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Aquatic and Wetland Vascular Plants of the Northern Great Plains

9. Ranunculaceae, the Buttercup Family

3. Myosurus L. -- Mouse-tail

1. Myosurus minimus L.


Small, glabrous, acaulescent annual 4-15 cm tall, with fibrous roots and a basal tuft of narrow, linear leaves mostly less than 1 mm wide. Flowers small, inconspicuous, usually few to many, borne singly above the leaves on slender peduncles, becoming more conspicuous in fruit; sepals greenish, usually 5, erect, spurred downward at the base, deciduous, 1.5-3.5(5.5) mm long, the blade lightly 3(5)-nerved on the back, usually longer than the spur; petals usually 5, sometimes none, inconspicuous, whitish or pinkish, about equaling the sepals; stamens 5-10; pistils many, borne on an elongate receptacle, ripening as a slender spike of usually more than 100, closely adherent, angular achenes; the achene bodies 1-2 mm long, with a sharp dorsal keel that extends beyond the body as an inconspicuous beak to 0.5 mm long, the beaks appressed in the spike; mature spike of achenes 1-6 cm long. Late Apr--Jun. Wet to moist places, sometimes in shallow water, usually where water stands only temporarily; scattered and probably more common than records indicate, as the plant is early and easily overlooked; (Ont. to B.C., s to FL, TX and CA; also s Europe, Asia and Australia).

A similar species, Myosurus aristatus Benth. ex Hook., has been recorded for Slope, Ward and Williams Cos., ND, and Daniels Co., MT. This plant also occurs in temporarily wet places, apparently in prairie. It differs from M. minimus mainly in the following ways: Sepals 1-nerved or rarely with 2 faint lateral nerves; achenes 20-50(90), rather loose in the spike, the achene bodies with a broad low keel and usually 2 marginal ridges on the back, the beaks conspicuous, 0.5-1.5 mm long, divergent from the spike; mature spike of achenes 0.5-2.5 cm long

GIF-Myosurus minimus
Myosurus minimus Note the very elongate heads of achenes that develop from each flower.
GIF- Distribution Map

Map key


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