Juncus dudleyi (Dudley's Rush)

Plant Info
Also known as:
Family:Juncaceae (Rush)
Life cycle:perennial
Habitat:sun; moist soil; shores, fens, wet ditches, marsh edges, swales
Fruiting season:June - August
Plant height:8 to 24 inches
Wetland Indicator Status:GP: FACW MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 6-petals Cluster type: panicle

[photo of clusters] Compact or loose branching clusters at the top of the stem, the branches erect to ascending; loose clusters are few flowered, compact clusters with up to 80 flowers. The lowest branch is subtended by an erect, leaf-like bract that usually rises well above the uppermost cluster. Flowers are single at the ends of short stalks, not in heads of 2 or more, nearly stalkless when clusters are compact and longer stalked when clusters are looser. Flowers have 6 tepals (petals and similar sepals) in 2 layers, 4 to 5 mm long, the inner and outer tepals about equal in size and shape, pointed at the tip and green to orange-brown with white papery edging. Flowers have a 3-parted style and 6 stamens, the anthers (tips) slightly shorter than the filament (stalk).

Leaves and stems: Leaf attachment: basal Leaf type: simple

[photo of thickened auricle, fresh and dried] A flowering stem has 2 or 3 alternate leaves near the base of the stem. Leaves are 2 to 12 inches long, up to 1mm wide, not much more than half as long as the flowering stem, more or less flat in cross-section though sometimes the edges are rolled in (involute). The sheath is open at the front. At the tip of the sheath is a pair of rounded lobes (auricles) .2 to .5 mm long, thickened (not papery), shiny, and often yellowish. Stems are round in cross-section, smooth, erect, unbranched, single or a few from the base and creating loose clumps and/or colonies from spreading rhizomes.

Fruit: Fruit type: capsule/pod

[photo of fruit] The tepals persist and become brown and ascending to spreading in fruit. Fruit is an elliptic, single-chambered capsule 2.9 to 3.6 mm long, brown to red-brown when mature, about as long as or slightly shorter than the tepals. Inside the capsule are numerous tiny seeds, elliptic to crescent-shaped, .4 to .7mm long, amber colored when mature with a white stub at the tip but no elongated tails.


Dudley's Rush is one of the most common rushes in Minnesota, found in the moist soils of fens, shores, swales, wet meadows and ditches, in both high quality and degraded, disturbed habitats. It is distinguished from similar looking rushes by the thickened, leathery auricles on the sheath, capsules about as long as or slightly shorter than the tepals, and tepals somewhat spreading in fruit. By comparison, Path Rush (Juncus tenuis) has long, triangular, papery auricles, capsules usually shorter than the tepals, and is generally a smaller plant. Inland Rush (Juncus interior) clusters are almost always tightly compact with very short branches, the auricles are about the same size as J. dudleyi but thin and papery, the tepals are smaller (3.3 to 4.4mm long) more appressed in fruit, is more consistently clump-forming, and is often found in the drier habitats of rock outcrops. Somewhat similar are Greene's Rush (Juncus greenei) and Vasey's Rush (Juncus vaseyi) both of which have capsules distinctly longer than the tepals and leaves that are more or less round in cross-section, not flat.

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More photos

Photos by K. Chayka taken in Ramsey County. Other photos courtesy Steve Eggers.


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