Carex woodii Dewey
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Basis for Listing
Until fairly recently, Carex woodii was considered a very rare species in Minnesota and believed to be confined to relatively few sites in mature forests in the southeastern corner of the state. Beginning in the 1990s, an increased awareness of this species resulted in numerous new records from that part of the state. This was primarily the result of survey work conducted by the Minnesota County Biological Survey (MCBS). As field botanists from MCBS moved northward, they documented occurrences at several additional sites in central Minnesota - a region of the state where C. woodii had not been found before - and even one site in the northeast. Such a widespread distribution in the state was unexpected, and may indicate that a renewed look at the conservation needs of this species is warranted. Carex woodii was listed as a special concern species in Minnesota in 1984.
Carex woodii is a perennial sedge that grows to a maximum height of about 45 cm (18 in.). The bases of the stems are a dark, reddish-purple color and they grow in loose to rather dense tufts. These tufts can produce horizontal rhizomes that can grow to more than 10 cm (4 in.) in length. The leaf blades are flat and up to 4 mm (0.16 in.) wide. The inflorescence consists of 2-3 spikes. The terminal spike is 2-3 cm (0.8-1.2 in.) long and composed of male flowers. The lateral spikes are 1-3 cm (0.4-1.2 in.) long and composed of female flowers. The perigynia (the membranous covering of the seeds) are broadly ellipsoidal to obovoid in shape, 2.5-3.7 mm (0.10-0.15 in.) long, 1.2-1.7 mm (0.05-0.07 in.) wide, and rounded to a beakless tip. Carex woodii is most similar in appearance to the prairie species, C. tetanica (rigid sedge), but with dark, reddish-purple color on the stems.
The Minnesota records of C. woodii are primarily from loamy soil in mesic hardwood forests where there is a lush and diverse groundlayer dominated by spring ephemerals. Acer saccharum (sugar maple) is the most frequently recorded canopy tree, followed by Tilia americana (basswood), Quercus rubra (red oak), Fraxinus pennsylvanica (green ash), Q. macrocarpa (bur oak), and Populus tremuloides (trembling aspen). Carex woodii can also grow in moist soils on the periphery of groundwater seepage zones and some records have noted a proximity to hillside seeps.
Biology / Life History
Carex woodii is a perennial sedge adapted to the low light conditions found in forest interiors. Seeds are produced, but not with great regularity or in great abundance; reproduction is primarily vegetative rather than sexual. It is not uncommon to find this sedge growing in relatively large, sterile patches a few meters across. Sometimes the patches are dense enough to be called sods as they are formed by an interconnected system of rhizomes buried a few inches beneath the surface. These sods are apparently quite persistent, sometimes noted to survive, at least for a few years, after their forest habitat had been subjected to logging or livestock grazing.
Conservation / Management
Not surprisingly, management considerations for C. woodii are essentially the same as management considerations for mesic forests communities as a whole. In order to reduce the risk of invasion by non-native species, it is important to protect the integrity of the tree canopy and the health of the soil. Although C. woodii has been observed to persist for short periods after logging and cattle grazing, such activities can risk the long-term viability of C. woodii and the biotic integrity of the plant community. Clearly, naturally occurring stochastic events such as windstorms and lightning strikes will result in occasional, localized canopy gaps. However, these gaps are quickly filled by the rapid growth of sapling trees in the understory. Some invasive species, most notably Alliaria petiolata (garlic mustard), may not even need a perturbation to become established. Therefore, it is important that invasive species be carefully monitored and actions taken to prevent their spread.
Conservation Efforts in Minnesota
Several forest tracts that harbor populations of C. woodii are in the ownership of public land management agencies. Most of these tracts are managed for timber production, although some are managed for the preservation of the forest community and attendant ecological processes.
Rothrock, P. E., and A. A. Reznicek. 2002. Carex sect. Paniceae. Pages 426-431 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 23. Oxford University Press, New York, New York.