Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
Juncus platyphyllus (Wiegand) Fernald
- Family: Rush (Juncaceae)
- Flowering: June-September
- Field Marks: The distinguishing features of this rush are the flat leaves, purplish leaf
sheaths, and long, firm auricles of the leaf sheath.
- Habitat: Marshes.
- Habit: Perennial herb from knotty rhizomes, in dense clumps.
- Stems: Upright, smooth, up to 3 feet tall.
- Leaves: Elongated, flat, but becoming rolled into a tube when dry, up to 1/4 inch wide; sheaths purplish; auricles of the sheaths much prolonged, firm.
- Flowers: 2-6 in a head, with several heads forming a cyme up to 5 inches long, subtended by a bract longer than the cyme.
- Sepals: 3, pale brown, lanceolate, erect, free from each other, up to 1/4 inch long.
- Petals: 3, pale brown, lanceolate, erect, free from each other, up to 1/4 inch long.
- Stamens: 6.
- Pistils: Ovary superior, smooth.
- Fruits: Capsules ovoid, brown, up to 1/4 inch long.
- Notes: Gleason and Cronquist call this plant J. tenuis var. dichotomus. Juncus platyphyllus has firm, drab to grayish green, round-tipped auricles on the leaf sheath, while J. tenuis has thin, whitish, lance-oblong auricles. The seeds are eaten by waterfowl.
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