IUCN threat status:

Least Concern (LC)

Comprehensive Description

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Description

This is a submerged aquatic plant, producing leafy stems up to 3¼' long. The stems are light green or yellowish white, glabrous, and somewhat flattened (typically about 2 mm. across). Alternate leaves of fairly uniform size occur throughout the length of these stems. The leaf blades are 1½-3" (4-7.5 cm.) long, ¼-½" (6-12 mm.) across, and sessile; they are narrowly oblong to oblong in shape, while their margins are finely serrated and vertically undulate (wavy up-and-down). Leaf tips are typically rounded and blunt (obtuse), while leaf bases are more wedge-shaped (cuneate). The leaf blades are olive-green, reddish green, or brownish green in color and glabrous; their texture is stiff, rather than soft. Individual leaf blades have prominent central veins and 1-2 pairs of parallel lateral veins are sometimes visible. At the bases of leaf blades, lanceolate to ovate sheaths up to 1 cm. (1/3") long are produced; these sheaths are brownish green, glabrous, and early-deciduous. While all stems and leaves are typically submerged, the upper leaves toward the tips of stems are often within a few centimeters of the water surface. Upper stems occasionally terminate in short cylindrical spikes of flowers about ½-1" (12-24 mm.) in length. Less often, such spikes of flowers are produced from the axils of upper leaves. Their naked peduncles are ¾-3½" long; they hold the floral spikes slightly above the water surface. Individual flowers are quite small (about 1/8" or 3 mm. across), consisting of 4 greenish brown or greenish red sepals (or sepaloid connectives), 4 anthers, and 4 ovules. The blooming period usually occurs from late spring to early summer for about 1-2 weeks, although some plants may bloom later. The flowers are cross-pollinated by wind or water. Afterwards, the flowers are replaced by flattened achenes about 4-6 mm. in length that have long beaks (up to 4 achenes per flower). In addition to the achenes, this plant also produces winter buds (turions) from the tips of stems and the axils of leaves. These winter buds resemble congested rosettes of holly-like leaves spanning about 2 cm. across at maturity; they have a bur-like or cone-like appearance and stiff texture. After the achenes and winter buds are produced and released, the entire plant withers away during the summer. The winter buds drift in the water and eventually sink to the bottom of the body of water, where they can take root during the autumn, forming new plants that can survive the winter. The root system is fibrous.

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© John Hilty

Source: Illinois Wildflowers

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