Stellaria longipes ssp. longipes
Basis for Listing
Stellaria longipes ssp. longipes is a highly polymorphic, circumpolar species complex with a wide distribution in diverse climates throughout the Northern Hemisphere (Chinnappa and Morton 1984). In one form or another (there are multiple varieties and subspecies), it is common across much of Canada and in the western mountains, but it is rare in the region of Minnesota. In fact, it is currently known to occur in only two northwestern counties; there is a historic record from Otter Tail County, but that population has never been relocated. The species' habitat requirements are not well known, but it is believed that S. longipes ssp. longipes occurs in more-or-less natural habitats of prairies and lake shores. Some of the habitats do appear to have had a history of light-intensity agriculture, primarily livestock grazing. Given its rarity, S. longipes ssp. longipes was listed as a special concern species in Minnesota in 1984.
Stellaria longipes ssp. longipes is a low-growing perennial that spreads by slender rhizomes to form small to large clumps or mats. The stems range from 3-32 cm (1.2-12.6 in.) tall and are smooth or softly hairy. The leaves are sessile with 1-3 veins including a prominent midrib. They are lanceolate to linear-lanceolate in shape, 0.4-6 cm (0.16-2.4 in.) long and 1-4 mm (0.04-0.16 in.) wide, the margins are entire, and the apex is acute to acuminate. The inflorescence is a terminal cyme with 3-30 flowers. The bracts are lanceolate and 2-10 mm (0.08-0.39 in.) long. The pedicels are ascending to erect, straight, 5-30 mm (0.20-1.18 in.) long, and glabrous or softly hairy. The flowers are 5-10 mm (0.20-0.39 in.) across, and have 5 sepals and 5 petals. Each sepal has 3 veins including a prominent midrib, and is 3.5-5 mm (0.14-0.20 in.) long; the 5 petals are 3-8 mm (0.12-0.31 in.) long (1-1.5 times as long as sepals). The capsules are blackish purple, ovoid to ovoid-lanceoloid, and 4-6 mm (0.16-0.24 in.) long (1.5-2 times as long as sepals) (Chinnappa and Morton 1976; Morton 2005).
Most of the records of S. longipes ssp. longipes in Minnesota are from a general habitat type known locally as brush prairies. There are also records from sandy river banks and lake shores, although these habitats are not as well documented in Minnesota. Soils are consistently sandy, and range from wet to moist or sometimes slightly dryish. The habitats may have scattered trees, primarily Quercus macrocarpa (bur oak) and Populus tremuloides (quaking aspen), as well as Corylus (hazel) and Amelanchier (juneberry) shrubs. The groundcover consists of prairie grasses and forbs that are typical of the region. Within such habitats, S. longipes ssp. longipes may be localized in small openings in the vegetation where competition is reduced. Natural forces that may be responsible for creating such openings could include animal digging (including mound-building ants and pocket gophers) and water erosion associated with seasonal dynamics of lake shores and river banks.
Biology / Life History
From the perspective of pollination, the structure of the flower of S. longipes ssp. longipes is unspecialized and pollination is accomplished by a variety of small flying insects, mainly flies (Chinnappa and Morton 1984). Vegetative reproduction does occur in this species, but apparently serves primarily to enlarge the size of existing clones by the incremental growth of horizontal rhizomes. Clone fragmentation can occur, and will result in an increase in the number of autotrophic individuals, but long-range dispersal is accomplished primarily, if not entirely, by seed. The seeds mature in a capsule that opens and drops the seeds on the ground. The seeds have no specialized structures to aid dispersal and most will likely germinate where they fall. It is also possible that some portion of the seed crop may be dispersed by an unknown animal vector.
Conservation / Management
It seems probable that the long-term survival of S. longipes ssp. longipes in Minnesota will require that large and ecologically varied landforms be managed in such a way as to perpetuate natural ecological processes. Probably not much can be done at the site/microsite level where individual plants are found. Those plants may just be components of a larger metapopulation that is likely maintained by landscape-level ecological processes such as fire, native animal activities, severe storm events, etc.
Conservation Efforts in Minnesota
Most of the known populations of S. longipes ssp. longipes are located on private lands, although one population has been documented in a State Park and another in a Wildlife Management Area. It is not known, however, if management of either of these sites considers the conservation needs of this rare species.
References and Additional Information
Chinnappa, C. C., and J. K. Morton. 1976. Studies on the Stellaria longipes Goldie complex - variation in wild populations. Rhodora 78:488-502.
Chinnappa, C. C., and J. K. Morton. 1984. Studies on the Stellaria longipes Goldie complex (Caryophyllaceae) - biosystematics. Systematic Botany 9(1):60-73.
Morton, J. K. 2005. Stellaria. Pages 96-114 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 5. Oxford University Press, New York, New York.
Penskar, M. R. 2009. Species plant abstract for stitchwort (Stellaria longipes). Michigan Natural Features Inventory, Lansing, Michigan.