Agrostis breviculmis Hitchc., U.S.D.A. Bur. Pl. Industr. Bull. 68: 36, pl. 18. 1905

Sylvester, Steven P., Cuta-Alarcon, Lia E., Bravo-Pedraza, William J. & Soreng, Robert J., 2020, Agrostis and Podagrostis (Agrostidinae, Poaceae) from paramos of Boyaca, Colombia: synoptic taxonomy including a key to Colombian species, PhytoKeys 151, pp. 107-160 : 107

Agrostis breviculmis Hitchc., U.S.D.A. Bur. Pl. Industr. Bull. 68: 36, pl. 18. 1905 Fig. 3

Trichodium nanum J. Presl, Reliq. Haenk. 1 (4-5): 243. 1830.

Agrostis nana (J. Presl) Kunth, Enum. Pl. [Kunth] 1 (1): 226. 1833.

Type.

Peru. Hab. in Peruvia, T. Haenke s.n. [#192 in W0014114 isotype] (holotype: PR; isotypes: BR (BR0000006864774 [image!]), MO (MO2104691 [image!]; MO2104692 [illustration]; MO2114552 [image!]), LE-TRIN (LE-TRIN1627.01 fragm. & fig.), W (W0014113 [image!]; W0014114 [image!])).

Description.

Perennial herbs, densely tufted, not stooling and without notable lateral tending or ascending rhizomes. Tillers intravaginal, without cataphylls. Culms 3-12(-15) cm tall, erect to arched, firm, usually with 0 nodes exerted at flowering. Leaves basal, glabrous, smooth or scaberulous; ligules c. 1 mm long, membranous or slightly scarious, triangular and obtuse, moderately to strongly decurrent with the sheath, abaxial surface smooth or scaberulous; blades 1-4(-6) cm long, 0.25-1 mm wide in diameter as folded or rolled, usually convolute, less often strongly conduplicate, recurved, rigid, abaxial surface usually smooth throughout, rarely scaberulous towards the apex, adaxial surface and margins generally scaberulous, sometimes moderately scabrous, apices blunt to slightly broadly naviculate-acute. Panicles 1-2.6(-3) cm long, c. 0.05-0.2(-0.6) cm wide, densely congested, spikelike, generally uninterrupted, subincluded in the basal foliage to slightly or moderately exerted, lateral branches with spikelets almost to the base, upper lateral branches short and held close to the central inflorescence axis, central axis and panicle branches scabrous or smooth; pedicels 0.9-2 mm long, usually shorter than their spikelets, not obviously dilated at their apex, smooth or scaberulous. Spikelets 1.5-2.1 mm long (-2.5 mm long in Bolivia?; Renvoize 1998); glumes equal or subequal, lower glume sometimes longer than upper by up to 0.2 mm and slightly to notably wider, 1-veined, lower glume keel scabrous at least in the distal half, prickle hairs coarse and shiny, upper glume keel like that of lower glume or with fewer scabers to sometimes smooth throughout, apices acute; floret 2/3-3/4 the length of the glumes; calluses pilose, usually with 2 lateral tufts of short hairs; lemmas 1.2-1.4 mm long, glabrous, smooth, 5-veined, apex truncate, erose and 4-mucronate, muticous or with a short straight awn to 0.9 mm long, inserted above the middle, not or only briefly surpassing the glume apex, weak and falling easily; paleas absent or to 0.3 mm long, < ¼ the length of the lemma; rachilla absent; anthers 0.5-0.9 mm long.

Distribution and ecology.

Amply distributed in the high Andes, from Colombia and Venezuela to Chile and Argentina. Predominantly found in open, grazed páramo and puna vegetation, 3200-4500 m alt.

Other specimens examined.

Colombia. Boyacá: Munic. Chiscas, Vereda Rechiniga, Páramo de la Mesa, páramo perturbado, dominado por Espeletia y gramíneas exóticas, con presencia de ganadera caprina, 6.59291N, 72.44541W, 3694 m alt., 3 Mar. 2018, S.P. Sylvester 3096 (FMB, US); Munic. Duitama, Páramo de la Rusia, vía que conduce a vereda de Avendanos, 5.9324667N, 73.0798W, 3726 m alt., 4 Oct. 2017, S.P. Sylvester 3024 (FMB, K, UPTC, US); Munic. Duitama, Páramo La Rusia, Guanenta Alto Río Fonce National Park, top of the ridge Peña Negra just below military base, ridge along the top of a steep rocky landscape, open páramo with Espeletia cachaluensis [ Rodríguez-Cabeza], edges of the road, 5.58389N, 73.053263W, 3970 m alt., 21 Nov. 2017, M. Vorontsova 2217 (FMB, K, US); Munic. Mongua, Páramo de Ocetá, Valle de Laguna Negra, pajonal frailejonal, terreno inclinado en medio de valle, 5.7066389N, 72.8036111W, 3699 m alt., 29 Nov. 2017; L.E. Cuta-Alarcón 364 (FMB, K, US).

Similar species.

Agrostis boyacensis and A. meyenii also have congested spikelike panicles and florets with a small palea and which lack awns. See notes under A. boyacensis for how to differentiate these taxa. Agrostis meyenii can be principally differentiated by its larger spikelets, 2.2-4.1 mm long, and softer, lax, filiform to flat or folded leaf blades. Agrostis laegaardii A.M. Molina & Rúgolo, a recently described species found in Ecuador and the Páramo del Ruiz of the Cordillera Central of Colombia ( Palacio et al. in press), also bears very close resemblance. These similarities include: a) plants 3-12 cm tall; b) tillers intravaginal, without notable lateral tending or ascending rhizomes; c) leaf blades convolute, recurved, rigid, 0.5-2 mm wide when opened out, apices blunt or slightly naviculate-acute; d) ligules c. 1 mm long; and e) glumes with coarse shiny prickle hairs along the keel. Agrostis breviculmis can be differentiated from A. laegaardii by a) often larger spikelets, (1.7-)2-3.3 mm long (vs. 1.5-2.1(-2.5) mm long in A. breviculmis ); b) pedicels slightly widened towards the apex and cupuliform (vs. pedicel apex not dilated, truncate, in A. breviculmis ); c) glumes membranous, standard V-shaped in cross section (vs. chartaceous, narrow V-shaped in cross section in A. breviculmis ); d) lower glume narrowly ellipsoid (vs. navicular in A. breviculmis ); e) upper glume scabrous in upper 2/3-3/4 (vs. scabrous in upper ½ in A. breviculmis ); f) distance between upper glume and floret (0.5-)0.7-1 mm (vs. 0.3-0.5 mm in A. breviculmis ); g) lemma (1.6-)1.7-2 mm long, lateral veins terminating in 4 aristulas (vs. 1.2-1.4 mm long, lateral veins terminating in 4 mucrons in A. breviculmis ); h) lemmas with well-developed geniculate awns (1.6-)2.3-3 mm long, inserted in the middle or upper third of the lemma, exerted from the glumes, persistant (vs. awnless or with a short straight awn to 0.9 mm long, inserted above the middle, not or only briefly surpassing the lemma apex, weak and falling easily, in A. breviculmis ); and i) palea 0.4-0.5 mm long (vs. 0.2-0.3 mm long in A. breviculmis ).

Figures

Figure 3. Agrostis breviculmis A spikelet, glumes in lateral view, floret in ventral view, detached and raised above the glumes B whole plant. Images of Cuta-Alarcon 364 (FMB).