PROTECTING WISCONSIN'S BIODIVERSITY

 
 
   
 
Scientific Name Common Name Global Rank State Rank Federal Status WI Status

Broad-leaved Twayblade (Listera convallarioides)

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Photo by Jim McEvoy

 

Counties with Mapped NHI Occurrences

Broad-leaved Twayblade (Listera convallarioides), a Wisconsin Threatened plant, is found on seepage slopes and ravine bottoms in hardwoods or mixed forests. Blooming occurs early-June through late-July, fruiting early-July through late-August. The optimal identification period for this species is late-June through July.

Epipactis convallarioides, Neottia convallarioides, Ophrys convallarioides

 
 
 

Broad-leaved twayblade is an erect forb, 10-30cm tall, with up to 20 pale green flowers. Its sepals and lateral petals are 4-5mm and reflexed. Its lip is greenish, translucent, 9-10mm long, and narrowed at the base, usually with a short tooth on each side near the narrow base. Its fruit is a capsule, 8cm long, that tapers on both ends, and is glabrous. It's leaves are opposite, arranged in a single pair, each leaf broadly ovate, 3-7cm long, and longer than the peduncle. Its axis, pedicels, and ovary are finely glandular pubescent.

It can be distinguished from Listera auriculata by its flower, which has a narrow-based lip (vs broad at base with auricles) and pedicels, which are finely glandular pubescent (vs glabrous). It can be distinguished from L cordata by the lip, which is shallowly cleft into 2 rounded lobes (vs cleft halfway to its base into two sharp-pointed lobes) and leaves, which are longer (over 2.5cm vs under 2.5cm).

Blooming occurs early-June through late-July, fruiting early-July through late-August.

Perennial. The optimal identification period for this species is late-June through July.

Associated species include Acer saccharum, Tsuga canadensis, Betula alleghaniensis, Thuja occidentalis, Carex scabrata, Circaea alpina, and Aster macrophyllus.

Broad-leaved twayblade prefers wet soils and is found on seepage slopes and ravine bottoms in hardwoods or mixed forests.

Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.

Avoid locating landings, staging areas, or access routes on or near known populations.

Avoid broadcast spraying of herbicides and use care with spot spraying.

Avoid site preparation that heavily disturbs herbaceous ground layer and soil, including bulldozing and furrowing, as well as grubbing and stump removal.

Follow BMPs, especially around streams and use care near ravines, steep slopes, cliffs, rock outcrops, etc.

Buffer management around unique microhabitats such as ephemeral ponds, seeps, etc.

This species requires shaded habitat conditions, maintain high forest canopy cover.

Minimize disturbance to hydrology, including soil disturbance from rutting.

Survey for and control invasive plants prior to conducting timber operations, as these can be spread by vehicles and often respond vigorously to increased light. See forestry BMPs for invasive species.

Species of Greatest Conservation Need (SGCN) are associated with habitats (or natural communities) and places on the landscape. Understanding relationships among SGCN, natural communities and ecological landscapes help us make decisions about issues affecting SGCN and their habitat and how to respond. Download the Wildlife Action Plan association score spreadsheet to explore rare species, natural communities and ecological landscape associations

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the Wisconsin Wildlife Action Plan because lack of information can threaten our ability to successfully preserve and care for natural resources.