Muhlenbergia ligularis (Hack.) Hitchc., Contr. U.S. Natl. Herb. 24(8):388. 1927.

Peterson, Paul M., Herrera Arrieta, Yolanda, Lobo Cabezas, Silvia & Romaschenko, Konstantin, 2023, Taxonomic revision of Muhlenbergia (Poaceae, Chloridoideae, Cynodonteae, Muhlenbergiinae) in Central America: phylogeny and classification, PhytoKeys 230, pp. 1-106 : 1

12. Muhlenbergia ligularis (Hack.) Hitchc., Contr. U.S. Natl. Herb. 24(8):388. 1927.

Fig. 11F-J

Sporobolus ligularis Hack., Oesterr. Bot. Z. 52(2):57. 1902. Type: Ecuador, Pichincha, 23 Jan 1899, Sodiro 23/1 (holotype: W-19160026304 [image!]; isotypes: BAA-2905! ex W, US-3274313! ex W, US-1163183!). Basionym.

= Muhlenbergia calcicola Swallen, Contr. U.S. Natl. Herb. 29(9):407. 1950. Type: Guatemala, Huehuetenango, Chemal, Sierra de los Chuchumatanes, 3300 m, 31 Dec 1940, P.C. Standley 81703 (holotype: US-1910686!; isotypes: F-1200274 [image!], US-2236500US!).

= Muhlenbergia breviculmis Swallen, Contr. U.S. Natl. Herb. 29(9):408. 1950. Type: Guatemala, Huehuetenango, Cerro Chemalito, Sierra de los Cuchumatanes, 3.5 mi W of Santa Eulalia, 3100-3150 m, 2 Aug 1942, J.A. Steyermark 49905 (holotype: US-1935054!; isotypes: F, US-2208654!).

= Muhlenbergia minuscula H. Scholz, Willdenowia 14:393. 1984. Type: Bolivia, Canton Ulla-Ulla, Pampa von Ulla-Ulla, Apolobamba Cordillera, 4450 m, 26 Feb 1983, X. Menhofer X-1974 (holotype: B-10-0249104!; isotype: LPB-0000293 [image!]).

Description.

Loosely tufted annuals to short-lived perennials. Culms 2-12 cm tall, 0.2-0.4 mm diameter just below the panicle, erect or decumbent, slender, glabrous, sometimes flowering the first year, up to 15 cm broad, dying in the center, profusely branched below, a short branchlet with fascicled leaves borne at each node, with 4-6 nodes; internodes 2-20 mm long. Leaf sheaths 2-20 mm long, generally shorter than the internodes, glabrous, ridged, flattened by the densely fascicled branches; ligules 0.6-2.5 mm long, membranous to hyaline, apex truncate to rounded; blades 0.3-2.2 cm long, 0.8-1.5 mm wide, flat or folded, prominently veined, thick, firm, usually with whitish-thickened midvein and margins, conspicuously crystalline or spiculate on both surfaces, otherwise glabrous below, sparsely scaberulous above and along margins, tapering to a boat shaped tip. Panicles 1.0-3.0 cm long, 0.3-1.4 cm wide, long exerted or included in the uppermost sheath, loosely contracted; primary branches 5-9 mm long, one per node, appressed or reflexed at maturity up to 70° from the culm axis; pedicels 1-3 mm long, stiff, densely scabrous, spiculate, erect. Spikelets 1.5-3.0 mm long, often plumbeous to reddish-purple; glumes 1.0-1.9 mm long, subequal, glabrous, apex acute to obtuse, often minutely erose, greenish-gray; lower glumes 1.0-1.7 mm long, 1-veined; upper glumes 1.1-1.9 mm long, 1-veined or occasionally 3-veined; lemmas 1.5-3.0 mm long, lanceolate, 3-veined, keeled, glabrous, mottled with greenish-black areas or dark greenish mottles on a pale background, apex minutely scaberulous, acuminate, entire or mucronate; mucro rarely more than 1(-1.2) mm long; paleas 1.4-2.9 mm long, lanceolate, glabrous; anthers 0.8-1.1 mm long, purplish becoming pale. Caryopses 0.8-1.2 mm long, elliptic to fusiform, brownish.

Distribution.

This species ranges from Guatemala and Costa Rica to Colombia, Venezuela, Ecuador, Bolivia, Peru, and Argentina ( Pohl 1980; Peterson and Annable 1991; Peterson et al. 2001; Giraldo-Cañas and Peterson 2009).

Ecology.

Muhlenbergia ligularis occurs in grassy flats, moist depressions, wet meadows, gravelly banks, ridgetops, and gravelly roadsides often derived from calcareous substrates, associated with Achnatherum , Aciachne , Agrostis , Alnus , Anatherostipa , Baccharis , Berberis , Bidens , Buddleja , Caiophora , Carex , Cenchrus clandestinus (Hochst. ex Chiov.) Morrone, Colletia spinosissima J.F. Gmel., Eleocharis , Festuca , Gaultheria , Hypericum , Jarava , Juncus , Lepidophyllum , Lupinus , Margyricarpus , Muhlenbergia , Nassella , Plantago , Poa , Puya , Rumex , Salvia , and Senecio ; 2320-4650 m.

Comments.

Muhlenbergia ligularis is morphologically similar to the widespread South American, M. fastigiata (J. Presl) Henrard. It can be separated from the latter by possessing flat leaf blades, 0.8-1.5 mm wide, and a rather loosely tufted habit without wiry creeping rootstocks and scaly rhizomes. Morphologically, M. ligularis differs from the Peruvian endemic M. caxamarcensis Lægaard & Sánchez Vega in having glabrous lemmas (sericeous hairs on lower 1/2-3/4 of the lemma in the latter) [ Peterson et al. 2018].

Molecular DNA sequence analysis indicates M. ligularis falls within the M. subg. Bealia clade in a subclade with M. filiformis (Thurb. ex S. Wats.) Rydb. and M. vaginata (Fig. 1 ; Peterson et al. 2021).

Specimens examined.

Costa Rica. San José: Valle de los Conejos (upper Río Talari) and trails to Cerro Chirripó and the Valle de los Lagos, open paramo formation with stands of Chusquea bamboo 1-2.5 m tall on slopes and in the valley, short grasses and very short (30 cm), shrubs on the exposed ridges, W.C. Burger & R.L. Liesner 7470 (CR); Perez Zeledón, Paramo en el Sendero al Valle de los Conejos, E. Alfaro 415 (INB, MO); Perez Zeledon, Rivas, sendero Valle Los Conejos y Cerro Chirripo en Paramo, E. Alfaro 572 (INB); Perez Zeledón, Valle de los Conejos, E. Alfaro 3873 (INB); P. N. Chirripó Alrededores del refugio, parte inferior (sur) del Valle de los Conejos, J. Gómez 5344 (CR); P.N. Chirripó A la vera del Río Talari, parte inferior (Sur) del Valle de los Conejos, J. Gómez 5382 (CR); P.N. Chirripó Valle de los Conejos, R. Ocampo 1500 (CR); Pérez Zeledón, Rivas, A. Rodríguez 6414 (INB); P.N. Chirripó Valle de los Conejos, R. Soto s.n. (CR). Guatemala. Huehuetenango: along road in region of Chémal, Sierra de los Cuchumatanes, at km 36, P.C. Standley 81703 (MO); Sierra de los Cuchumatanes, 6.6 mi NW of Santa Eulalia on road to San Mateo Ixtatán, P.M. Peterson & C.R. Annable 4691 (ARIZ, ENCB, GH. MEXU, MICH, MO, NMC, NY, RSA, TAES, UC, UNLV, US, UTC, WIS, WS); 3.6 mi NW of Paguix on hwy 9N and 16.2 mi S of San Juan Ixcoy, P.M. Peterson & C.R. Annable 4686 (GH, MO, NY, US, WS); 15.1 mi S of San Juan Ixcoy on hwy. 9N, Peterson & Annable 4688 (GH, MO, NY, RSA, US, WS); Meadow at Tojiah on hwy. 9N, P.M. Peterson & C.R. Annable 4695 (GH, MO, NY, RSA, UC, US, WS); 13 mi NW of Santa Eulalia on road to San Mateo Ixtatán, P.M. Peterson & C.R. Annable 4692 (ARIZ, ENCB, GH, MEXU, MICH, MO, NMC, NY, RSA, TAES, UC, UNLV, US, UTC, WIS, WS); Meseta alta Sierra de los Cuchumatanes, R. López s.n., (MO); Cerro Chemalito, Sierra de Cuchumatanes, 3.5 miles W of Santa Eulalia, J.A. Steyermark 49905 (MO); Sierra de los Cuchumatanes, at Chemal at km 318 on Ruta Nacional 9N, J.H. Beaman 3068 ( US); Sierra de los Cuchumatanes, immediately north of Tojiah at km 322 on Ruta Nacional 9N, J.H. Beaman 3920 ( US); Region of Chemal, Sierra de los Cuchumatanes, P.C. Standley 81115 ( US); Sierra de los Cuchumatanes, 3.6 mi NW of Paguix on hwy 9N and 16.2 mi S of San Juán Ixcoy, P.M. Peterson & C.R. Annable 4686 (GH, MO, NY, RSA, US, WS); 15.1 mi S of San Juan Ixcoy on hwy 9N, P.M. Peterson & C.R. Annable 4688 (GH, MO, NY, RSA, US, WS); 6.6 mi NW of Santa Eulalia on road to San Mateo Ixtatán, P.M. Peterson & C.R. Annable 4691 (ARIZ, ENCB, GH, MEXU, MICH, MO, NMC, NY, RSA, TAES, UC, UNLV, US, UTC, WIS, WS); 13 mi NW of Santa Eulalia on road to San Mateo Ixtatán, P.M. Peterson & C.R. Annable 4692 (ARIZ, ENCB, GH, MEXU, MICH, MO, NMC, NY, RSA, TAES, UC, UNLV, US, UTC, WIS, WS); Meadow at Tojiah on hwy 9N, P.M. Peterson & C.R. Annable 4695 (GH, MO, NY, RSA, UC, US, WS); SW of Tojiah on Hwy 9N, P.M. Peterson & C.R. Annable 4700 (NY, US, WS). Chimaltenango: Cerro Chichoy near Chichoy, L.O. Williams & A. Molina R.15317 ( US). Totonicapan: On the Tecum Uman Ridge at km 154 on Ruta Nacional N1, ca 20 km east of Totonicapan, J.H. Beaman 4156 (UC, US); Desconsuelo, potrero natural, Flora alpine, M. de Koninck 116 ( US); Region of Desconsuelo, P.C. Standley 62736 ( US); Region of Chiu Jolom, mountains above Totonicapan, on road to Desconsuelo, P.C. Standley 84418 ( US); Totonicapan, En pastizal dominado por Agrostis exserta y Geranium alpicola , muy sobrepastoreado; plano; plena sol, Smith & Nelson 768 (MO).

Figures

Figure 1. A, B Bayesian tree inferred from combined plastid (ndhA intron, rps 16 - trnK, rps 16 intron, rps 3, and rpl 32 - trnL) and ITS sequences. Thick branches indicate posterior probabilities of 0.95 - 1; species in bold occur in Central America; Scale bar: 2 %.

Figure 11. A-E Muhlenbergia microsperma (DC.) Kunth A habit B inflorescence C ligule D glumes E floret F-J Muhlenbergia ligularis (Hack.) Hitchc. F habit G ligule H glumes I floret J stamens and pistil. A-E drawn from P. M. Peterson 4185 (US, WS) F-J drawn from P. M. Peterson, C. R. Annable, S. Laegaard & R. J. Soreng 12684 (US- 3275569).