Retzer Nature Center

Discover Brown’s Fen

Brown’s Fen is part of Retzer Nature Center. Waukesha County identifies it as a locally significant natural area and the largest high-quality remnant wetland on the property.

The photographed “An Uncommon Plant Community” sign explains what makes this fen special: mineral-rich spring water seeps through the ground, creating alkaline conditions that support plants adapted to that chemistry.

Another trail sign tells how wetlands associated with the Hallstrom and Brown farms were preserved when nearby land became the Kame Terraces subdivision in 1984. The fen later became part of Retzer.

County restoration work focuses on improving the fen’s water function and protecting its plant diversity. Follow the designated trails and boardwalks to explore this sensitive landscape.

Brown’s Fen beneath a clear blue sky

Historic farmstead building and interpretive sign

A landscape shaped by care

John and Florence Retzer began restoring their 90-acre property after its purchase in 1938, planting more than 26,000 trees, shrubs, and flowers. Florence left the land to Waukesha County in 1973 for park purposes.

Retzer now covers 483 acres, bringing together prairie, woodland, wetland, gardens, an Environmental Learning Center, and the Horwitz-DeRemer Planetarium.

Brian’s photographs follow both the broad landscape and its small details: a treefrog on a leaf, a chipmunk in a tree cavity, a turkey family on the trail, and tiny orchid flowers among fallen leaves.

Plan a visit

Finding Retzer

S14W28167 Madison Street
Waukesha, WI 53188

Entry and parking are free. No county park membership or daily permit is required.

Choose your route

The official map shows the fen, boardwalks, prairie loops, and Discovery Trail. Loop lengths range from 0.47 to 2.6 miles; connecting trails offer additional choices.

The map also identifies a separate quarter-mile accessible out-and-back route with pavement and boardwalk, with slopes of 5% or less. Snow is not removed from that route.

Hours & trail etiquette

Check the official page for current trail and building hours. Indoor hours are more limited than outdoor access.

Stay on marked trails. Dogs are not permitted; service dogs are allowed.

Make time to look closer

The Discovery Trail offers exploration stations and activities for a range of ages and abilities.

Open any photograph for the slideshow. “Load additional photos” adds the rest of that subject’s images to its gallery. These photographs reflect past visits and changing seasons.

Get directions Official trail map Hours & visitor information

16 photographs

Brown’s Fen & the overlook

Open wetland views, summer flowers, and the boardwalk route into Brown’s Fen.

Brown’s Fen beneath a clear blue sky at Retzer Nature Center, Wisconsin — Brown’s Fen beneath a clear blue sky

Joe-Pye weed and goldenrod across Brown’s Fen at Retzer Nature Center, Wisconsin — Joe-Pye weed and goldenrod across Brown’s Fen

Steps up to the Brown’s Fen overlook at Retzer Nature Center, Wisconsin — Steps up to the Brown’s Fen overlook

A view from the fen overlook at Retzer Nature Center, Wisconsin — A view from the fen overlook

Boardwalk beneath a blue sky at Retzer Nature Center, Wisconsin — Boardwalk beneath a blue sky

Boardwalk through late-summer flowers at Retzer Nature Center, Wisconsin — Boardwalk through late-summer flowers

Summer greenery across Brown’s Fen at Retzer Nature Center, Wisconsin — Summer greenery across Brown’s Fen

Goldenrod rising above the fen vegetation at Retzer Nature Center, Wisconsin — Goldenrod rising above the fen vegetation

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Boardwalk at the edge of the open wetland at Retzer Nature Center, Wisconsin — Boardwalk at the edge of the open wetland

A low boardwalk through wetland plants at Retzer Nature Center, Wisconsin — A low boardwalk through wetland plants

Trail junction leading toward Brown’s Fen at Retzer Nature Center, Wisconsin — Trail junction leading toward Brown’s Fen

Fen boardwalk surrounded by tall summer growth at Retzer Nature Center, Wisconsin — Fen boardwalk surrounded by tall summer growth

Wooden bridge on the fen route at Retzer Nature Center, Wisconsin — Wooden bridge on the fen route

A narrow boardwalk beneath arching foliage at Retzer Nature Center, Wisconsin — A narrow boardwalk beneath arching foliage

Boardwalk between tall wetland plants at Retzer Nature Center, Wisconsin — Boardwalk between tall wetland plants

A sunny boardwalk through late-season vegetation at Retzer Nature Center, Wisconsin — A sunny boardwalk through late-season vegetation

18 photographs

Woodland boardwalks & trails

Curving bridges, shady passages, and small streams along the wooded trails.

Boardwalk junction among the trees at Retzer Nature Center, Wisconsin — Boardwalk junction among the trees

Curving bridge through green woodland at Retzer Nature Center, Wisconsin — Curving bridge through green woodland

A small wooden bridge along the shaded trail at Retzer Nature Center, Wisconsin — A small wooden bridge along the shaded trail

Sunlight filtering into the wooded wetland at Retzer Nature Center, Wisconsin — Sunlight filtering into the wooded wetland

A small stream winding through the woods at Retzer Nature Center, Wisconsin — A small stream winding through the woods

Tall trunks in the conifer woods at Retzer Nature Center, Wisconsin — Tall trunks in the conifer woods

Wood-chip trail through the woods at Retzer Nature Center, Wisconsin — Wood-chip trail through the woods

Timber steps along the woodland trail at Retzer Nature Center, Wisconsin — Timber steps along the woodland trail

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A broad boardwalk winding into the woods at Retzer Nature Center, Wisconsin — A broad boardwalk winding into the woods

Narrow boardwalk through lush vegetation at Retzer Nature Center, Wisconsin — Narrow boardwalk through lush vegetation

Boardwalk disappearing into green woodland at Retzer Nature Center, Wisconsin — Boardwalk disappearing into green woodland

Woodland bridge beneath leafy branches at Retzer Nature Center, Wisconsin — Woodland bridge beneath leafy branches

A broad curve in the woodland boardwalk at Retzer Nature Center, Wisconsin — A broad curve in the woodland boardwalk

A shaded boardwalk lined with dense greenery at Retzer Nature Center, Wisconsin — A shaded boardwalk lined with dense greenery

Sunlit bridge along the woodland trail at Retzer Nature Center, Wisconsin — Sunlit bridge along the woodland trail

A small bridge along a winding wooded path at Retzer Nature Center, Wisconsin — A small bridge along a winding wooded path

Wooden footbridge beneath the trees at Retzer Nature Center, Wisconsin — Wooden footbridge beneath the trees

A trail leading toward the conifers at Retzer Nature Center, Wisconsin — A trail leading toward the conifers

18 photographs

Prairie hills, flowers & mist

Broad views of the grasslands, from misty mornings to sunny trails and late-summer blooms.

Low fog beyond the golden grassland at Retzer Nature Center, Wisconsin — Low fog beyond the golden grassland

Yellow prairie flowers across the hillside at Retzer Nature Center, Wisconsin — Yellow prairie flowers across the hillside

Mown path between colorful prairie flowers at Retzer Nature Center, Wisconsin — Mown path between colorful prairie flowers

A green hillside beneath a clear blue sky at Retzer Nature Center, Wisconsin — A green hillside beneath a clear blue sky

Mown path through tall golden grasses at Retzer Nature Center, Wisconsin — Mown path through tall golden grasses

Distant countryside beyond the prairie at Retzer Nature Center, Wisconsin — Distant countryside beyond the prairie

Wild bergamot blooming across the prairie at Retzer Nature Center, Wisconsin — Wild bergamot blooming across the prairie

Indiangrass across a golden meadow at Retzer Nature Center, Wisconsin — Indiangrass across a golden meadow

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An open field beneath scattered clouds at Retzer Nature Center, Wisconsin — An open field beneath scattered clouds

A grassy hill trail beneath a misty sky at Retzer Nature Center, Wisconsin — A grassy hill trail beneath a misty sky

A mown trail toward a fog-covered valley at Retzer Nature Center, Wisconsin — A mown trail toward a fog-covered valley

Prairie path beneath an overcast sky at Retzer Nature Center, Wisconsin — Prairie path beneath an overcast sky

Golden grasses across a rolling hill at Retzer Nature Center, Wisconsin — Golden grasses across a rolling hill

Summer flowers in the prairie at Retzer Nature Center, Wisconsin — Summer flowers in the prairie

A field of prairie blooms at Retzer Nature Center, Wisconsin — A field of prairie blooms

Wildflowers and grasses below the trees at Retzer Nature Center, Wisconsin — Wildflowers and grasses below the trees

A narrow path through tall autumn grasses at Retzer Nature Center, Wisconsin — A narrow path through tall autumn grasses

Summer prairie trail beneath a blue sky at Retzer Nature Center, Wisconsin — Summer prairie trail beneath a blue sky

7 photographs

Birds & a Wild Turkey family

Songbirds on their perches and a Wild Turkey adult with young poults along the trail.

Wild Turkey adult with three young poults at Retzer Nature Center, Wisconsin — Wild Turkey adult with three young poults

Wild Turkey poult on the boardwalk with an adult behind it at Retzer Nature Center, Wisconsin — Wild Turkey poult on the boardwalk with an adult behind it

Cedar Waxwing on a branch at Retzer Nature Center, Wisconsin — Cedar Waxwing on a branch

Indigo Bunting perched against a blue sky at Retzer Nature Center, Wisconsin — Indigo Bunting perched against a blue sky

Bobolink perched above the grassland at Retzer Nature Center, Wisconsin — Bobolink perched above the grassland

Brown Thrasher perched on a branch at Retzer Nature Center, Wisconsin — Brown Thrasher perched on a branch

Female House Finch on a branch at Retzer Nature Center, Wisconsin — Female House Finch on a branch

16 photographs

Mammals, insects & small discoveries

Watch the boardwalk edges and low leaves: the smaller encounters can be just as memorable as the views.

Gray Treefrog resting on a leaf at Retzer Nature Center, Wisconsin — Gray Treefrog resting on a leaf

Chipmunk peeking from a tree cavity at Retzer Nature Center, Wisconsin — Chipmunk peeking from a tree cavity

Red Squirrel on the boardwalk at Retzer Nature Center, Wisconsin — Red Squirrel on the boardwalk

Thirteen-lined Ground Squirrel beside a rock at Retzer Nature Center, Wisconsin — Thirteen-lined Ground Squirrel beside a rock

White-tailed deer partly hidden in the fen at Retzer Nature Center, Wisconsin — White-tailed deer partly hidden in the fen

White-tailed deer looking back from a field at Retzer Nature Center, Wisconsin — White-tailed deer looking back from a field

Northern Pearly-eye resting on a leaf at Retzer Nature Center, Wisconsin — Northern Pearly-eye resting on a leaf

A yellow butterfly visiting asters at Retzer Nature Center, Wisconsin — A yellow butterfly visiting asters

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Cottontail rabbit among woodland plants at Retzer Nature Center, Wisconsin — Cottontail rabbit among woodland plants

Eastern Cottontail beside the trail at Retzer Nature Center, Wisconsin — Eastern Cottontail beside the trail

A caterpillar on a curled leaf at Retzer Nature Center, Wisconsin — A caterpillar on a curled leaf

Honey bee visiting goldenrod at Retzer Nature Center, Wisconsin — Honey bee visiting goldenrod

Delicate pale mushrooms among wood chips at Retzer Nature Center, Wisconsin — Delicate pale mushrooms among wood chips

Small mushrooms growing together on wood at Retzer Nature Center, Wisconsin — Small mushrooms growing together on wood

Red Squirrel farther along the fen boardwalk at Retzer Nature Center, Wisconsin — Red Squirrel farther along the fen boardwalk

Thirteen-lined Ground Squirrel in green grass at Retzer Nature Center, Wisconsin — Thirteen-lined Ground Squirrel in green grass

35 photographs

Wildflowers, grasses & climbing plants

Close views of flowers, foliage, and fruit from the prairie, woodland, and wetland trails.

Shrubby cinquefoil flower at Retzer Nature Center, Wisconsin — Shrubby cinquefoil flower

Swamp thistle flowers at Retzer Nature Center, Wisconsin — Swamp thistle flowers

Riddell’s goldenrod against a blue sky at Retzer Nature Center, Wisconsin — Riddell’s goldenrod against a blue sky

Marsh bellflower at Retzer Nature Center, Wisconsin — Marsh bellflower

Spotted Joe-Pye weed flowers at Retzer Nature Center, Wisconsin — Spotted Joe-Pye weed flowers

Whorled milkweed flowers at Retzer Nature Center, Wisconsin — Whorled milkweed flowers

Purple prairie clover in bloom at Retzer Nature Center, Wisconsin — Purple prairie clover in bloom

Buttonbush flower head at Retzer Nature Center, Wisconsin — Buttonbush flower head

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American vetch flowers at Retzer Nature Center, Wisconsin — American vetch flowers

Big bluestem seed heads at Retzer Nature Center, Wisconsin — Big bluestem seed heads

Boneset flowers at Retzer Nature Center, Wisconsin — Boneset flowers

Compass plant flower at Retzer Nature Center, Wisconsin — Compass plant flower

Creeping bellflower along the trail at Retzer Nature Center, Wisconsin — Creeping bellflower along the trail

Devil’s beggarticks flower head at Retzer Nature Center, Wisconsin — Devil’s beggarticks flower head

Dodder twining around jewelweed at Retzer Nature Center, Wisconsin — Dodder twining around jewelweed

Prickly wild cucumber fruit at Retzer Nature Center, Wisconsin — Prickly wild cucumber fruit

Goldenrod flowering in the wetland at Retzer Nature Center, Wisconsin — Goldenrod flowering in the wetland

Hairy wood mint flowers at Retzer Nature Center, Wisconsin — Hairy wood mint flowers

Yellow loosestrife flower at Retzer Nature Center, Wisconsin — Yellow loosestrife flower

New Jersey tea flowers at Retzer Nature Center, Wisconsin — New Jersey tea flowers

Prairie loosestrife flower at Retzer Nature Center, Wisconsin — Prairie loosestrife flower

Giant hyssop flower spike at Retzer Nature Center, Wisconsin — Giant hyssop flower spike

Giant hyssop foliage and flowers at Retzer Nature Center, Wisconsin — Giant hyssop foliage and flowers

A close view of purple prairie clover at Retzer Nature Center, Wisconsin — A close view of purple prairie clover

Showy goldenrod flowers at Retzer Nature Center, Wisconsin — Showy goldenrod flowers

Smooth hydrangea flower cluster at Retzer Nature Center, Wisconsin — Smooth hydrangea flower cluster

Red sumac fruit at Retzer Nature Center, Wisconsin — Red sumac fruit

Sumac in flower at Retzer Nature Center, Wisconsin — Sumac in flower

White-flowered selfheal at Retzer Nature Center, Wisconsin — White-flowered selfheal

Wild cucumber flowers along a vine at Retzer Nature Center, Wisconsin — Wild cucumber flowers along a vine

A spiny wild cucumber fruit at Retzer Nature Center, Wisconsin — A spiny wild cucumber fruit

Wild cucumber fruit opening at the bottom at Retzer Nature Center, Wisconsin — Wild cucumber fruit opening at the bottom

Wild cucumber vine climbing a wooden railing at Retzer Nature Center, Wisconsin — Wild cucumber vine climbing a wooden railing

Wild mint flowers at Retzer Nature Center, Wisconsin — Wild mint flowers

Yellow coneflower at Retzer Nature Center, Wisconsin — Yellow coneflower

5 photographs

October lady’s-tresses

Small orchids reward a closer look at the woodland floor. These photographs show the flowers, flowering spike, and leaves.

A close view of October lady’s-tresses flowers at Retzer Nature Center, Wisconsin — A close view of October lady’s-tresses flowers

The flowering spike of October lady’s-tresses at Retzer Nature Center, Wisconsin — The flowering spike of October lady’s-tresses

October lady’s-tresses rising from the woodland floor at Retzer Nature Center, Wisconsin — October lady’s-tresses rising from the woodland floor

October lady’s-tresses foliage at Retzer Nature Center, Wisconsin — October lady’s-tresses foliage

4 photographs

Garden color

A few flowers photographed in the cultivated garden areas around the center.

African senna in the garden at Retzer Nature Center, Wisconsin — African senna in the garden

Sunflowers against a blue sky at Retzer Nature Center, Wisconsin — Sunflowers against a blue sky

Oregano flowers in the garden at Retzer Nature Center, Wisconsin — Oregano flowers in the garden

Red zinnia in the garden at Retzer Nature Center, Wisconsin — Red zinnia in the garden

15 photographs

History & discoveries along the trail

Historic farmstead buildings and photographed signs share the stories behind the landscape. Open a sign photograph to read it at full size.

Retzer Environmental Learning Center and planetarium sign at Retzer Nature Center, Wisconsin — Retzer Environmental Learning Center and planetarium sign

Historic farmstead building and interpretive sign at Retzer Nature Center, Wisconsin — Historic farmstead building and interpretive sign

A small historic farmstead building at Retzer Nature Center, Wisconsin — A small historic farmstead building

Stone outbuilding beneath the trees at Retzer Nature Center, Wisconsin — Stone outbuilding beneath the trees

Building a Legacy — history of the Retzer home at Retzer Nature Center, Wisconsin — Building a Legacy — history of the Retzer home

Putting Down Roots — John and Florence Retzer’s story at Retzer Nature Center, Wisconsin — Putting Down Roots — John and Florence Retzer’s story

An Uncommon Plant Community — Brown’s Fen interpretive sign at Retzer Nature Center, Wisconsin — An Uncommon Plant Community — Brown’s Fen interpretive sign

The Fen: A Living Gem interpretive sign at Retzer Nature Center, Wisconsin — The Fen: A Living Gem interpretive sign

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Animal Tracks exploration-station sign at Retzer Nature Center, Wisconsin — Animal Tracks exploration-station sign

Bird Nests exploration-station sign at Retzer Nature Center, Wisconsin — Bird Nests exploration-station sign

Hay Hill interpretive sign at Retzer Nature Center, Wisconsin — Hay Hill interpretive sign

A Legacy of Oaks interpretive sign at Retzer Nature Center, Wisconsin — A Legacy of Oaks interpretive sign

Look and Listen — prairie bird interpretive sign at Retzer Nature Center, Wisconsin — Look and Listen — prairie bird interpretive sign

Spider Webs exploration-station sign at Retzer Nature Center, Wisconsin — Spider Webs exploration-station sign

Welcome to Retzer interpretive sign at Retzer Nature Center, Wisconsin — Welcome to Retzer interpretive sign

Keep exploring

History and visitor details: Waukesha County — Retzer Nature Center. Trail routes: official trail map. Brown’s Fen context: Waukesha County Park and Open Space Plan and Conservation in the Parks. Fen chemistry and the farm-to-preserve story are described on the interpretive signs in Brian’s photographs above.

← Back to Places to Explore Official Retzer information View the trail map

Retzer Nature Center

Discover Brown’s Fen

A landscape shaped by care