Cladium mariscoides (Smooth Sawgrass)
|Also known as:||Twig Rush|
|Habitat:||sun; wet sandy or peaty soil; bogs, fens, shores, peatlands|
|Fruiting season:||June - August|
|Plant height:||12 to 40 inches|
|Wetland Indicator Status:||GP: OBL MW: OBL NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Small flower heads in a compact or (more often) open branching cluster at the top of the stem, sometimes with an auxiliary cluster in the upper leaf axil. Branches are variable in length, erect to ascending, the main branches subtended by an erect, leaf-like bract that usually overtops the cluster. Each flower head is hemispheric, 5 to 10 mm in diameter, with 3 to 10 spikelets (flower clusters), rarely more. Spikelets are 3 to 5 mm long, lance-elliptic and stalkless.
The flower at the tip of the spikelet is perfect (both male and female parts) with a 2 or 3-parted style and 2 stamens. Below the perfect flower are several staminate (male) flowers. Each flower is subtended by a scale, 2.5 to 3 mm long, lance-oblong, pointed at the tip, with a prominent midvein, and rusty red to brown. The lowest scale is empty and smaller than the other scales.
Leaves and stems:
Leaves are alternate, up to 12 inches long, 1 to 3.5 mm wide, hairless and mostly smooth, flat at the base but folded lengthwise and/or the edges rolled in (involute). The edges fuse near the tip making it round in cross-section.
The sheath is open at the tip with overlapping edges but fused (closed) below. Stems are smooth, erect, unbranched, and form colonies from slender rhizomes.
Fruit is a glossy, dry seed (achene), 2.5 to 3 mm long, round in cross-section, pointed at the tip, maturing from green to brown. The base is spongy, shrivels up and flattens out as it dries.
The common names Sawgrass and Twig Rush are both misleading—Cladium mariscoides is neither a grass nor a rush, but a sedge. At a casual glance it resembles a Juncus (rush) more so than a Carex (sedge) species, and looks similar to the budding stages of Juncus canadensis in particular. C. mariscoides is distinguished by leaves flat at the base and round at the tip, folded lengthwise and/or rolled in along the edges, closed sheaths (fused along the edges) except near the tip, clusters of 3 to 10 spikelets each with a single perfect flower at the tip and staminate flowers below, each flower subtended by a single scale, and the often rusty red coloring. While the distribution map shows its presence in about a third of the state, it is not common. According to the DNR, its preferred habitat in Minnesota is high-quality rich fen, a wetland habitat which is prone to degradation or outright destruction from activities such as agriculture, gravel mining, and groundwater appropriations. It was listed as a Special Concern species in 1984.
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- Cladium mariscoides plants
- a colony of Cladium mariscoides
- patches of red can be seen from a distance
- Cladium mariscoides with Spiranthes romanzoffiana
- maturing fruit
- plant with terminal and auxiliary cluster
Photos by K. Chayka and Peter M. Dziuk taken in Beltrami County and in Wisconsin. Photos courtesy Steve Eggers taken in Polk County.
Have you seen this plant in Minnesota, or have any other comments about it?