Muhlenbergia orophila Swallen, Contr. U.S. Natl. Herb.29(9): 408. 1950.

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

20. Muhlenbergia orophila Swallen, Contr. U.S. Natl. Herb.29(9): 408. 1950.

Fig. 15F-J

= Muhlenbergia matudae Sohns, J. Washington Acad. Sci. 46(12): 382, f. 32-38. 1956. Type: México, Morelos, Lago de Zempoala, collected en madera humeda, orilla de bosque mixto de pinos y oyamel, 3000 m, 7 Oct 1951, E. Matuda 25601 (holotype: US-2079186!; isotype: US-2119930!).

Type.

Guatemala, Dept. Huehuetenango, Cerro Chémal in alpine meadow, summit of Sierra de los Cuchumantanes , 3700-3800 m, 8 Aug 1942, J.A. Steyermark 50309 (holotype: F-1202399!; isotypes: F-73211!, G-00099366 [image!], US-132785!, US-132784!, US-1935066!, US-2208672!) .

Description.

Densely caespitose perennials. Culms 12-30 cm tall; leaf sheaths longer than the internodes, glabrous, smooth or scabrous; ligules 0.3-0.5(-1) mm long, apex truncate and erose; blades 5-8 cm long, 1-1.6 mm wide, flat or loosely folded to involute, scaberulous, apearing glabrous below with widely-spaced, stiff, short ascending hairs more common towards the apex, margins scabrous towards apex. Panicles 5-25(-30) cm long, open, diffuse, capillary, the base often partially enclosed by the sheath; primary branches 2-8 cm long, scabrous, naked below with very few spikelets, spreading 60-90° from the culm axis; pedicels 4-15 mm long, straight, scabrous; disarticulation above the glumes. Spikelets 3-3.5 mm long, plumbeous to dark-green turning golden brown with age; glumes 1.5-2.2 mm long, subequal, the lower a little shorter than the upper, 1-veined, apex acute, erose, often mucronate, the mucro less than 0.3 mm long; lemmas 3-3.5 mm long, lanceolate, 3-veined, puberulous, apex acute, minutely bifid, mucronate or awned between the teeth, the awn up 1.3 mm long, straight or slightly curled near apex, scaberulous; callus sparsely hairy; paleas 3-3.6 mm long, often slightly longer than the lemma, 2-veined; anthers about 1.2-1.6 mm long, purple. Caryopses not seen.

Distribution.

This species has been reported in Chiapas and the type was collected in Guatemala ( Villaseñor Ríos 2016). It is also known from central México and has been reported in Ciudad de México, Hidalgo, Morelos, México, Puebla, and Tlaxcala ( Espejo Serna et al. 2000; Villaseñor Ríos 2016; Sanchez-Ken 2018).

Ecology.

Muhlenbergia orophila is found along creeks and wet areas in pine-fir forests; 3000-3860 m.

Comments.

Affinities of M. orophila are unknown and it has not yet been included in a DNA molecular study.

Specimen examined.

Guatemala. Huehuetenango: Chemal, vicinity of Chémal, summit of Sierra de los Cuchumatanes, J.A. Steyermark 50309 (MO).

Figures

Figure 15. A-E Muhlenbergia quadridentata (Kunth) Trin. A habit B ligule C glumes D floret E stamens, pistil, and lodicules F-J Muhlenbergia orophila Swallen F habit G ligule H glumes I floret J stamens, pistil, and lodicules. A-E drawn from P. M. Peterson & C. R. Annable 6201 (US) F-J drawn from P. M. Peterson & C. R. Annable 11105 (US).