Muhlenbergia capillaris (Lam.) Trin., Gram. Unifl. Sesquifl. 191-192, 296, t. 5, f. 15. 1824.

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

3. Muhlenbergia capillaris (Lam.) Trin., Gram. Unifl. Sesquifl. 191-192, 296, t. 5, f. 15. 1824.

Fig. 4A-D

Stipa capillaris Lam., Tabl. Encycl. 1: 158. 1791. Type: USA, E. Carolina, D. Fraser s.n. (holotype: P-LAM!; isotypes: MPU-026956 [image!], US-A866136 fragm. ex P-LAM!). ≡ Podosaemum capillare (Lam.) Desv., Nouv. Bull. Sci. Soc. Philom. Paris, sér 2 2: 188. 1810. ≡ Trichochloa capillaris (Lam.) DC., Cat. Pl. Horti Monsp. 152. 1813. Basionym.

Description.

Caespitose perennials. Culms 60-100(-150) cm tall, erect from the base, not conspicuously branched; internodes mostly glabrous, sometimes puberulent below the nodes. Leaf sheaths glabrous or puberulent, basal sheaths terete, often becoming fibrous, but never spirally coiled, at maturity; ligules 1.8-5(-10) mm long, membranous, firm, strongly decurrent, obtuse; blades 10-35(-80) cm long, 2-4 mm wide, flat or involute, smooth abaxially, scabrous adaxially. Panicles 15-50(-60) cm long, 8-30(-41) cm wide, longer than wide, diffuse; primary branches 2-20 cm long, capillary, diverging 30-100° from the culm axis, naked basally, lower branches with 5-20 spikelets; pedicels 10-40(-50) mm long, longer than the spikelets, capillary, flexible. Spikelets 3-5 mm long, usually purple, occasionally green, brown, or stramineous; glumes (0.3-)1-1.5(-2) mm long, usually less than 1/2 as long as the lemmas, subequal, glabrous; lower glumes 1-veined, usually unawned, rarely awned, awns 1-3 mm long; upper glumes 1-veined, rarely 3-veined, acute to acuminate, often erose, usually unawned, rarely awned, awns 1-3(-5) mm long; lemmas 3-5 mm long, lanceolate, not shiny, calluses short pubescent, apices scabrous, acuminate, sometimes with 2 setaceous teeth, teeth to 1 mm long, unawned or awned, awns 2-13(-18) mm long, clearly demarcated from the lemma bodies; paleas 2-4.5 mm long, lanceolate, acuminate, usually unawned; anthers 1.5-2 mm long, purple. Caryopses 2-2.5 mm long, narrowly elliptic, brownish.

Distribution.

Muhlenbergia capillaris ranges from the southeastern United States, the Caribbean coast of México (Quintana Roo), extending to Guatemala, Bahamas, and various Caribbean islands ( Peterson et al. 2001). It is also grown as an ornamental. This species was reported from the Yucatán ( Dávila et al. 2018) but we have been unable to locate a specimen to verify this record.

Ecology.

Muhlenbergia capillaris occurs in open woodlands, pine-oak forests, savannahs and on rock outcrops; 0-2020 m.

Comments.

Muhlenbergia capillaris can be separated morphologically from M. rigida in having panicles 8-30(-41) cm wide with open, diffuse branches that are strongly divergent, whereas M. rigida has loosely contracted panicles 2-5(-12) cm wide with appressed to ascending branches spreading up to 80° from the culm axis. Muhlenbergia capillaris , a member of M. subg. Trichochloa , is found in a strongly supported clade sister to M. expansa (Poir.) Trin., a species from the southeastern USA (Fig. 1 ; Peterson et al. 2021).

Specimens examined.

Guatemala. Guatemala : Guatemala City, open prairie, A.S. Hitchcock 9141 (US-995855) ; Huehuetenango: Rocky dry slopes above San Ildefonso, Ixtahuacan, J.A. Steyernmark 50673 (US-1935074, US-2208677) ; Quiché: Chichicastenango, 1 km north of Chichicastenango. Small “prairie” next to a milpa, shallow soil on sandstone, W.E. Harmon 4364 (MO), mts. E of Quiche, V. Grant 645 (US-1818233). Mexico. Chiapas: near ranch house on S edge of Teopisca, D.E. Breedlove & P.H. Raven 13097 (MICH); Marsh near Teopisca, D.E. Breedlove & G. Davidse 54803 (MICH, CAS, MO); Teopisca, slope at W edge of Teopisca, D.E. Breedlove & J.L. Strother 46373 (CAS, MO). Quintana Roo: José María Morelos: Lake Chichancanab (Laguna Chan-kabnab), 28-29 July 1932, J.R. Swallen 2726 (MO, US-1537112, US-3090503) .

Figures

Figure 1. A, B Bayesian tree inferred from combined plastid (ndhA intron, rps 16 - trnK, rps 16 intron, rps 3, and rpl 32 - trnL) and ITS sequences. Thick branches indicate posterior probabilities of 0.95 - 1; species in bold occur in Central America; Scale bar: 2 %.

Figure 4. A-C Muhlenbergia capillaris (Lam.) Trin. A habit B glumes C floret. A-C drawn from F. Lamson Scribner s. n. (US- 746068) used in Hitchcock (1935).