Tofieldia pusilla    (Michx.) Pers.

Small False Asphodel 


MN Status:
endangered
Federal Status:
none
CITES:
none
USFS:
yes

Group:
vascular plant
Class:
Monocotyledoneae
Order:
Liliales
Family:
Liliaceae
Life Form:
forb
Longevity:
perennial
Leaf Duration:
deciduous
Water Regime:
terrestrial
Soils:
rock
Light:
full sun
Habitats:

(Mouse over a habitat for definition)


Best time to see:

  Foliage   Flower   Fruit  
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Tofieldia pusilla Tofieldia pusilla Tofieldia pusilla Tofieldia pusilla Tofieldia pusilla

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Map Interpretation

Map Interpretation

  Synonyms

Narthecium pusillum

  Basis for Listing

Several small populations of Tofieldia pusilla occur on the North Shore of Lake Superior and nearby Isle Royale, but they are isolated from the main range of the species by approximately 650 km (404 mi.). This remarkable pattern of disjunction is seen in several other arctic species and is a result of the local, climate-modifying effect of Lake Superior that simulates growing conditions like those in arctic/alpine regions where these plants may be more common. The small population sizes and sensitive habitat requirements make the viability of the Minnesota populations a matter of immediate concern (U.S. Forest Service 1999).

Tofieldia pusilla was first found in Minnesota in 1891 by L. S. Cheney near Two Harbors in Lake County, and again the same year by J. H. Sandberg. Since the first two discoveries in 1891, four other locations of T. pusilla have been discovered in Cook County and one other has been discovered in Lake County. Four of them are quite small and the fifth consists of several hundred plants, but it is confined to an area of less than 1 m² (10.8 ft.² ). The original Two Harbors population has never been relocated. Tofieldia pusilla was listed as an endangered species in Minnesota in 1984.

  Description

Tofieldia pusilla is a distinctive but inconspicuous plant. It has several small, whitish or greenish flowers with 3 petals, 3 sepals, 3 styles, and 6 stamens. It has a single, glabrous, leafless pedicel and distinctive, sword-shaped basal leaves that are 2-ranked and linear. The fruit is a capsule (Gleason and Cronquist 1991).

A similar species, T. glutinosa (sticky false asphodel), occurs in prairies and fens in western Minnesota. It is a larger plant, and also differs from T. pusilla by having pedicels in clusters of 2 or 3, with 3 small bractlets at the top. In T. glutinosa, the pedicel is sticky and hairy (Gleason and Cronquist 1991).

  Habitat

All of the known Minnesota populations of T. pusilla occur in similar habitats on the shore of Lake Superior. This species prefers the massive outcrops of volcanic bedrock, not the unstable gravel beaches or the boulder-strewn shorelines. Suitable habitat is found intermittently from Two Harbors to Grand Portage, a distance of 200 km (124 mi.), but may total only a few hectares in extent. Tofieldia pusilla occurs in vegetation mats of Scirpus cespitosus (tufted bulrush), Carex spp. (sedges), and other species that persist in crevices in the shore outcrops of Lake Superior. These vegetation mats typically form in low depressions and at the margins of shore pools. Such habitats are small and localized, occurring just beyond the wave-washed zone or in protected areas nearer to lake level. Other rare species that may occur in the same habitat include Pinguicula vulgaris (butterwort), Bistorta vivipara (alpine bistort), and Selaginella selaginoides (northern spikemoss).

  Biology / Life History

Tofieldia pusilla is a relatively long-lived perennial. The plants flower in July and are insect-pollinated. The seeds are produced in August. Tofieldia pusilla may reproduce vegetatively from short rhizomes (Gleason and Cronquist 1991; U.S. Forest Service 1999).

The best time to search for T. pusilla is during flowering in July or while fruiting in August. This species is quite distinct even when flowers or fruits are not present, but it is very inconspicuous at such times and difficult to find.

  Conservation / Management

The most serious threats to the extant populations of T. pusilla include vandalism, over-collecting, recreation (trampling), shoreline development, pollution, the expanding gull population, and any other activities that can change the sensitive microclimate along Lake Superior (U.S. Forest Service 1999). Although the bedrock substrate of these populations is not typically directly threatened by destruction, the fragile vegetation mats that support this species are.

  Conservation Efforts in Minnesota

Much of the potential habitat along Lake Superior was inventoried by the DNR Minnesota Biological Survey from 1999-2002. It is possible that a few additional populations occur outside the surveyed areas, such as extreme northeastern Cook County.

  References

Gleason, H. A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. Second Edition. New York Botanical Garden, Bronx, New York. 910 pp.

U.S. Forest Service. 1999. Population viability assessment in forest plan revision. Statement of purpose and reason. Draft species data records: Tofieldia pusilla. United States Forest Service, Region 9.