29. Muhlenbergia robusta (E. Fourn.) Hitchc., N. Amer. Fl. 17(6): 462. 1935.

Fig. 20A-E

Epicampes robusta E. Fourn., Mexic. Pl. 2:89. 1886. Type: México, Distrito Federal, Santa Fe, 2 Oct 1865, M. Bourgeau 1153 (lectotype: P!, designated by Hitchcock, N. Amer. Fl. 17(6): 462. 1935; isolectotypes: K!, US-999036!, US-999031! fragm., US-90734! fragm.). Basionym.

= Epicampes stricta J. Presl, Reliq. Haenk. 1(4-5):235, t. 39. 1830. Type: México, T. Haenke s.n. (holotype: PRC?; isotypes: LE-TRIN-1558.01! fragm., US-865970! fragm.). ≡ Muhlenbergia presliana Hitchc., N. Amer. Fl. 17(6): 462. 1935b, nom. nov.

= Epicampes berlandieri E. Fourn., Mexic. Pl. 2:89. 1886. Type: México, México, Feb 1839, J.L. Berlandier 670 (lectotype: P! designated by Hitchcock, N. Amer. Fl. 17(6): 462. 1935; isolectotypes: BM-000938652 [image!], G-00099371 [image!], US-1127013!). ≡ Muhlenbergia fournieriana Hitchc., J. Wash. Acad. Sci. 23(10): 453. 1933.

= Epicampes macrotis Piper, Proc. Biol. Soc. Wash. 18:144. 1905. Type: México, Zacatecas, Sierra Madre Mountains, ca. 40 km W of San Juan Capistrano, 7 Aug 1897, J.N. Rose 3528 (holotype: US-302505!). ≡ Muhlenbergia macrotis (Piper) Hitchc., N. Amer. Fl. 17(6): 463. 1935.

= Epicampes minutiflora Mez, Repert. Spec. Nov. Regni Veg. 17:212. 1921. Type: México, Michoacán, near El Canizal, 600m, 15 Jan 1899, E. Langlassé 750 (isotype: US-386160!). ≡ Muhlenbergia meziana Hitchc., N. Amer. Fl. 17(6): 461. 1935, nom. nov.

Description.

Caespitose perennials. Culms 100-230(-300) cm tall, erect, compressed-keeled near base, glabrous to sometimes pubescent below the nodes; internodes glabrous. Leaf sheaths 15-70 cm long, longer than the internodes, glabrous, becoming brownish below, sometimes shredded; sheath auricles present, (1-)2-4(-10) cm long, linear subulate to broadly triangular, longer above, straight or twisted, firm below; ligules 2-10(-12) mm long, membranous, lacerate throughout; blades 40-100 cm long, 4-7 mm wide, folded sometimes involute toward tip, scaberulous above and below, the margins and keel saw-toothed. Panicles 30-80 cm long, (2-)3-8 cm wide, narrow to loosely contracted, greenish-gray to silvery gray or purplish; primary branches 1-15(-17) cm long, naked near base, ascending and closely appressed to spreading up to 40° from the rachises; pedicels 0.3-1.1 mm long, shorter than the spikelets, erect, scaberulous; central axis prominently ribbed, scabrous. Spikelets (1.8-)2-3 (-3.2) mm long, erect, greenish-gray or purplish; glumes 1.8-3.2 mm long, usually longer than the floret, subequal, narrowly oblong to elliptic, veinless to indistinctly 1-veined, hyaline to greenish-gray, glabrous to scaberulous, apex acute to obtuse occasionally erose; lemmas 1.7-2.6 mm long, linear-oblong, unawned or rarely mucronate, greenish to yellowish-brown, glabrous or pubescent with scattered hairs on lower, the hairs up to 0.3 mm long, callus glabrous or with few hairs, apex acute, the mucro when present up to 1 mm long; paleas 1.7-2.6 mm long, glabrous to sparingly pilose between the veins on lower, apex acute; anthers 1.1-2 mm long, purplish. Caryopses 1.2-1.7 mm long, fusiform, brownish. 2 n = 40.

Distribution.

Muhlenbergia robusta occurs in mountainous areas from Sinaloa and Chihuahua south to Chiapas, Guatemala, Honduras, and Nicaragua in Central America (Peterson et al. 2001).

Ecology.

It is found on rocky slopes, along barrancas (canyons), in pine and pine-oak forests, and in tropical deciduous forests; 850-3000 m.

Comments.

Morphologically, M. robusta is similar to M. mutica but can be separated from the latter in having narrow panicles (2-)3-8 cm wide [(8-)15-30 cm wide in M. mutica] and auriculate leaf sheaths (not auriculate in M. mutica), the auricles 2-4(-10) mm long.

In DNA sequence studies, Muhlenbergia robusta is found to align in a large polytomy with other species in M. subg. Trichochloa (Fig. 1; Peterson et al. 2010b; Peterson et al. 2021).

Specimens examined.

Guatemala. Chimaltenango: near finca La Alameda, near Chimaltenango, P.C. Standley 59136 (US); Above Santa Maria, Volcano Agua, A.S. Hitchcock 9129 (US). Guatemala: Guatemala City, 21 km W of Guatemala on CA-1, along road in oak forest, W.E. Harmon& J.A. Fuentes 4865 (MO); Guatemala City, Eureka, A.S. Hitchcock 9081 (US); Guatemala City, A.S. Hitchcock 9035 (US), 9063 (1/2) (US). Huehuetenango: Barranco "Palo Negro" in oak-pine forest about 10 km west of Aguacatan, L.O. Williams et al. 21844 (US), 21848 (US); km 101 between El Mirador and Chintla, Sierra Cuchumatanes, rocky slopes, A. Molina 21176 (US). Santa Rosa: Taxisco, Naranjo, J. Donnell Smith 3932 (US, MO). Quiche: Nebaj, NE of Nebaj, M.J. Metzler 17 (MO). Sacatepequez: near Antigua, P C. Standley 61698 (US); P.C. Standley 76942 (US). Santa Rosa: Taxisco, Naranjo, Heyde & Lux 3932 (MO). Sololá: 5 km W of Patzún, collection from deep ravine covered with pine and oak, W.E. Harmon & J.D. Dwyer 2646 (MO); Cerca del Lago Atitlán, M. de Koninck 145 (US). Honduras. Intibucá: La Esperanza, Intibucá, Cerro San Cristóbal, bosque mixto premontano húmedo, T. M. Mejía O. 87 (MO). Mexico. Chiapas: Camino de San Cristobal a Ocosingo, 31 km suroeste de Ocosingo, R. Banda S. et al. 73117 (DS). Amatenango del Valle: 14 km SE of Teopisca along hwy. to Comitán, G. Davidse et al. 29800 (MO). Angel Albino Corzo: slopes of Río Cuxtepec below Finca Cuxtepec, D.E. Breedlove & G. Davidse 54699 (CAS, MO). Bochil: 5 km east of Bochil on road to Pichucalco, D.E. Breedlove & G. Davidse 55164 (CAS, MO). Comitán de Domínguez: 6 km N of Comitán along Mexican hwy 190, 1770 m, D.E. Breedelove & G. Davidse 54873 (SLPM, CAS, MO); 6 km N of Comitán along Mexican Highway 190, D.E. Breedlove & G. Davidse 54877 (CAS, MO); 6 km N of Comitán along Mexican Highway 190, D.E. Breedlove & G. Davidse 54869 (CAS, MO). Ixtapa: at Escopetazo, D.E. Breedlove & G. Davidse 53948 (CAS, MO); along Mexican Highway 190 at the Zinacantán paraje of Muctajoc, Laughlin 1559 (DS). La Independencia: above and SW of La Soledad on road to Las Margaritas, D.E. Breedlove 53126 (CAS, MO). La Trinitaria: 6-7 km S of La Trinitaria, G. Davidse et al. 29950 (MO); 10 km south of La Trinitaria on Mexican Highway 190, G. Davidse et al. 55070 (CAS, MO). Rayón: 9 miles NW of Pueblo Nuevo Solistahuacá along the road between Rincon Chamula and Rayón, H. Zuill 609 (DS). near summit of Zontehuitz, A. Shilom Ton 30 (DS). Teopizca: 7 km NW of Teopisca along hwy. to San Cristobal de las Casas, G. Davidse et al. 29829 (MO); North of Teopisca, D.E. Breedlove & G. Davidse 54765 (CAS, MO). Tuxtla Gutiérrez: 31 km al W de Tuxtla Gtz y 13 km NE de Chiapa de Corzo, 1050 m, J. C. Soto 13361 con D. Sutton, R. Hampshire, R. Lira y A. Reyes (MEXU); km 11.5 de la carr. Tuxtla Gutierrez-Cañon del Sumidero, en el lugar denominado El Zacabastal, E. Rodríguez s/n (MEXU); 16 km N of Tuxtla Gutiérrez on road to El Sumidero, D.E. Breedlove & B.M. Bartholomew 55491 (CAS, MO). Venustiano Carranza: 3 miles S of Aguacatenango along the road to Pinola Las Rosas, D.E. Breedlove & P.H. Raven 13433 (DS). Villa Corzo: above Colonia Vincente Guerrero on the road to Finca Cuxtepec, D.E. Breedlove & G. Davidse 54600 (CAS, MO); near Revolucion Mexicana, D.E. Breedlove & G. Davidse 54520 (CAS, MO). Zinacantán: near Paraje Sequentic [Zequentic], D.E. Breedlove & G. Davidse 53909 (CAS, MO); Along Mexican Highway 190, 10 miles southeast of the road to Simojovel. Paraje of Granadia, D. E. Breedlove 7274 (DS); at Kampana Ch’en along Mexican Highway 190, 3 miles west of paraje Navenchauk, R.M. Laughlin 2279 (DS); along road from Zinacantán center to Ixtapa near Paraje Vo Bits, D.E. Breedlove 40725 (MO). Nicaragua. Managua: Sierra de Managua, H.A. Garnier 1953 (GH, US).