Muhlenbergia expansa (Poiret) Trinius. Savanna Hairgrass. Phen: Sep-Oct. Hab: Pine savannas, pine flatwoods, mesic areas in sandhill-pocosin ecotones. Dist: Se. VA south to FL, west to e. TX (nearly exactly the range of Pinus palustris).

ID notes:Muhlenbergia expansa can be distinguished in sterile condition from other savanna bunchgrasses (Sporobolus teretifolius, S. pinetorum, S. floridanus, S. curtissii, Aristida stricta, and A. beyrichiana) by the following characteristics: old leaf bases fibrous and curly (rather than hardened and cartilaginous) and ligules 1-3 mm long (rather than 0.2 to 0.5 mm long). The open panicle somewhat resembles that of several species of similar habitat which often co-occur with M. expansa – Sporobolus teretifolius, S. pinetorum, S. curtissii, S. floridanus, and S. brevipilis, but the panicle of M. expansa is capillary, flexuous, and fragile, tending to break up over the winter (vs. fine-textured but not capillary, the branches rigid and ascending, more likely to persist over the winter in relatively intact condition). The vegetative characters listed above and under Sporobolus brevipilis are also useful.

Origin/Endemic status: Endemic

Taxonomy Comments: See M. capillaris for a discussion of recent studies on the M. capillaris complex.

Other Comments: An important part of the grassy component of many longleaf pine savannas, M. expansa’s flowering is stimulated by fire, and, lacking fire, it may be found in large populations in solely vegetative condition.

Synonymy: = ETx1, F, FNA25, GW1, HC, K3, K4, RAB, S, Va, Gustafson & Peterson (2007); = Muhlenbergia capillaris (Lam.) Trin. var. trichopodes (Elliott) Vasey – C, K1, WH3, Morden & Hatch (1989); = Muhlenbergia trichopoides (Elliott) Chapm. – S13; < Muhlenbergia capillaris (Lam.) Trin. – Tx; < Muhlenbergia sericea (Michx.) P.M.Peterson – FlGr

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FACW
• Eastern Mountains and Piedmont: FACW
• Great Plains: FACW
• Northcentral & Northeast: FACW

Heliophily: 9