Downy Willow-herb (Epilobium strictum)

Life history

Species overview

Downy Willow-herb (Epilobium strictum), a Wisconsin Special Concern plant, is found in fens, marshes, and sedge meadows. Blooming occurs late July through early September; fruiting occurs late July through early October. The optimal identification period for this species is late July through late September.

Synonyms: Epilobium densum, Epilobium molle

Identification

Distinguishing characteristics: According to the University of Michigan Herbarium this species is"easily mistaken at a glance for other species until one notices the distinctive glistening horizontal pubescence (on stems, leaves, and capsules), which is shorter than in the larger-leaved E. parviflorum and E. hirsutum. The entire leaves will distinguish it not only from these but also from specimens of E. ciliatum or E. coloratum with enough spreading pubescence that they might otherwise key here."
Flower characteristics: Petals pink, notched, 5 to 8 mm.
Fruit characteristics: Soft and usually covered with dense hair, composed of straight, spreading, or somewhat ascending hairs.
Leaf characteristics: Uppermost or all but the lowermost leaves alternate, simple, lanceolate or lance-linear, entire or nearly so, revolute, 2 to 4 cm long by 3 to 8 mm wide.

Phenology

Blooming phenology: late July through early September
Fruiting phenology: late July through early October
Optimum time to identify: The optimal identification period for this species is late July through late September

Other

Growth form: Forb-erect
Vegetative reproduction: Rhizomatous
Life cycle: Perennial
Comments: Associated Species: Carex stricta, Typha latifolia, Thelypteris palustris, Sagittaria sp., Epilobium leptophyllum.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - state and federal - and the rank (S and G Ranks) for Downy Willow-herb (Epilobium strictum). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Documented locations of Epilobium strictum in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State Status	SC
Federal Status in Wisconsin	none
State Rank	S3
Global Rank	G5
Tracked by NHI	Y

Habitats and landscapes

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

General habitat information

Habitat description: Found in fens, marshes, and sedge meadows.
Soils: Wet soils.

Natural communities

This table lists the natural communities that are associated with Downy Willow-herb. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).

Natural communities	score
Emergent Marsh	2
Northern Sedge Meadow	3
Southern Sedge Meadow	3
Calcareous Fen	2

Ecological landscapes

This table lists the ecological landscape association scores for Downy Willow-herb. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

Map of the Ecological Landscapes of Wisconsin.

Ecological landscape	score
Central Sand Hills	1
North Central Forest	3
Northeast Sands	2
Northern Highland	1
Northern Lake Michigan Coastal	1
Southeast Glacial Plains	3
Southern Lake Michigan Coastal	2
Superior Coastal Plain	2

Species guidance

The Endangered Resources Program has developed avoidance measures and management guidelines for plants on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback. Sources used in developing this information can be found here.

Avoidance measures

These are specific actions designed to avoid "take" (mortality) of this species.

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

Management guidance

Management guidelines are additional considerations that may help maintain or enhance habitat for this species

Maintain and restore open habitat through selective clearing and brushing.
Prescribed burns and/or brushing may be beneficial (dependent on local site conditions).
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.