and central Africa as far south as Tanzania. It is reportedly naturalized in southern Africa, Australia, New Zealand, Alaska, British Columbia, Washington State and Connecticut.

 

In our pond, the tall flowering stalks have a tendency to flop. [Brian Haddon, GOWGHS]

 

 

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