Flower:

1 to 5 clusters up to ¾ inch across at the tip of the stem, each cluster with 3 to 18 spikelets (flower clusters). The main cluster of spikelets is stalkless and hemispheric in outline, auxiliary clusters are smaller, on stalks up to about 3 inch long, hemispheric to cone-shaped to oval in outline. At the base of the group of clusters are 3 to 8 leaf-like bracts of varying lengths, mostly flat, 1 to 8 inches long, all erect to ascending.

Spikelets are flattened, oblong in outline, up to 1.5cm (~½ inch) long, with 3 to 18 florets, each subtended by a scale. Florets have 3 stamens and a 3-parted style. Scales are 1.5 to 2.5mm long, straw-colored to reddish brown, broadly egg-shaped to nearly round, 3 or 4-ribbed per side with a green midrib that extends to a minute awn .1 to .2mm long. The scales are arranged on opposite sides of the central spikelet stalk (rachilla), ascending and overlapping, sometimes barely so.

Leaves and stems:

Leaves are few, basal and alternate but near the base, V-shaped in cross-section, 1 to 6mm wide, 4 to 12 inches long. Basal sheaths are brown to reddish-brown. Stems are single or multiple from the base, erect to ascending, slender, 3-sided with rounded angles, and smooth. Plants form loose clumps and may form small colonies from knotty rhizomes.

Fruit:

The floral scales and achenes (seeds) drop off individually when mature, leaving the naked stalk behind. Achenes are 1.5 to 2mm long, 1 to 1.5mm wide, dark brown when mature, 3-sided with somewhat concave sides, broadly elliptic in outline, rounded at the tip end with a minute point at the top.

Notes:

Cyperus houghtonii is an uncommon flatsedge of dry, sandy soils, often found in or near Jack pine stands, and reaches the western edge of its US range in Minnesota. It is tracked by the DNR but does not currently have any special status in the state. It is one of three Cyperus species in Minnesota that prefer sandy soils and dry rather than wet habitats, the other two are Cyperus lupulinus and Cyperus schweinitzii. It is most similar to C. schweinitzii, which is the most common of the three, usually more robust than C. houghtonii, has sharply angled stems that are rough at least in the upper plant, and has larger scales (2.8 to 3.2mm long), with a more distinct awn up to 1mm long at the tip where C. houghtonii has smooth stems with rounded angles, nearly round scales 2.5mm long or less that have a minute awn. C. lupulinus typically has a single, smaller, hemispheric cluster densely packed with 15 to 60 spikelets, occasionally with 1 to 4 smaller, stalked spikelet clusters.