Muhlenbergia flabellata Mez, Repert. Spec. Nov. Regni Veg. 17: 213. 1921.

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

9. Muhlenbergia flabellata Mez, Repert. Spec. Nov. Regni Veg. 17: 213. 1921.

Fig. 9A-E

Type.

Costa Rica, San José, Cerro de Buena Vista , 3000m, 19 Jan 1891, H. Pittier 3372 (lectotype, designated here: G-00192109 [image!]; isolectotypes G-00192054 [image!], US-577110!) .

Description.

Caespitose and sprawling perennials. Culms 25-45 cm long, densely branched near base, decumbent and rooting below; internodes glabrous. Leaf sheaths much overlapping, flabellately arranged, glabrous, margins membranous, old sheaths flattened and papery; ligules (2.5-)3-8 mm long, membranous, hyaline, margins entire, decurrent, apex acute; blades 2-5 cm long, 1-2 mm wide, flattened to folded or involute, mainly basal, strongly ridged above with short stiff hairs, scabrous below. Panicles 3-9(-15) cm long, 2-3 cm wide, few-flowered, narrow, short-exserted, dark green; primary branches mostly 1-2 cm long, sometimes purplish with loosely appressed and ascending branches, spreading up to 30° from the culm axis, central axis slightly flattened, 2-ribbed, scabrous; pedicels 0.2-1 mm long, scabrous. Spikelets 3-4 mm long, erect, plumbeous to dark olivaceous; glumes 1.2-2 mm long, subequal, scabrid, apex obtuse to truncate, unawned; lower glumes 1.2-1.6 mm long, ovate, usually 1-veined, sometimes unveined; upper glumes 1.6-2 mm long, half as long as the lemma, oblong-obovate, usually 3-veined, but sometimes very faint, 2 or 3-toothed, the teeth 0.3-0.6 mm long, about 1/3 the length of the glume; lemmas 3-4 mm long, lanceolate, pilose below and along margins, the hairs mostly less than 1 mm long, the callus hairy, apex awned, the awns 4-8 mm long, flexuous, scabrous, olive-green, arising from a bifid apex, the teeth up to 0.5 mm long; paleas 3-4 mm long, as long as the lemma, olive-green, scabrous; anthers 1.8-2.1 mm long, fusiform, purple.

Distribution.

The species is endemic to Costa Rica and Panama ( Peterson et al. 2001).

Ecology.

Muhlenbergia flabellata occurs in páramos between 3100-3500 m often associated with Chusquea subtessellata Hitchc., Hypericum , ssp., Comaristaphylos arbutoides Lindl., Garrya laurifolia Hartw. ex Benth., and Buddleja nitida Benth.

Comments.

Muhlenbergia flabellata is a member of M. subg. Clomena and within this clade it is sister to M. quadridentata , a species primarily restricted to higher elevations that is common in México and extends into Guatemala ( Peterson et al. 2021). Muhlenbergia flabellata can be separated from M. quadridentata in having short leaf blades 2-5 cm long (5-15 cm long in M. quadridentata ), short upper glumes 1.6-2 mm long [versus (3-)3.2-4 mm long in M. quadridentata ], and paleas scabrous throughout (versus pilose on the proximal ½ in M. quadridentata ) [ Peterson et al. 2007b; Herrera Arrieta and Peterson 2018].

Specimens examined.

Costa Rica. Cartago: Paraíso, Cerro de la Muerte, Cordillera de Salamanca , near summit of Cerro Sátira, S. Horn 35 (CR); Paraíso, Cerro de la Muerte, M. Kappelle et al. 2377 (CR). Pérez Zeledón: R. F. Los Santos, Cerro Bubis, A. Estrada et al. 2769 (CR); P. N. Chirripó, parte superior (norte) del Valle de los Conejos, J. Gómez 5339 (CR); R.F. Los Santos Alrededores de las torres de TV, cerro Buenavista, L. Gómez 6354 (CR); P. N. Chirripó, alrededores de refugio, parte inferior del valle de los Conejos, J. Gómez-L. 4503 (USJ); P. N. Chirripó, Cordillera de Salamanca , S facing slope of the Valle de los Conejos , about 1 km S of Cerro Nuevo, S. Horn 59 (CR); P.N. Chirripó, Valle de los Conejos, R. Ocampo 1466 (CR); P.N. Chirripó, Valle de los Conejos, R. Ocampo 1489 (CR); Rivas, A. Rodríguez 6422 (INB); Perez Zeledon , Rivas, A. Rodríguez 6541 (INB); P.N. Chirripó, refugio Los Crestones, G. Vargas et al. 340 (USJ); disturbed paramo, Cerro de la Muerte, R. Chazdon 447 (CR); Cordillera de Talamanca , Cerro de la Muerte , summit of Cerro Buvis, R.W. Pohl & G. Davidse 11621 (US); Direct line from Hotel La Georgina to Cerro Frio of the Cerro Buenavista complex ( Cerro de la Muerte ), area with television and radio towers, G. Davidse 24971 ( US, MO); Open paramo formation with stands of Chusquea bamboo 1-2.5 m tall and areas of short-burned forest and original forest 5-15 m tall in protected sites, along the trail to the Valle de los Leones and the lower part of theValle de los Conejos along the upper Rio Talari, W. Burger & L.D. Gomez 8309 (US). San Jose: W.C. Burger & R. Liesner 7467 (MO); Chirripó, G. Davidse & R. W. Pohl 1541 (MO); Buenavista, A. Jiménez 2666 (MO); Parque Nacional Chirripó, Páramo near Albergues de los Crestones, along Rio Talari near trail to Valle de los Conejos, J. G. Pruski et al. 3904 (MO); Buenavista, A. Weston 5846 (MO); Cerro Buenavista, P.M. Peterson, S. Lobo, J. Sánchez & R. Chacón 22855 (CR, US); P. N. Chirripó Open paramo formation with stands of Chuquea bamboo 1-2.5 m tall on slopes and in the valley, short grasses and very short (30 cm)shrubs on the exposed ridges, Valle de los Conejos (upper río) Talari and trails to Cerro Chirripó and the Valle de Los Lagos , W.C. Burger & R. Liesner 7353 (CR); P. N. Chirripó, A. Chaverri et al. 1026 (CR); P. N. Chirripó Valle de los Conejos, A. Chaverri et al. 1172 (CR) , Panama. Bocas del Toro: Fábrega, A. Weston 10190 (MO) .

Figures

Figure 9. A-E Muhlenbergia flabellata Mez. A habit B ligule C glumes D floret E floret F-J Muhlenbergia montana (Nutt.) Hitchc F habit G inflorescence H glumes I upper glume J florets. A, B, D, E drawn from W. C. Burger & L. Gomez P. 8309 (US- 2695054) C drawn from G. Davidse 24971 (US- 3014559) F-J drawn from A. S. Hitchcock 3143 (US- 995116).