Hooker's Orchid (Platanthera hookeri)

Life history

Species overview

Hooker's Orchid (Platanthera hookeri), a Wisconsin Special Concern plant, is found in a variety of dry to moist, mostly mixed coniferous-hardwood forests. Blooming occurs late May through late July; fruiting occurs early July through late August. The optimal identification period for this species is early June through early September.

Synonyms: Habenaria hookeri, Habenaria hookeri var. abbreviata, Lysias hookeriana, Orchis hookeri

Identification

• Distinguishing characteristics: Stem bractless; ovary sessile.
• Flower characteristics: Flowers sessile, yellowish-green, ascending; lip lance-triangular, directed outward and upcurved, 8 to 12 mm; lateral sepals widely reflexed behind the flower, alongside the ovary; lateral petals lanceolate, incurved and may or may not be adjacent to the upper sepal; spur 13 to 25 mm, directed downward, tapering to the tip.
• Fruit characteristics: Capsules ridged, erect, more or less sessile and tapering on both ends, glabrous.
• Leaf characteristics: Leaves 2, basal, prostrate, 6 to 12 cm, broadly elliptic to rotund, seldom narrower.

Phenology

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

Other

• Growth form: Forb-erect
• Vegetative reproduction:
• Life cycle: Perennial
• Comments: Associated Species: Pinus strobus, P. resinosa, Quercus rubra, Betula papyrifera, Populus tremuloides, Aralia nudicaulis, Clintonia borealis, Aster macrophyllus, Trientalis borealis, Cornus canadensis.

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 Hooker's Orchid (Platanthera hookeri). 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.

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 a variety of dry to moist, mostly mixed coniferous-hardwood forests.
• Soils: In northern Wisconsin: sandy soils. In southern Wisconsin: humus-rich soils.

Natural communities

This table lists the natural communities that are associated with Hooker's Orchid. 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).

Ecological landscapes

This table lists the ecological landscape association scores for Hooker's Orchid. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

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 locating landings, staging areas, or access routes on or near known populations.
• 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 broadcast spraying of herbicides; use care with spot spraying.

Management guidance

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

• Maintain partial canopy to encourage woodland species; avoid closed-canopy conditions.

Other resources

Links to additional Hooker's Orchid information

Other links related to vascular plants (all exit the DNR website)

• Wisconsin Flora
• NatureServe Explorer
• Atlas of Wisconsin Prairie and Savanna Flora - Wisconsin State Herbarium
• USDA - NRCS Plants Database
• USGS Midwestern Wetland Flora - field office guide to plant species
• eFloras
• Cofrin Center for Biodiversity Herbarium
• Intermountain Herbarium Grasses of North America
• Orchids of Wisconsin

Photos

Click to view a larger version. Please considering donating a photo to the Natural Heritage Conservation Program for educational uses. Photo use