Northern Prairie Wildlife Research Center
Western Wetland Flora
Field Office Guide to Plant Species
Juncus mertensianus Bong.
- Family: Rush (Juncaceae)
- Flowering: June-August
- Field Marks: This rush is distinguished by its solitary spherical head with flowers having purple-black sepals and petals and round-tipped capsules shorter than the sepals and petals.
- Habitat: Wet meadows, along streams, in fens, at many elevations in the mountains.
- Habit: Perennial herb from stout rhizomes.
- Stems: Upright, up to 10 inches tall, smooth.
- Leaves: Alternate, elongated, rolled into a hollow tube, septate, up to 1/10 inch wide.
- Flowers: Numerous, crowded into a solitary head, the head spherical, up to 1/2 inch in diameter, subtended by a bract that surpasses the inflorescence.
- Sepals: 3, lanceolate, pointed at the tip, purple-black, up to 1/6 inch long.
- Petals: 3, lanceolate, pointed at the tip, purple-black, up to 1/6 inch long, shorter than the sepals.
- Stamens: 6.
- Pistils: Ovary superior.
- Fruits: Capsules mostly triangular, rounded at the tip, up to 1/4 inch long, shorter than the sepals and petals.
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