Basis for Listing

Viola lanceolata (lance-leaved violet) is a species of low, moist meadows, moist swales in sand dunes and savannas, and occasionally sandy lakeshores. The majority of the original Minnesota populations probably occurred on the Anoka Sandplain in Sherburne, Isanti, and Anoka counties. While severe habitat loss was apparent in 1984 when V. lanceolata was designated a state special concern species, lack of current data prevented it from being assigned a more protective status. An intensive survey of east-central counties completed by 1995 subsequently provided adequate data to elevate the status of this species to state threatened in 1996.

Although 28 sites of V. lanceolata were found during the survey, nearly all were isolated pockets of remnant habitats. Land conversion has destroyed over 90% of this species' habitat on the Anoka Sandplain, and the remaining fragments are increasingly threatened by development. Recently, there have been discoveries of V. lanceolata in northeastern Minnesota, where it appears to occur sporadically over a relatively large area. Field surveys are ongoing in that area, but it is still too early to know the significance of these discoveries.

  Description

Viola lanceolata is one of a small group of white-flowered acaulescent, or stemless, violets; plants whose petioles and peduncles all sprout basally from the stolons or rhizomes. Flowers of V. lanceolata are consistently white, although all violets with cyanic (blue or bluish color) flowers (rather than yellow) occasionally produce white-flowered forms. Fruits are green and ellipsoid, 5-8 mm (0.2-0.3 in.) long, and contain many tiny, brown seeds. The narrow, serrate leaves are quite distinctive. They taper to the base, and in most cases are more than 3 times as long as wide (Gleason and Cronquist 1991).

  Habitat

Viola lanceolata occurs in low, moist meadows with a sandy substrate, moist swales in sand dunes and savannas, and occasionally on sandy lakeshores. One recent population was found in dry mud in an old beaver lodge. The seeds that produced those plants probably originated on the nearby lakeshore. Viola lanceolata is also known by the common name white bog violet. Although it does not occur in true bogs, it is sometimes found in peaty wetlands and meadows that might be known locally as bogs.

  Biology / Life History

Viola lanceolata is a short-lived perennial that flowers throughout the spring and early months of summer. In addition to the small but showy flowers, V. lanceolata also produces fertile, cleistogamous flowers that remain closed. They are self-pollinating and set seed without ever opening (Gleason and Cronquist 1991).

The best time to search for V. lanceolata is in spring, when its distinctive leaves are fully developed but the surrounding vegetation has not yet grown over it. Even later, the peculiar lance-shaped leaves are distinctive.

  Conservation / Management

The main threat to V. lanceolata is loss or degradation of its wetland habitats. For most of the past century, agriculture was the greatest cause of habitat loss. The only wetlands that were spared were those that were too difficult to fill or drain, or those where the terrain was too difficult or too uneconomical to convert. Today, the greatest threat is from urban and suburban developments, particularly large residential and commercial complexes and the roads and utility corridors that serve them. Other threats to the habitats of V. lanceolata include invasive plants, trampling by off-road vehicles, altered groundwater and surface water hydrology, and woody plant encroachment. There are few habitats left on the Anoka Sandplain that still support native vegetation. All those that do survive will require active management to replace natural ecosystem functions that were lost when the landscape was fragmented. This may include the cautious use of prescribed fire, manual removal of invasive plant species, protection from herbicides and sedimentation, and provision of a large buffer area to reduce impacts from adjacent developed land. The management needs of recently discovered populations in the northeast have not yet been assessed.

  Conservation Efforts in Minnesota

No specific conservation efforts have been initiated for the benefit of V. lanceolata. There are, however, populations on public land, which raises the possibility of enhanced management.

  References and Additional Information

Ranua, V. A. and C. Weinig. 2010. Mixed-mating strategies and their sensitivity to abiotic variation in Viola lanceolata L. (Violaceae). The Open Ecology Journal 3:83-94.

Russell, N. H. 1954. Three field studies of hybridization in the stemless white violets. American Journal of Botany 41(8):679-686

Solbrig, O. T., W. F. Curtis, D. T. Kincaid, and S. J. Newell. 1988. Studies on the population biology of the genus Viola. VI. The demography of V. fimbriatula and V. lanceolata. Journal of Ecology 76:301-319.