Viola lanceolata var. lanceolata
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Basis for Listing
Viola lanceolata var. lanceolata 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 var. 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.
Viola lanceolata var. 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 var. 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).
Viola lanceolata var. 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 var. 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 var. 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 var. lanceolata also produces fertile, cleistogamous flowers that remain closed. They are self-pollinating and set seed without ever opening (Gleason and Cronquist 1991).
Conservation / Management
The main threat to V. lanceolata var. 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 var. 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 var. lanceolata. There are, however, populations on public land, which raises the possibility of enhanced management.
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.