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Muhlenbergia minutissima

(Steud.) Swallen

Least Muhly

G5Secure Found in 3 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.161112
Element CodePMPOA48130
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderCyperales
FamilyPoaceae
GenusMuhlenbergia
Other Common Names
annual muhly (EN)
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2024-07-09
Change Date1990-02-15
Edition Date2024-07-09
Edition AuthorsN. Ventrella (2024)
Threat ImpactUnknown
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Number of Occurrences81 to >300
Rank Reasons
Muhlenbergia minutissima is an annual grass that occurs in sandy and gravelly drainages, road cuts, slopes, flats, and open areas in pine forests, pinyon-juniper woodlands, scrub forests, and savannahs in western North America from Washington east to South Dakota, south to Texas, and west to California in the United States, and into southern Mexico. Threats to this species likely include development, road maintenance, invasive species, livestock grazing, and drought. However, with a large range extent, 200-300+ occurrences, and broad habitat preferences for abundant habitat, this species is considered secure.
Range Extent Comments
Muhlenbergia minutissima occurs in western North America from Washington east to South Dakota, south to Texas, and west to California in the United States, and into southern Mexico (FNA 2003). Range extent was estimated to be over 3 million square kilometers using herbarium specimens and photo-based observations documented between 1993 and 2024 (GBIF 2024, iNaturalist 2024, SEINet 2024).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens and photo-based observations documented between 1993 and 2024, it is estimated that there are over 200 occurrences rangewide (GBIF 2024, iNaturalist 2024, SEINet 2024). However, given that there are minimal herbarium records, low collection effort due to perceived and real identification challenges, and limited annotations to affirm identifications of existing specimens, this estimate is certainly not representative of the species true abundance.
Threat Impact Comments
Although threats are not widely documented, this species is potentially threatened by development, road maintenance, invasive species, livestock grazing, drought, and other threats in some places. However, their overall impact is unknown.
Ecology & Habitat

Description

Minute muhly is a tufted annual grass with stems up to 3 dm (1 ft) tall. The inrolled leaf blades are 1-2 mm wide, and the membranous ridge onthe blade where it meets the stem (ligule) is 1-3 mm high with jagged margins. Plants are sparsely hairy below stem nodes and on upper leaf surfaces. The single-flowered spikelets, ca. 1 mm long, are borne on the ends of long ascending stalks in an open, terminal inflorescence that is often half the plant's total height. The glumes are sparsely hairy along the margins and sometimes on the back, and both the glumes and lemmas lack awns.

Diagnostic Characteristics

This is our only annual Muhlenbergia with an open,spreading inflorescence. It could be confused with species of Panicum and Agrostis. A technical key and a hand lens or microscope are needed for positive determination.

Habitat

Muhlenbergia minutissima occurs in "sandy and gravelly drainages, rocky slopes, flats, road cuts, and open sites. It is usually found in yellow pine and oak-pine forests, pinyon-juniper woodlands, thorn-scrub forests, and oak-gramma savannahs" (FNA 2003).
Terrestrial Habitats
Forest/WoodlandForest - ConiferForest - MixedForest EdgeWoodland - ConiferSavanna
Other Nations (1)
United StatesN5
ProvinceRankNative
ColoradoS3Yes
IdahoSNRYes
South DakotaSNRYes
NebraskaS1Yes
WashingtonSNRYes
TexasS1Yes
New MexicoSNRYes
CaliforniaSNRYes
OregonS2Yes
MontanaS3Yes
NevadaS2Yes
UtahS1Yes
ArizonaSNRYes
WyomingS2Yes
Threat Assessments
ThreatScopeSeverityTiming
Unknown/undetermined———

—

Plant Characteristics
DurationANNUAL
Economic Value (Genus)No
Roadless Areas (3)
New Mexico (3)
AreaForestAcres
Chama WS RiverSanta Fe National Forest4,168
Elk MountainGila National Forest6,550
T BarGila National Forest6,823
References (5)
  1. Flora of North America Editorial Committee, ed. 2003. Flora of North America, north of Mexico. Volume 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford Univ. Press, New York. 783 pp.
  2. Global Biodiversity Information Facility (GBIF). 2024. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2024).
  3. iNaturalist. 2024. Online. Available: https://www.inaturalist.org (accessed 2024).
  4. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  5. Southwest Environmental Information Network (SEINet). 2024. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2024).