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) .