Rare Species Guide

  Synonyms

Avenella flexuosa

  Basis for Listing

Deschampsia flexuosa (slender hair grass) is locally common in parts of eastern North America but gets more rare going westward and northward; in Minnesota it is quite rare (Barkworth 2007). It has been documented only seven times in the state, and most of the records are from an 8-mile area along the shore of Lake Superior between Grand Portage and Pigeon Point in northeastern Cook County. The other two records are from central Cook County near Grand Marais and Minnesota Point in St. Louis County. The Minnesota Point and Pigeon Point collection sites are at the extreme eastern and western extent of Lake Superior shoreline in Minnesota, a distance of about 241 km (150 mi.) (North Shore Highlands Subsection). For reasons not entirely understood, similar habitats in the intervening areas do not support populations of this species.

When this species was listed as special concern in Minnesota in 1984, the status of threatened was considered, but it was thought prudent to wait until a more comprehensive field survey could be undertaken. Such a survey was subsequently completed by the Minnesota Biological Survey, and only one additional population of D. flexuosa was found, far fewer than was hoped for. For this reason, its status was changed to threatened in 2013.

  Description

The stems of D. flexuosa grow in dense clumps and reach a maximum height of about 80 cm (2.6 ft.). The leaves occur primarily on the lower half of the stem and are 12-25 cm (4.7-9.8 in.) long. They are very slender and strongly inrolled (hair-like), only 0.3-0.5 mm (0.012-0.020 in.) across; the ligule is 1.5-3.6 mm (0.06-0.14 in.) long and rounded to acute at the tip. The inflorescence is a loose few-flowered panicle, 5-15 cm (2.0-5.9 in.) long and 4-12 cm (1.6-4.7 in.) wide. The spikelets occur near the ends of the panicle branches and contain 2 flowers each. In each spikelet, the glumes are shorter or slightly longer than the upper flower, and they have 1 vein and an acute tip. The lemmas are 3.3-5.0 mm (0.13-0.20 in.) long and have a long twisted awn that originates near the base of the lemma and protrudes from the spikelet (Barkworth 2007).

  Habitat

In Minnesota, D. flexuosa occurs in dry, sandy or rocky soil, often under or in association with pine forests. It has also been found in very sunny openings on rocky substrates within forests. All of the known locations of D. flexuosa, except for one, are near the shore of Lake Superior, which presumably influences habitat suitability in some way.

  Biology / Life History

There are few detailed studies that describe the biology of wild populations of D. flexuosa in North America; that said, a few generalizations can be safely gleaned from the published literature. For example, the narrow inrolled leaves of D. flexuosa are characteristic of species that are adapted to dry and droughty soils or arid climates. Also, the structure of the flower indicates wind-pollination, and the awn on the lemma (seed) is probably intended to snag in animal fur, thereby facilitating seed dispersion. Fidelity to low nutrient and acidic soil has also been reported, and D. flexuosa may tolerate a certain amount of soil disturbance (Scurfield 1954). Although D. flexuosa is associated with forests, it seems to do fine along a partially shaded forest edge or under openings in the canopy.

  Conservation / Management

Because so little is known about the population dynamics and ecological needs of D. flexuosa in Minnesota, management objectives ought to be conservative and emphasize the maintenance of current habitat conditions. In particular, disturbance to the substrate should be minimized to prevent the invasion of non-native plant species. Also, significant alterations to the tree canopy should be avoided in order to maintain the current light regime.

  Best Time to Search

The best time to search for D. flexuosa is when the flowers are fully developed, from July through mid-September.

  Conservation Efforts in Minnesota

The three general areas where D. flexuosa has been found in Minnesota (Minnesota Point, Grand Marais, and Grand Portage) include tribal land, U. S. Forest Service land, and municipal land. The population on municipal land is small and threatened by increasing development pressures and recreational activities, though it may also extend onto an adjacent Scientific and Natural Area, which offers greater protection. None of the populations are currently being monitored.

  Authors/Revisions

Welby Smith (MNDNR), 2008 and 2018

(Note: all content ©MNDNR)

  References and Additional Information

Barkworth, M. E. 2007. Deschampsia. Pages 624-633 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 24. Oxford University Press, New York, New York.

Butters, F. K., and E. C. Abbe. 1953. A floristic study of Cook County, northeastern Minnesota. Rhodora 55:21-55.

Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.

Lakela, O. 1965. A flora of northeastern Minnesota. University of Minnesota Press, Minneapolis, Minnesota. 541 pp.

Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.

Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 320 pp.

Scurfield, G. 1954. Biological Flora of the British Isles: Deschampsia flexuosa (L.) Trin. Journal of Ecology 42:225-233.