Flower:

Open, branching cluster at the top of the stem, the branches ascending to widely spreading. The lowest branch is subtended by an erect, leaf-like bract that is up to 1½ inches long and usually shorter than the branch. Flowers are arranged 1 or 2 at a node, rarely in 3s, usually all on one side of a branch, with a small, brown, papery, scale-like bract at the base of a flower and a brown papery sheath surrounding the branch at the node.

Flowers are stalkless or nearly so with 6 tepals (petals and similar sepals) in 2 layers, the outer 1.6 to 2.3 mm long, the inner 1.8 to 2.8 mm long, both lance-oblong, blunt to pointed at the tip and straw-colored to chestnut brown with translucent whitish edging. Flowers have 6 stamens, the anthers (tips) much longer than the filament (stalk). In the center is a reddish ovary with a feathery, 3-parted style at the tip.

Leaves and stems:

A flowering stem has 1 to 4 alternate leaves all along the stem and usually 1 or 2 basal leaves, sometimes none. Leaves are ½ to 4 inches long, up to 1.1mm wide, round in cross-section with obscure cross-partitions. The sheath is open at the front. At the tip of the sheath is a pair of rounded lobes (auricles) .3 to 1 mm long.

Stems are slender, round in cross-section, smooth, erect, unbranched except in the flower clusters, single or a few from the base and creating colonies from long, creeping rhizomes.

Fruit:

Fruit is a single-chambered capsule, chestnut to reddish-brown, oval tapering to a pointed tip and about as long as or shorter than the persistent tepals. Seeds are few, oval, .3 to .5mm long, amber colored.

Fruit is not always developed, but instead flowers are often replaced by propagules known as bulbils. These vegetative buds sprout roots while still on the mother plant then drop off, taking hold in the soil where they land, or float away on the water to new locations.

Notes:

Juncus pelocarpus is occasional in sandy, peaty or mucky soil that is subject to seasonal fluctuations in water levels, or sometimes submersed in shallow water, and reaches the western edge of its range in Minnesota. It is a fairly distinctive Juncus, distinguished by the colonial habit, open, many-branched cluster, flowers and fruits mostly on one side of a branch, but most easily recognized by the bulbils when present, though they are tiny and magnification is recommended. Somewhat similar is Juncus bufonius, a clump-forming annual that lacks auricles on its sheaths, has leaf-like bracts at branch nodes, and the outer tepals are 3 to 6mm long, where Juncus pelocarpus tepals are less than 3mm long and has only a papery sheath at branch nodes.