Carex houghtoniana (Houghton's Sedge)

Plant Info
Also known as:
Genus:Carex
Family:Cyperaceae (Sedge)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; disturbed sandy, gravelly or rocky soil; roadsides, railroads, Jack pine stands, dunes, blowouts, shores, swamp edges
Fruiting season:June - August
Plant height:8 to 40 inches
Wetland Indicator Status:none
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

Spikes: Cluster type: spike

[photo of spikes] Separate staminate (male) and pistillate (female) spikes, with 1 to 3 staminate spikes crowded together at the tip of the stem, the terminal spike up to 1½ inches long and the others much smaller. Below the staminate spikes are 1 to 4 (usually 2 or 3) pistillate spikes, which are more widely spaced but typically held well above the leaves. Pistillate spikes are cylindric, up to 1½ inches long, stalkless or nearly so. At the base of each pistillate spike is a leaf-like bract that is longer than the spike but not usually longer than the inflorescence (group of spikes).

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

[photo of sheath and ligule] Leaves are basal and alternate, mostly near the base, 2.8 to 6 mm wide, erect to ascending and shorter than the flowering stem. Stem leaf sheaths are U to V-shaped, translucent whitish-green. The ligule (membrane where the leaf joins the sheath) is as long as or longer than wide. Leaves are hairless though may be slightly rough, M-shaped in cross-section when young. Leaves of vegetative shoots are longer and wider than those of flowering plants.

[photo of basal sheaths] Bases are wrapped in a red sheath that is not fibrous or only weakly so. Stems are erect, 3-sided and rough along the angles. Stems elongate up to 40 inches at maturity and remain longer than the leaves. Plants create colonies from long, creeping rhizomes.

Fruit: Fruit type: seed without plume

[photo of maturing pistillate spike] Fruit develops in late spring to mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Perigynia are ascending to spreading and not tightly crowded. Each pistillate spike contains 15 to 35 fruits.

[photo of perigynia, scales and achene] Pistillate scales are lance to egg-shaped, whitish or tinged brown along the edge with a green midrib, either tapering to a pointed tip or the midrib extending to a short awn, somewhat hairy or rough around the tip edge, and are shorter than the perigynia. Perigynia are 4.5 to 6.5 mm long, 2 to 2.9 mm wide, hairy, green turning maroon with maturity, strongly veined with 16 to 22 veins, oval-elliptic, tapering to a short, straight beak that has 2 distinct teeth at the tip. Achenes are smooth and 3-sided.

Notes:

Carex houghtoniana, sometimes listed as C. houghtonii, is a sedge of disturbed sandy, rocky or gravelly soils, and apparently requires repeated disturbance to persist. It is found along roadsides and railroads, Jack pine stands, sandy blowouts, shores, and other places subject to disturbance.

Carex is a large genus, with over 600 species in North America and 150+ in Minnesota alone. They are grouped into sections, the species in each group having common traits. Carex houghtoniana is in the Paludosae section; some of its common traits are: rhizomatous and forming colonies, leaves usually hairless, leaf sheaths often splitting into thread-like fibers and forming a ladder shape, leaves and sheaths with cross partitions between veins (septate-nodulose), basal sheaths red to purple and usually fibrous, terminal spike staminate, leaf-like bract subtending the lowest pistillate spike, perigynia usually hairy, beaked and toothed, achenes 3-sided in cross-section.

C. houghtoniana is distinguished from other members of Paludosae by the combination of: disturbance-prone habitat in sandy to rocky soil, perigynia up to 6.5 mm long, hairy and conspicuously veined. It most closely resembles Carex pellita, which has basal sheaths that are strongly ladder-fibrous, smaller perigynia (max 5mm) that are more tightly crowded on the spike, have less distinct veins, and is found primarily in wetlands and other areas with moist to wet soil. Some references describe the hairiness of C. houghtoniana perigynia as “sparse”, but the specimens we encountered seemed quite densely hairy so this trait is likely to be more variable than references indicate.

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More photos

Photos courtesy Peter M. Dziuk taken in Cook and Lake counties.

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