Muhlenbergia macroura (Kunth) Hitchc., N. Amer. Fl. 17(6): 468. 1935.

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

13. Muhlenbergia macroura (Kunth) Hitchc., N. Amer. Fl. 17(6): 468. 1935.

Fig. 7A-E

Crypsis macroura Kunth, Nov. Gen. Sp. (quarto ed.) 1: 140-141. 1816 Type: México. Toluca, in apricis montanis regio Mexicane, 1760 m, F.W.H.A. Humboldt & A.J.A. Bonpland s.n. (holotype: P-00669403[image!]; isotypes: BAA-00003297 [image!], P-00077291 [image!]). ≡ Cinna macroura (Kunth) Kunth, Révis. Gramin. 1: 67. 1829. ≡ Phleum macrourum (Kunth) Willd. ex Steud., Nomencl. Bot. (ed. 2) 1: 365. 1840. ≡ Epicampes macroura (Kunth) Benth., J. Linn. Soc., Bot. 19: 87. 1881. ≡ Crypsinna macroura (Kunth) E. Fourn., Mexic. Pl. 2: 90. 1886. Basionym.

Description.

Caespitose perennials. Culms 75-200 cm tall, erect, terete near base, forming dense clumps of 100 culms or more and up to 1 m in diameter, pubescent below the nodes, usually 1 or 2 nodes per culm; internodes mostly glabrous. Leaf sheaths 15-40 cm long, shorter than the internodes, glabrous to scaberulous, the basal persistent and keeled with age; ligules (5-)8-40(-50) mm long, strongly decurrent, splitting into broad auricles 10-35(-50) mm long, membranous to chartaceous above, brownish, firm, the veins evident below and near margins, apex truncate to obtuse; blades 20-60 cm long, 2-5 mm wide, mostly flat and apically involute, scabrous above and below. Panicles (15-)20-40 cm long, 5-12 mm wide, dense, spikelike, erect, exserted and surpassing the blades in height, greenish to greenish-gray; primary branches 0.1-1.2 cm long, ascending and tightly appressed, unexposed, imbricate; pedicels 0.1-1.7 mm long, shorter than the spikelets, scaberulous to hispidulous. Spikelets 3.4-5.6(-6) mm long, erect, strongly laterally compressed, greenish-gray; glumes 3.4-5.6 mm long, linear-elliptic to linear-ovate, usually longer than the lemma, 1-veined, scabrous along the keel, subequal, awnless, the upper slightly longer, apex acute to acuminate, scabrous; lemmas 3.4-5 mm long, elliptic to linear-elliptic, scabrous, greenish-gray; callus pilose, the hairs 0.1-0.3 mm long, apex acute, rarely mucronate, the mucro less than 0.4 mm long; paleas 3.4-5 mm long, about as long as the lemma, scabrous, apex acute; anthers 1.5-2.2 mm long, pale greenish. Caryopses 2-3 mm long, fusiform, brownish. 2 n = 20, 24, 28.

Distribution.

Muhlenbergia macroura occurs in the Sierra Madre Occidental in northern México from Chihuahua to Chiapas and Guatemala (Herrera Arrieta and Peterson 2018).

Ecology.

This species can be found growing on upland slopes, mountain meadows, in pine or pine-oak forests often in deep humid soils; 1500-3400 m.

Comments.

Muhlenbergia macroura is morphologically similar to M. nigra but differs in having spikelets 3.4-5.6(-6) mm long [(5.5-)6-8 mm long in M. nigra ] and greenish to greenish-gray panicles (15-)20-40 cm long [dark green to blackish panicles 6-15(-17) cm long in M. nigra ]. Muhlenbergia macroura is a member of M. subg. Trichochloa , and in a recent study was found to be sister to M. rigida ( Peterson et al. 2021).

Specimens examined.

Guatemala. Chimaltenango: Plains near Tecpam, A.F. Skutch 610 (US). Guatemala: Guatemala City, A.S. Hitchcock 9140 (US). Huehuetenango: La Sierra (Tujimach), across river from San Juan Atitlan, Sierra de los Cuchumatanes, J.A. Steyermark 51968 (US); Paquix, San Juan Ixcoy , Sierra de los Cuchumatanes between Paquix and San Juan Ixcoy, A.A. Molina et al. 30017 (MO); San Juan Ixcoy , Sierra de los Cuchumatanes, along road to Huehuetenango, 5 miles S of San Juan Ixcoy, D.E. Breedlove 8569 (MO, DS); San Juan Ixcoy , Jolomhuitz, Aldea Jolomhuitz, M. Véliz 95.4470 (MO). Quetzaltenango: Mountains near Santa Maria, near Quetzaltenango, Weatherwax 177 (US); La Esperanza, M. de Koninck 18 (US); Cuesta El Caracol, Sierra Madre Mountains , about 5-8 km N of San Juan Ostuncalco, L.O. Williams et al. 22770 (US); Oak pine forest, above Los Vahos, Cerro Quemado, P.C. Standley 86171 (US). Quiche: Chichicastenango , 1 km N of Chichicastenango, W.E. Harmon 4369 (MO). Sacatepequez: Santa Maria de Jesus , Mal Paso, Volcan de Agua , Mal Paso, M. Véliz et al. 8529 (MO); Volcan Agua, W.A. Kellerman 4764 (US). San Marcos: Tajumulco, Volcan Tajumulco, M. Véliz et al. 10622 (MO), M. Véliz et al. 10638 (MO); El Boqueron, in the mountains at the summit of the road between San Antonio Sacatepequez and Palestina, P.C. Standley 85307 (US). Solola: Volcan Atitlan, near summit of mountain, J. H. Beaman 4053 (US); NW of Los Encuentros, L.O. Williams, A. Molina R. & T.P. Williams 25404 (F, US). Totonicapán: near San Francisco El Alto , P.C. Standley 83123 (US); along road between San Francisco El Alto and Momostenango, P.C. Standley 84011 (US); O. F. Cook 35 (US); Hochland von Calel, s.n. 2703 (US). Mexico. Chiapas: Vol. Tacana, Chiquihuite, E. Matuda 2829 (ARIZ, MO); Mt. Tacana , E. Matuda 2420 (DS). Amecatlán, Paraje Navenchauk, along mexican Hwy 190, R. M. Laughin 1506 (ENCB). La Grandeza: La Grandeza to Ojo de Agua , E. Hernandez X-1445 (US). Larráinzar: Muctahuitz. Region Los Altos, L. Soto s/n (MEXU). Motozintla: On the N and W slope of Cerro Mozotal below the microwave tower along the road from Huixtla to El Porvenir and Siltepec, D.E. Breedlove & R.F. Thorne 31173 (MO). San Juan Chamula: near school house of yal Ichin, D.E. Breedlove 7147 (ENCB, DS); Yut Bax, C. Santoz Ruíz 179 (ENCB). Motozintla, NW slope of cerro Mozotal, along the road from Huixtla to El Porvenir and Siltepec, D.E. Breedlove 31175 (NY); Slope near the school house of Yal Ichin, D.E. Breedlove 10471 (DS). Tenajapa: Paraje Matsbad, Alush Shilon Ton 999, (ENCB, DS); Paraje Shohieh, Alush Shilon Ton 548 (ENCB, DS); near Tenejapa Center, Alush Shilon Ton 63 (DS). Venustiano Carranza: Ejido "Laja Tendida" km 17 carr. Venustiano Carranza-Tuxtla Gutiérrez, aprox. 2 km a Flores Magón, A. Miranda S. s/n (MEXU). Zinacantán: near Paraje Nachij [Nachig], D.E. Breedlove & G. Davidse 53871 (CAS, MO); Steep NE slope of Zontehuitz near Summit, D.E. Breedlove 12348 (DS); near Zinacantán Center, R.M. Laughlin 2241 (DS); at paraje Navenchauk along Mexican Highway 190, R.M. Laughlin 1506 (DS); alley floor in Zinacantán Center, R.M. Laughlin 630 (DS) .

Figures

Figure 7. A-E Muhlenbergia macroura (Kunth) Hitchc. A habit B ligule C glumes D floret E stamens, pistil, and lodicules F-I Muhlenbergia distichophylla (J. Presl) Kunth F ligule G glumes H floret I stamens pistil, and lodicules. A-E drawn from P. M. Peterson & C. R. Annable 5970 (US) F-I drawn from L. O. Williams, A. Molina R. & T. P. Williams 22309 (US) and F. W. Gould 12666 (US).