Carex plantaginea Lam.
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Basis for Listing
The range of this distinctive forest species is geographically centered in the eastern Great Lakes region. Minnesota appears to be at the extreme western periphery of its range. Carex plantaginea appears to be common only in the center of its range and becomes increasingly sporadic and uncommon south and west of that area. Based on collection records, C. plantaginea seems to be one of the rarest sedges in southern Minnesota. Because of its broad evergreen leaves, it would be difficult to overlook this plant in the field or mistake it for another species. The few collection and sight records probably reflect its true rarity in the state. Another measure of its decline is the well-documented loss of its habitat in maple-basswood forests in east-central and southeastern Minnesota due to agriculture, residential, recreational, and commercial development. Given its rarity in the state and the threats to its habitiat, C. plantaginea was listed as an endangered species in Minnesota in 1996.
Sedges are grass-like, perennial plants that can be easily identified to the genus Carex by their three-ranked leaves, closed sheaths, and triangular (only occasionally round), mostly solid stems with a terminal inflorescence. Identifying a sedge to the species level is often difficult though, and positive identification usually requires mature perigynia (the structure that appears to be the seed or fruit but is actually a bract enclosing the ovary) to be present. Carex plantaginea is quite distinctive however, and easily identified. The stem has no green leaves, but it has numerous purplish sheaths. There are conspicuous basal evergreen leaves that are strongly reddened at the base and very broad, in fact, the broadest of any Minnesota sedge. Carex albursina (white bear sedge) and C. careyana (Carey's sedge) occur in the same habitat and also have broad basal leaves, but they have a leafy stem.
Carex plantaginea occurs in moist, shaded, hardwood forest in southeastern Minnesota. Within such forests it may favor north-facing slopes, steep ravines, or other cool, protected microhabitats. Acer saccharum (sugar maple) and Tilia americana (basswood) are often the dominant canopy trees. Populations of C. plantaginea may range from only a few individuals to 100 or more.
Biology / Life History
Carex plantaginea acts like a spring ephemeral, sending up its fertile stems early in the spring. These stems continue to elongate throughout May and early June, eventually fall over onto the forest floor, and disappear by mid-summer. This may be a dispersal mechanism for the perigynia. By late spring when the culms are elongating, the plant sends up a flush of basal leaves that grow through the summer and then overwinter intact or at least partially intact. This life cycle is similar to the other rare, wide-leaved, red-based sedge C. careyana, but different from the common C. albursina, a wide-leaved, brown-based sedge that sends up its fertile culms with the basal leaves in mid- to late spring.
Conservation / Management
Agricultural, residential, and commercial development in southeastern Minnesota has reduced the extent of the original habitat of C. plantaginea to small, scattered remnants. These remnants are often further degraded by livestock grazing, which results in direct loss of plants, soil compaction, trampling, and the introduction of non-native invasive species. The habitat can also be degraded by certain forms of logging, when canopy removal causes warming and drying of the forest floor.
Conservation Efforts in Minnesota
The Minnesota DNR County Biological Survey has been completed in the range of this species in the state, providing reliable information about its distribution and abundance.