Muhlenbergia Schreb., Gen. Pl. 1: 44. 1789.

Dilepyrum Michx., Fl. Bor.-Amer. 1: 40. 1803. Type: Dilepyrum minutiflorum Michx. (= Muhlenbergia schreberi J. F. Gmel.). ( M. subg. Muhlenbergia).

Aegopogon Humb. & Bonpl. ex Willd., Sp. Pl. 4 (2): 899. 1805 [1806]. Type: Aegopogon cenchroides Humb. & Bonpl. ex Willd. [≡ Muhlenbergia cenchroides (Humb. & Bonpl. ex Willd.) P.M. Peterson]. ( M. subg. Muhlenbergia).

Podosemum Desv., Nouv. Bull. Sci. Soc. Philom. Paris 2: 188. 1810. Type: Podosemum capillare (Lam.) Desv. [≡ Muhlenbergia capillaris (Lam.) Trin.]. ( M. subg. Trichochloa).

Clomena P. Beauv., Ess. Agrostogr. 28. 1812. Type: Clomena peruviana P. Beauv. [≡ Muhlenbergia peruviana (P. Beauv.) Steud.]. ( M. subg. Clomena).

Tosagris P. Beauv., Ess. Agrostogr. 29. 1812. Type: Tosagris agrostidea P. Beauv. [= Muhlenbergia capillaris (Lam.) Trin.]. ( M. subg. Trichochloa).

Trichochloa P. Beauv., Ess. Agrostogr. 29. 1812. Type: Trichochloa purpurea P. Beauv. [= Muhlenbergia expansa (Poir.) Trin.]. ( M. subg. Trichochloa).

Podosaemum Kunth, Mem. Mus. Hist. Nat. 2: 72. 1815; orth. var. Muhlenbergia purpurea Podosemum . ( M. subg. Trichochloa).

Hymenothecium Lag., Gen. Sp. Pl. 4. 1816. Lectotype: Cynosurus tenellus Cav. ex DC., designated by Hitchcock 1920: 169 [≡ Lamarckia tenella DC. ≡ Hymenothecium tenellum (Cav. ex DC.) Lag. = Muhlenbergia uniseta (Lag.) Columbus]. ( M. subg. Muhlenbergia).

Lycurus Kunth, Nov. Gen. Sp. 1: 141. 1815 [1816]. Lectotype: Lycurus phleoides Kunth, designated by Hitchcock 1920: 139 [≡ Muhlenbergia phleoides (Kunth) Columbus]. ( M. subg. Pseudosporobolus).

Anthipsimus Raf., J. Phys. Chim. Hist. Nat. Arts 89: 105. 1819. Type: Anthipsimus gonopodus Raf. (= Muhlenbergia schreberi J.F. Gmel.). ( M. subg. Muhlenbergia).

Sericrostis Raf., Neogenyton 4. 1825. Lectotype: Stipa sericea Michx, designated by Pfeiffer 1874: 1142 [≡ Muhlenbergia sericea (Michx.) P.M. Peterson]. ( M. subg. Trichochloa).

Pereilema J. Presl, Reliq. Haenk. 1 (4-5): 233.1830. Type: Pereilema crinitum J. Presl (≡ Muhlenbergia pereilema P.M. Peterson). ( M. subg. Muhlenbergia).

Epicampes J. Presl, Reliq. Haenk. 1 (4-5): 235. 1830. Type: Epicampes stricta J. Presl [= Muhlenbergia robusta (E. Fourn.) Hitchc.]. ( M. subg. Trichochloa).

Dactylogramma Link, Hort. Berol. 2: 248. 1833. Type: Dactylogramma cinnoides Link [= Muhlenbergia glomerata (Willd.) Trin.]. ( M. subg. Muhlenbergia).

Calycodon Nutt., Proc. Acad. Nat. Sci. Philadelphia 4: 23. 1848. Type: Calycodon montanum Nutt. [≡ Muhlenbergia montana (Nutt.) Hitchc.]. ( M. subg. Clomena).

Pleopogon Nutt., Proc. Acad. Nat. Sci. Philadelphia 4: 25. 1848. Type: Pleopogon setosum Nutt. [≡ Lycurus setosus (Nutt.) C.G. Reeder = Muhlenbergia alopecuroides (Griseb.) P.M. Peterson & Columbus]. ( M. subg. Pseudosporobolus).

Schedonnardus Steud., Syn. Pl. Glumac. 1: 146. 1854. Type: Schedonnardus texanus Steud. [= Lepturus paniculatus Nutt. ≡ Rottboellia paniculata (Nutt.) Spreng. ≡ Schedonnardus paniculatus (Nutt.) Branner & Coville ≡ Spirochloe paniculata (Nutt.) Lunell ≡ Muhlenbergia paniculata (Nutt.) Columbus]. ( M. subg. Pseudosporobolus).

Vaseya Thurb., Proc. Acad. Nat. Sci. Philadelphia 15: 79. 1863. Type: Vaseya comata Thurb. [= Muhlenbergia andina (Nutt.) Hitchc.]. ( M. subg. Muhlenbergia).

Chaboissaea E. Fourn., Mexic. Pl. 2: 112. 1886. Type: Chaboissaea ligulata E. Fourn. [≡ Muhlenbergia ligulata (E. Fourn.) Scribn. & Merr.]. ( M. subg. Pseudosporobolus).

Crypsinna E. Fourn., Mexic. Pl. 2: 90. 1886. Lectotype: Crypsis macroura Kunth, designated by Hitchcock 1920: 144. [≡ Crypsinna macroura (Kunth) E. Fourn.≡ Muhlenbergia macroura (Kunth) Hitchc.]. ( M. subg. Trichochloa).

Redfieldia Vasey, Bull. Torrey Bot. Club 14: 133. 1887. Type: Graphephorum flexuosum Thurb. ex A. Gray [≡ Redfieldia flexuosa (Thurb. ex A. Gray) Vasey ≡ Muhlenbergia multiflora Columbus]. ( M. subg. Pseudosporobolus).

Bealia Scribn., True Grasses 104, f. 45a. 1890. Type: Bealia mexicana Scribn. (≡ Muhlenbergia biloba Hitchc.). ( M. subg. Bealia).

Blepharoneuron Nash, Bull. Torrey Bot. Club 25(2): 88. 1898. Lectotype: Vilfa tricholepis Torr., designated by Peterson and Annable 1990: 522 [≡ Blepharoneuron tricholepis (Torr.) Nash ≡ Muhlenbergia tricholepis (Torr.) Columbus]. ( M. subg. Bealia)

Schaffnerella Nash, N. Amer. Fl. 17(2): 141. 1912. Type: Schaffnera gracilis Benth. [≡ Schaffnerella gracilis (Benth.) Nash ≡ Muhlenbergia spatha Columbus]. ( M. subg. Pseudosporobolus).

Description.

Plants annual or perennial; usually synoecious, infrequently andromonoecious; sometimes rhizomatous, often cespitose, sometimes mat-forming, rarely stoloniferous. Culms 2-300 cm, erect, geniculate, or decumbent, usually herbaceous, sometimes becoming woody. Sheaths open; ligules membranous or hyaline (rarely firm or coriaceous), acuminate to truncate, sometimes minutely ciliolate, sometimes with lateral lobes longer than the central portion; blades narrow, flat, folded, or involute, sometimes arcuate. Inflorescences (synflorescence) terminal, sometimes also axillary, open to contracted, racemelike or spikelike panicles; disarticulation usually above the glumes, occasionally below the pedicels. Spikelets mostly perfect with 1 (2-6) florets, sometimes staminate or sterile, occasionally paired or in groups of threes then the central spikelet perfect and the lateral ones staminate or sterile; chasmogamous, rarely cleistogamous; glumes usually (0)1(2-3)-veined, apices entire, erose, or toothed, truncate to acuminate, sometimes mucronate or awned from the midvein, occasionally awned from the lateral veins; lower glumes sometimes rudimentary or absent, occasionally bifid; upper glumes shorter than to longer than the florets; callus es poorly developed, glabrous or hairy, the hairs up to 3.5 mm long, straight; lemmas glabrous, scabrous, or with short hairs, 3-veined (rarely appearing 5-veined), apices awned from the midvein, mucronate, or unawned; awns, if present, straight, flexuous, sinuous, or curled, sometimes borne between 2 minute teeth, lateral veins occasionally extended into awns; paleas shorter than or equal to the lemmas, 2-veined, apices; lodicules 2, cuneate, fleshy, sometimes with a narrow membranous apex, apex truncate and slightly lobed, glabrous; anthers (1-2) 3, purple, orange, yellow, olivaceous, or whitish; ovary with 2 styles (rarely 1), glabrous, stigmas plumose. Caryopses an achene,elongate, fusiform or elliptic, slightly dorsally compressed, rarely laterally compressed, free threshing; grain solid without lipid. Cleistogamous panicles sometimes present in the axils of the lower cauline leaves, enclosed by a tightly rolled, somewhat indurate sheath. Chromosome base number is x = (8 or 9) 10, and these are relatively small in size when compared to chromosomes in the Pooideae .

Distribution.

The genus is primarily distributed in the Western Hemisphere in North, Central, and South America (Peterson 2003; Peterson and Giraldo-Cañas 2012; Peterson et al. 2018, 2021). There are also eight species known to occur in southeastern Asia; six of these are found in China (Wu and Peterson 2006) and five in India (Tiwari et al. 2023).

Ecology.

The species occur in open habitats in deserts, grasslands, sclerophyllous scrubland, and margins of forests often in xeric to meso-xeric habitats from near sea level to more than 4000 m.

Etymology.

Named for Gotthilf Henry Ernest Muhlenberg (1753-1815), a Lutheran minister and pioneer botanist of Pennsylvania, USA.