Muhlenbergia maxima Laegaard & Sanchez Vega, Nordic J. Bot. 10: 439. 1990.

Peterson, Paul M., Vega, Isidoro Sanchez, Romaschenko, Konstantin, Giraldo-Canas, Diego & Rodriguez, Nancy F. Refulio, 2018, Revision of Muhlenbergia (Poaceae, Chloridoideae, Cynodonteae, Muhlenbergiinae) in Peru: classification, phylogeny, and a new species, M. romaschenkoi, PhytoKeys 114, pp. 123-206 : 158-160

12. Muhlenbergia maxima Laegaard & Sanchez Vega, Nordic J. Bot. 10: 439. 1990. Fig. 2F-H

Type.

Peru, Prov. Cajamarca, Choten between Paso El Gavilán and San Juan at km 153 on the road to the coast, 2900 m, 29 May 1984, I. Sánchez Vega & Ruiz Vigo 3561 (holotype: CPUN!; isotypes: AAU!, K!, US!, USM!).

Description.

Loosely caespitose perennials. Culms 100-140 cm tall, erect, rigid, terete, ca. 2-3.2 mm diameter near base with 3 or 4 glabrous to pubescent nodes; in ternodes terete above. Leaf sheaths longer than the internodes, mostly basally inserted, compressed-keeled near base, becoming fibrous with age, scaberulous, finely striate; ligules 3-5 mm long, apex irregularly toothed to lacinate, margins entire and extended above to form auricles; blades 25-45 cm long, 2.8-4 mm wide, flat to folded, striate, scabrous, apex attenuate, midvein prominent. Panicles 30-46 cm long, 3-6 cm wide, narrow; branches 6-11 cm long, scabrous, ascending, appressed to loosely spreading, mostly floriferous to base, except on lowest branches; pedicels mostly shorter than the spikelets. Spikelets 2.5-2.8 mm long, 1-flowered, greenish with reddish-purple tinting; glumes 2.2-2.6 mm long, almost equal or shorter than the floret, hyaline to membranous, faintly 1-veined, subequal, the lower usually slightly shorter, glabrous to scattered pubescent, scaberulous; lemmas 2.5-2.8 mm long, ovate, 3-veined, awned, with scattered sericeous hairs more numerous along the veins, scaberulous, the callus pilose, the flexuous awn inserted just below the obtuse to acute apex, the awn 4-9 mm long; paleas about as long as the lemma, faintly 2-veined, sericeous between the veins below; lodicules about 0.1 mm long, truncate, glabrous; stamens 3; anthers 1.3-1.8 mm long, purple. Caryopses 1.4-1.7 mm long, fusiform, brownish.

Distribution.

A Peruvian endemic known only from Amazonas and Cajamarca departments.

Ecology.

Rocky slopes near rivers and grassy slopes in disturbed ground along roads associated with Acacia , Begonia , Cortaderia bifida , C. jubata , Desmodium , Dodonaea viscosa Jacq., Hyptis , Lepechinia , Oxalis , Puya , Salvia and Schizachyrium ; 2100-2900 m.

Comments.

Muhlenbergia maxima is a member of M. subg. Trichochloa ( Peterson et al. 2010b). Muhlenbergia inaequalis Soderstr. endemic to Colombia and Venezuela and M. lehmanniana Henr. ranging from Costa Rica to Colombia ( Lægaard and Sánchez Vega 1990; Giraldo-Cañas and Peterson 2009) are morphologically similar to M. maxima . Muhlenbergia maxima differs from M. inaequalis and M. lehmanniana in having shorter lemmatal awns and a longer ligule than M. inaequalis (0.5-1.5 mm long) and a shorter ligule than M. lehmanniana (1-2.5 cm long). There is not much genetic variation among all members of M. subg. Trichochloa in Peterson et al. (2010a) and a detailed population genetic study of these three South American species is needed to interpret their evolutionary history.

Specimens examined.

Peru. Amazonas: 27 km from Balsas towards Leymabamba, 2250 m, 23 Mar 1988, S.A. Renvoize & S. Lægaard 4908 (CPUN, K); 66 km from Leymebamba towards Balsas, 2100 m, 25 Mar 1988, S.A. Renvoize & S. Lægaard 4935 (CPUN, K, MO, US). Cajamarca: Prov. Cajabamba, 14 air km WSW of Cajabamba and 2.5 km on road W of Araqueda, 7°39'9.1"S, 78°9'58.9"W, 2242 m, 23 Mar 2008, P.M. Peterson & R.J. Soreng 21853 (MO, US, USM); Prov. Cajamarca, S of Paso El Gavelán, ca. 10 air km S of Cajamarca, just above km post 150 on hwy 8 above San Juan, 7°15'37.2"S, 78°30'34.5"W, 2544 m, 26 Mar 2008, P.M. Peterson, R.J. Soreng & I Sánchez Vega 21884 (US, USM); Dist. San Juan, entre San Juan y Paso el Gavilán, 2650 m, 30 May 2003, I. Sánchez Vega 11965, M. Sánchez M. y R. Cueva R. (CPUN, HAO); Celendin, Marañón River Valley, Chachapoyas-Cajamarca road, 2100 m, 28 May 1984, D.N. Smith & J.M. Cabanillas S. 7271 (MO, US).

Figures

Figure 2. A-E Muhlenbergia beyrichiana Kunth A habit B ligule with auricles C glumes D floret E stamens and pistil F-H Muhlenbergia maxima Laegaard & Sanchez Vega F habit G end of panicle branch H floret. A-E drawn from A. S. Hitchcock 20635 (US) F-H drawings from Laegaard & Sanchez Vega (1990) drawn from the holotype collection Sanchez Vega & Ruiz Vigo 3561.