Life history

Species overview

Rock Whitlow-grass (Draba arabisans), a Wisconsin Special Concern plant, is found on exposed to shaded (often by white cedar) dolomite cliffs. Blooming occurs late June through late July; fruiting occurs early July through early September. The optimal identification period for this species is early July through early September.

Synonyms: Draba arabisans var. arabisans, D. arabisans var. superiorensis

Identification

• Distinguishing characteristics: Distinguished from D. glabella by having no simple trichomes on the bottom half of the stem. Each species has some star-shaped trichomes on the abaxial leaf surface, but these are sessile in D. arabisans and stalked in D. glabella.
• Flower characteristics: Loose, branched cluster (cyme); head to 10 cm long; flowers white, 4-parted, buds yellow.
• Fruit characteristics: pod long, narrow, smooth, twisting.
• Leaf characteristics: Lower leaves oblong, often with sharp teeth, hairy.

Phenology

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

Other

• Growth form: Forb-erect
• Vegetative reproduction:
• Life cycle: Perennial
• Comments: Associated Species: Thuja occidentalis, Zigadenus elegans, Solidago hispida, Abies balsamea, Betula alleghaniensis, B. papyrifera, Acer spicatum, Cystopteris bulbifera, Asplenium rhizophyllum, Cryptogramma stelleri.

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 Rock Whitlow-grass (Draba arabisans). 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 on exposed to shaded (often by white cedar) dolomite cliffs.
• Soils: Rocky, calcareous soils.

Natural communities

This table lists the natural communities that are associated with Rock Whitlow-grass. 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 Rock Whitlow-grass. 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 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.
• Avoid direct disturbance to sensitive microsites such as seeps, cliffs, and moss-covered boulders.

Management guidance

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

• Minimize disturbance to hydrology, including soil disturbance from rutting.
• 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.

Other resources

Links to additional Rock Whitlow-grass 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