Muhlenbergia ramulosa (Kunth) Swallen, Contr. U.S. Natl. Herb. 29(4): 205. 1947.

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

27. Muhlenbergia ramulosa (Kunth) Swallen, Contr. U.S. Natl. Herb. 29(4): 205. 1947.

Fig. 19A-D

Vilfa ramulosa Kunth, Nov. Gen. & Sp. 1: 137. 1815. Type: México, Jorulla, F.W.H.A. Humboldt & A.J.A. Bonpland s.n. (lectotype: P-HBK! designated in Peterson and Annable, Syst. Bot. Monographs 31: 77. 1991; isolectotypes: B-WILLD!, US! fragm ex P). ≡ Sporobolus ramulosus (Kunth) Kunth, Rev. Gram. 1: 68. 1829. Basionym.

= Sporobolus wolfii Vasey, Bull. Torrey Bot. Club 10: 52. 1883. Type: U.S.A., Colorado, Twin Lakes, 1873, J. Wolf 1077 (holotype: US!; isotypes: MO!, NY!, US!). ≡ Muhlenbergia wolfii (Vasey) Rydberg, Bull. Torrey Bot. Club 32: 600. 1905.

Description.

Annuals; delicate, slender, often purplish. Culms (3-)5-25 cm tall, erect or spreading, geniculate, branched at the base, glabrous to minutely scaberulous below the nodes, branching below, striate, 0.2-0.3 mm in diameter just below the inflorescence; internodes 3-40 mm long. Leaf sheaths 3-30 mm long, usually shorter than the internodes, glabrous to minutely scaberulous, margins hyaline, scaberulous; ligules 0.2-0.5 mm long, hyaline, apex truncate, ciliate, without lateral lobes (auricles), margins entire; blades 5-30 cm long, 0.8-1.2 mm wide, involute or flat, minutely puberulent above, glabrous below. Panicles (1-)2-9 cm long, 0.6-2.7 cm wide, ovoid or deltoid, sparsely flowered; primary branches (0.5-)1-3.2 cm long, ascending to spreading (open) or closely appressed; pedicels 1-3 mm long, glabrous or scabrous, rigid. Spikelets 0.8-1.3 mm long, erect; glumes 0.4-0.7 mm long, equal, 1-veined, glabrous, whitish, obtuse or subacute, awnless; lemmas 0.8-1.3 mm long, oval, plump, with mottled with dark greenish-black areas and greenish-white or ochroleucous areas, inflated at maturity, glabrous or appressed-pubescent on margins and midvein, apex acute, awnless; paleas 0.7-1.3 mm long, oval; anthers 0.2-0.3 mm long, purplish. Caryopses 0.5-1 mm long, ellipsoid, brownish to purplish. n = 10.

Distribution.

Muhlenbergia ramulosa ranges from the southwestern United States, México, Central America (Guatemala and Costa Rica), and Argentina ( Peterson and Annable 1991).

Ecology.

It occurs in open pine-oak and tropical forests; 1620-3400 m.

Comments.

Muhlenbergia ramulosa does not align within the five existing subgenera but is instead sister to the common ancestor shared between the well supported clades of all species in M. subg. Bealia and in M. subg. Trichochloa ( Peterson et al. 2021). We place M. ramulosa in a separate subgenus, M. subg. Ramulosae P.M. Peterson below.

Specimens examined.

Costa Rica. Cartago: Oreamuno, Volcán Iraza, devastated area at end of Park Road above Sanitario Duran, growing on ash R.W. Pohl 14209 (MO); Cordillera Central, lower slopes of Volcan Irazu, 1 km below San Juan de Chicoa, R.W. Pohl & G. Davidse 11417 ( US, CR); Cráter del Volcan Irazú, O. Jimenez 1151 ( US, CR). Guatemala. Chimaltenango: Chichavac, A.F. Skutch 665 ( US). Huehuetenango: Santa Eulalia, Sierra de los Cuchumatanes, 13 mi NW of Santa Eulalia on road to San Mateo Ixtatán, moist meadow, associates: Sibbaldia and Deschampsia , P.M. Peterson & C.R. Annable 4693 (GH, MO, NY, US, WS); meadow at Tojiah on Hwy 9N, P.M. Peterson & C.R. Annable 4696 (NY, US. WS); 3mi SW of Tojiah on Hwy 9N, P.M. Peterson & C.R. Annable 4699 (NY, US, WS); Todos Santos Cuchumatan, cerca de la Torre, J.R. Gálvez et al. 96.5812 (MO); between Tojiah and Chemal at km 319.5 on Ruta Nacional 9N, J.H. Beaman 3876 ( US). Quetzaltenango: Cerro Calel, M. de Koninck 153 ( US). Sacatepequez: Volcán de Acatenango, M. Véliz et al. 10292 (MEXU, MO); Volcano de Agua, A.S. Hitchcock 9125 ( US). Mexico. Chiapas: NW de Motzintla de Mendoza on road to El Porvenir, P.M. Peterson & C.R. Annable 4711 ( US, MO); 13 mi NW of Motozintla de Mendoza off road to El Porvenir, P.M. Peterson & C.R. Annable 4715 (GH, MICH, MO, NY, RSA, UC, US, WS). Sierra Madre, C.G. Pringle 1425 (MEXU).

Figures

Figure 19. A-D Muhlenbergia ramulosa (Kunth) Swallen A habit B floret C glumes D ligule E-H Muhlenbergia tenuissima (J. Presl) Kunth E habit F floret G glumes H ligule. A drawn from P. M. Peterson & C. R. Annable 5602 (US- 3182911) B-D drawn from P. M. Peterson & C. R. Annable 4661 (US, WS) E-H drawn from P. M. Peterson & C. R. Annable 4751 (US, WS).