Muhlenbergia plumiseta Columbus, Aliso 28: 66. 2010.

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

25. Muhlenbergia plumiseta Columbus, Aliso 28: 66. 2010.

Fig. 16 G-L

Pereilema ciliatum E. Fourn., Mexic. Pl. 2: 93. 1886. Type: México, region Orizaba, 8 Nov 1866, E. Bourgeau 3328 (lectotype, designated here: P-00751680!; isolectotypes: K-000308948 [image!], L-0062312 [image!], MPU-026837 [image!], US-996083!). ≡ Muhlenbergia plumosa P. M. Peterson, Amer. J. Bot. 97(9): 1546. 2010, isonym. Basionym.

Description.

Delicate, caespitose, annuals. Culms 15-50 cm tall, decumbent, rooting at the lower nodes, smooth and glabrous below the nodes; internodes usually glabrous to scaberulous. Leaf s heaths shorter than the internodes, scaberulous or smooth; ligules 0.2-0.4 mm long, membranous, apex truncate, erose; blades 4-10 cm long, 1.5-3 mm wide, flat, acuminate, auriculate near base, the auricles 0.5-1 mm long, clasping, ciliate. Panicles (2-)3-8 cm long, 0.2-0.6 cm wide, spiciform, linear, continuous; primary branches 0.2-0.8 cm long, tightly appressed, pilose, ascending, frequently glandular, the spikelets arising just above the sterile spikelets or bristles, the bristles 1-4 mm long, plumose, deciduous; pedicels 0.1-0.2 mm long, arising just above the bristles. Spikelets 2-3 mm long, stramineous to mottled with gray areas, subtended by an involucre of deciduous bristles; glumes 1-3 mm long, narrowly awl-shaped, 1-veined, plumose, difficult to separate from the bristles; lemmas (1.8-)2-3 mm long, lanceolate, scabrous, 3-veined, usually awned, the awns (1-)5-25 mm long, straight or flexuous, callus hairy, the hairs 0.2-0.4 mm long; paleas (1.8-)2-3 mm long, as long as the lemmas, apex bidentate; stamens 3, anthers 0.6-1.4 mm long, yellow or purplish; styles 2. Caryopses about 0.8 mm long, ovoid. 2 n = 40 ( Reeder 1968).

Distribution.

Muhlenbergia plumiseta ranges from northwestern México to Guatemala and El Salvador ( Peterson et al. 2001).

Ecology.

This species occurs on open hillsides, ravines, and margins of forests in tropical deciduous forests and pine forests in shaded, often dry sites; 700-1800 m.

Comments.

Muhlenbergia plumiseta can be separated from M. pereilema in having deciduous, plumose bristles (bristles not plumose in M. Pereilema ) subtending the spikelets and spiciform panicles (2-)3-8 cm long, 0.2-0.6 cm wide (10-22 cm long, 1-3 cm wide in M. Pereilema ) [ Herrera Arrieta et al. 2010). This species forms a clade with M. Beyrichiana and M. Pereilema within M. Subg. Muhlenbergia ( Peterson et al. 2021).

Specimens examined.

Guatemala. Huehuetenango: Rio Selgua , from wooded slopes above Río Selegua, W.E. Harmon & J.D. Fuentes 4807 (MO) . Mexico. Chiapas: Chiapa de Corzo: above El Chorreadero, D.E. Breedlove 53812 (CHAPA). Chicoasén: Mirador "Manos que imploran", 10 km al SW de Chicoasén, A. Reyes G. 911 (MEXU). Jitotol: 3 km NE de Jitotol, en la carr. 195, F.W. Gould 12707 (ENCB, MEXU, US). Ocozocoautla de Espinosa: 14.8 mi de Ocozocoautla, en la carr. Méx., J. Brunker & C. Perino 314 (ENCB). Tenejapa: Paraje de Kotol Te' , D.E. Breedlove 7363 (ENCB, US). Tuxtla Gutiérrez: 2 mi S of Tuxtla Gutiérrez along road to Villa Flores, D.E. Breedlove & P.H. Raven 13334 (US); 11 km al NE de Tuxtla Gutierrez, Cañon del Sumidero, R. Torres, E. Cabrera & M. Huft 6348 (MEXU); 17 km al NE de Tuxtla Gutierrez, Cañon del Sumidero, R. Torres, E. Cabrera & M. Huft 6405 (MEXU). Zinacantán: along Mexican Hwy 190 at paraje Sequentic, D.E. Breedlove 28688 (MEXU) .

Figures

Figure 16. A-F Muhlenbergia pereilema P. M. Peterson A habit B ligule with auricles C portion of the inflorescence D glumes E floret F stamens, pistil, and lodicules G-L Muhlenbergia plumiseta Columbus G habit H ligule with auricles I portion of the inflorescence J bristles K floret L stamens and pistil. A-F drawn from A. S. Hitchcock 9050 (US) G-L drawn from C. G. Pringle 5962 (US).