Muhlenbergia peruviana (P. Beauv.) Steud., Nomencl. Bot. (ed. 2) 1:41. 1840.

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

22. Muhlenbergia peruviana (P. Beauv.) Steud., Nomencl. Bot. (ed. 2) 1:41. 1840.

Fig. 12A-D

Clomena peruviana P. Beauv., Ess. Agrostogr. 28, t. 7, f. 10; t. 3, f. 20. 1812. Agrostis peruviana (P. Beauv.) Spreng., Syst. Veg. 1:262. 1825. Type: Peru, M. Thibaut s.n. (holotype: P!; isotype: E-00373717 [image!]). Basionym.

= Clomena peruviana var. pulvinata Nees, Gramineae 12-13. 1841. Muhlenbergia peruviana var. pulvinata (Nees) Nees & E. Mey. ex Kuntze, Revis. Gen. Pl. 3(3):357. 1898. Type: Peru, Lago Titicaca, Apr, J.F.J. Meyen s.n. (holotype: B; isotype: US-3376134 fragm. ex B!).

= Muhlenbergia nana Benth., Pl. Hartw. 262. 1846. Type: Ecuador, Mt. Cotopaxi, 1843, Hartweg 1458 (holotype: K!; isotypes: BAA-1629!, K!, LE!, P!, US-91916 fragm. ex P!, US-995896 fragm. ex P-STEUD & fragm. ex BR!).

= Muhlenbergia pusilla Steud., Syn. Pl. Glumac. 1:177. 1854. Type: México, México, Valley of Toluca, Oct. 1827, J. L. Berlandier 1141 (holotype: P!; isotypes: BAA-1635!, K!, MO-2974185!, P!, US-1084517!, US-2561239!, US-91910 fragm. ex P!).

= Epicampes bourgeaei E. Fourn., Mexic. Pl. 2: 88. 1886. Type: México, Veracruz, Escamala, Refrou D’Orizaba, 26 Aug 1866, E. Bourgeau 2973 (holotype: P!; isotype: US-A0865984 fragm ex P!).

= Muhlenbergia bourgeaei E. Fourn., Mexic. Pl. 2:86. 1886. Type: México, Valle de México, Desierto Viejo, 3 Nov 1865, M. Bourgeau 1309 (lectotype: P! designated by Peterson and Annable, Syst. Bot. Monogr. 31:73. 1991; isotype: US-87243 fragm. ex P!). ≡ Epicampes bourgeaei (E. Fourn.) M.E. Jones, Contr. W. Bot. 14:7. 1912, nom. illeg. hom.

= Muhlenbergia pulcherrima Scribn. ex Beal, Grass. N. Amer. 2:240. 1896. Type: México, Chihuahua: Sierra Madres, dry ledges of porphyry, 30 Sep 1887, C.G. Pringle 1416 (holotype: MSC!; isotypes MO-3727978!, NY!, US-995494!, VT!).

= Muhlenbergia peruviana var. elatior Kuntze, Revis. Gen. Pl. 3(2): 357. 1898. Type: Bolivia, Tunarigebirge, 3000 m, May 1892, Kuntze s.n. (lectotype: NY! designated by Peterson and Annable, Syst. Bot. Monogr. 31:73. 1991: isotype: fragm. & photo US!).

= Muhlenbergia peruviana var. subcaespitosa Kuntze, Revis. Gen. Pl. 3(3):357. 1898. Type: Bolivia, Tunari Mts., 4600 m, 4 May 1892, Kuntze s.n. (lectotype: NY! designated by Peterson and Annable, Syst. Bot. Monogr. 31:73. 1991).

= Muhlenbergia peruviana fo. versicolor Kuntze, Revis. Gen. Pl. 3(3):357. 1898. Type: Bolivia, Tunarigebirge, 3000 m, May 1892, Kuntze s.n. (lectotype: NY! designated by Peterson and Annable, Syst. Bot. Monogr. 31:73. 1991; isotype: US fragm. ex NY!).

= Muhlenbergia peruviana fo. viridis Kuntze, Revis. Gen. Pl. 3(3):357. 1898. Type: Bolivia, Puna, 4000 m, 11 Mar 1892, Kuntze s.n. (lectotype: NY! designated by Peterson and Annable, Syst. Bot. Monogr. 31:73. 1991).

= Muhlenbergia herzogiana Henrard, Meded. Rijks-Herb. 40:58. 1921. Type: Bolivia, Cordillera de Santa Bonita, Jun 1911, T. Herzog 2226 (holotype: L!; isotypes: US-87248 fragm. ex L!, US-1161342!, W-1926-23724!).

Description.

Tufted annuals. Culms 3-27 cm tall, erect, glabrous. Leaf sheaths usually longer than the internodes, smooth or scabridulous; ligules 1.5-3 mm long, membranous, acute; blades 1-5 cm long, 0.6-1.5 mm wide, flat to involute, smooth or scabridulous abaxially, sometimes shortly pubescent adaxially. Panicles 2-8 cm long, 0.3-3.4 cm wide, contracted or open; primary branches 1-5 cm long, diverging up to 80° from the rachises; pedicels 0.4-5 mm long, smooth or scabrous. Spikelets 1.4-4.2 mm long, 1-flowered; glumes smooth or scabridulous; lower glumes 0.8-2.8 mm long, narrow to broadly lanceolate, 1-veined, acute, often awn-tipped; upper glumes 0.9-3 mm long, wider than the lower glumes, lanceolate, 3(2)-veined, truncate to acute, 2- or 3-toothed; lemmas 1.4-4.2 mm long, ovate, widest near the base, purplish mottled with dark green areas, hairy on the calluses and lower 2/3 of the lemma bodies, hairs to 0.5 mm long, apices acuminate, usually bifid and awned from between the teeth, teeth to 0.5 mm long, awns 3-10 mm long, flexuous, purplish; paleas 1.3-3.8 mm, narrowly lanceolate, acuminate to subacute; anthers 0.5-1 mm long, purplish to yellowish. Caryopses 1-1.6 mm long, fusiform, brownish. 2 n = 30.

Distribution.

Muhlenbergia peruviana occurs in Arizona and New Mexico, U.S.A, throughout México to Guatemala, and then in Argentina, Bolivia, Chile, Ecuador, and Peru ( Peterson and Annable 1991).

Ecology.

Grassy flats, open gravelly flats, rock outcrops, sandy washes, gravelly drainages, wet or dry meadows, canyons, gravelly or sandy slopes, valleys, shores along lakes, open ridgetops, and disturbed road cuts associated with Aciachne pulvinata Benth., Anatherostipa , Berberis , Colletia spinosissima , Ephedra , Festuca orthophylla Pilg., Festuca ssp., Jarava , Juncus , Lepidophyllum , Luzula , Margyricarpus , Monnina , Muhlenbergia ssp., Nassella , Plantago , Poa ssp., Polylepis , Puya , Pycnophyllum , Salvia oppositiflora Ruiz & Pav., Stevia , Tagetes ; 3000-4900 m.

Comments.

As treated here, Muhlenbergia peruviana includes (as synonyms) what was sometimes identified as M. pulcherrima Scribn. ex Beal (southwestern USA and northern México) and M. pusilla Steud. (central México to Guatemala). There are many more morphological forms than just these, and since the only chromosome count of this species suggests triploidy (2 n = 3 x =30), perhaps this species is apomictic ( Reeder 1968). We believe apomixis is occurring in this species but that it is not obligate, and that gene flow takes place sporadically to form intermediates maintained by asexual seed formation ( Peterson and Annable 1991).

In a molecular DNA sequence analysis Muhlenbergia peruviana is sister to M. crispiseta Hitchc., another annual known only from Texas and north central México, and this pair is embedded in the strongly supported M. subg. Clomena clade ( Peterson et al. 2010b, Peterson et al. 2021). Members of M. subg. Clomena possess spikelets with upper glumes that are 3-veined and often 3-toothed and have a densely caespitose habit ( Peterson et al. 2010b). Muhlenbergia peruviana can be separated from M. crispiseta in having purplish irregularly flexuous, purplish awns (versus sinuous-wavy, crisped and curled, olive-green awns in M. crispiseta ) and narrow, gradually acuminate lemmas (versus lemmas that are plump near middle) [ Peterson and Annable 1991].

Specimens examined.

Guatemala. Huehuetenango: La Capellania , Sierra de los Cuchumatanes , 1.0 miles NW of La Capellania on hwy 9N and 12.3 miles N of Huehuetenango, P.M. Peterson & C.R. Annable 4683 (GH, MEXU, MICH, MO, NY, RSA, UC, US, WS); Tojiah , Sierra de los Cuchumatanes, 3 miles SW of Tojiah on hwy 9 N., P.M. Peterson & C.R. Annable 4698 (GH, MO, NY, RSA, US, WS); Treeless paramo-like plain near Calaveras, L.O. Williams et al. 21961 ( US) . San Marcos : Tacana, Volcán Tacaná, M. Véliz et al. 10587 (MO) . Mexico. Chiapas: NW de Motozintla de Mendoza on road to El Porvenir, P.M. Peterson & C.R. Annable 4712 (US) ; 13 mi NW de Motozintla de Mendoza off road to El Porvenir at top of cumbre below tower, P.M. Peterson & C.R. Annable 4714 ( US) .

Figures

Figure 12. A-D Muhlenbergia peruviana (P. Beauv.) Steud. A habit B floret C glumes D ligule E-H Muhlenbergia minutissima (Steud.) Swallen E habit F ligule G spikelet H floret. A-D drawn from P. M. Peterson & C. R. Annable 4067 (US, WS) E, G, H drawn from P. M. Peterson & C. R. Annable 5601 (US- 3182908) F drawn from P. M. Peterson & C. R. Annable 4675 (US, WS).