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).