Muhlenbergia flexuosa Hitchc., Contr. U.S. Natl. Herb. 24(8): 388. 1927.
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https://dx.doi.org/10.3897/phytokeys.114.28799 |
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https://treatment.plazi.org/id/5512FD5D-9632-0A05-D900-5EDE8A24A463 |
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Muhlenbergia flexuosa Hitchc., Contr. U.S. Natl. Herb. 24(8): 388. 1927. |
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10. Muhlenbergia flexuosa Hitchc., Contr. U.S. Natl. Herb. 24(8): 388. 1927. Fig. 9A-E View Figure 9
Type.
Peru, Huacachi Estacion near Muna, summit of rocky crest, 2000 m, 20 May-1 Jun 1923, J.F. Macbride 3874 (holotype: F-534937!; isotypes: BAA-1622!, BM-000938657 [image!], G-00099373 [image!], K!, LE!, US-1256339!).
Description.
Caespitose perennials. Culms 15-40 cm tall, slender, 0.3-0.4 mm diameter just below the panicle with 6-8 nodes per culm; internodes 1-6 cm long near base, glabrous, shiny. Leaf sheaths about as long as the internodes below, glabrous; ligules 0.3-0.5 mm long, membranous, apex truncate, lacerate; blades 2-5 cm long, 1-2.2 mm wide, flat, scaberulous, apex acuminate. Panicles 3.5-6.5 (-7) cm long, 0.5-1.5 cm wide, narrow, spiciform, sometimes interrupted below; primary branches 0.5-2.5 cm long, tightly apressed to loosely ascending or spreading, not more than 45° from the culm axis. Spikelets 2.8-4.2 mm long, yellowish to light brown, erect or drooping; glumes 2.8-4 mm long, including mucos or awns, subequal, hyaline to membranous, glabrous, 1-veined, scabrous along the midvein, apex acute, unawned, mucronate or awned, the awns up to 1.3 mm long, straight or loosely flexuous; lemmas 2.8-4.2 mm long, hyaline to membranous, 3-veined, scaberulous, lower 1/3 sparsely hairy, apically awned, the awns 14-30 mm long, flexuous, callus hairy, the hairs up to 0.4 mm long; paleas about as long as the lemmas, 2-veined, glabrous, apex acuminate, often mucronate; anthers 1.3-1.6 mm long, purple. Caryopses 1.4-1.6 mm long fusiform, light brown.
Distribution.
Muhlenbergia flexuosa endemic to Peru and is known from only a few collections from Huánuco, Pasco and San Martín departments ( Hitchcock 1927; Tovar 1993).
Ecology.
Steep talus slopes, rocky trail cuts and rock outcropts with Andropogon , Acacia , Chusquea , Baccharis , Puya , Salvia , Rubus , Muhlenbergia ciliata , M. beyrichiana , Acanthaceae and Melastomataceae ; 1200-2530 m.
Comments.
Hitchcock (1927) suggested Muhlenbergia flexuosa was allied with M. flaviseta Scribn. and M. watsoniana Hitchc. (≡ M. scabra S. Watson), since all have short flat blades, spike-like panicles and slender flexuous awns. However, Muhlenbergia flaviseta and M. watsoniana are members of the M. subg. Clomena clade while M. flexuosa is sister to M. plumiseta Columbus- M. pereilema P.M. Peterson- M. beyrichiana clade, all of which are included in M. subg. Muhlenbergi a (Fig. 1 View Figure 1 ; Peterson et al. 2010b). Within Muhlenbergia , the derivation of a slender flexuous awn found in M. flexuosa has occurred in four of the five subgenera currently recognised within the genus and is only lacking in M. subg. Pseudosporobolus (Fig. 1B View Figure 1 ; Peterson et al. 2010b).
Specimens examined.
Peru. Huánuco: Rio Huallaga Cañon, below Rio Santo Domingo, 1316 m, 3 Jun 1923, J.F. Macbride 4205 (US); Pachitea, Canyon of the Rio Grande, 44 air km E of Huánuco, 2 air km ESE of Estación Huacachay (Huacachi), 9°51'34.7"S, 75°50'48.1"W, 1867 m, 7 Mar 2007, P.M. Peterson, R.J. Soreng & K. Romaschenko 20358 (MO, US, USM); 1.5 air km SE of Estación Huacachay (Huacachi), 9°51'42.8"S, 75°50'23.4"W, 2383 m, 8 Mar 2007, P.M. Peterson, R.J. Soreng & K. Romaschenko 20365 (MO, US, USM); along trail 1/3 air km NW of Estación Huacachay (Huacachi), 9°51'1.4"S, 75°49'53.4"W, 2519 m, 8 Mar 2007, P.M. Peterson, R.J. Soreng & K. Romaschenko 20373 (US, USM). Junin: Cerro Taldes, Rio Huancabamba, 31 km S of Pozuzo and 3 km N of Llullitunqui, 1370 m, 1 Jun 1979, H. Teppner 79-293 (US). Pasco: Oxapampa, Pozuzo, 21 Jul 1978, Ellemberg 8934 (USM). San Martín: Mariscal Caceres, 2350 m, 13 Aug 1986, K. Young 4234 (MO).
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