Agrostis mertensii Trin., Linnaea 10 (3): 302. 1836

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 mertensii Trin., Linnaea 10 (3): 302. 1836 Fig. 7

Agrostis laxiflora var. mertensii (Trin.) Griseb., Fl. Ross. 4 (13): 442. 1852.

Agrostis canina var. mertensii (Trin.) Kuntze, Revis. Gen. Pl. 3[3]: 338. 1898.

= Agrostis boliviana Mez, Repert. Spec. Nov. Regni Veg. 18 (1-3): 1. 1922. Type: Bolivia. Pinos bei Tarija, 3000 m alt., 22 Jan. 1904, K.A.G. Fiebrig 2821 (lectotype, designated by Rúgolo de Agrasar (2012: 115): BAA (BAA00000014 [image!]); isolectotypes: BAA (BAA00000211 [image!] fragm. ex K), G (G00099216 [image!]), K (K000308377 [image!]), L (L0819974 [image!]; L0819973 [image!]); syntypes: Bolivia. Calderillo, 3000 m alt., Mar. 1904, K.A.G. Fiebrig 2905, BAA (BAA00000013 [image!]; BAA00000210 [image!]), E (E00373832 [image!]), G (G00099217 [image!]), GH (GH00221373 [image!]; GH00221374 [image!]), K (K000308376 [image!]), S (S05-10054 [image!])).

= Agrostis gelida Trin., Mém. Acad. Imp. Sci. Saint-Pétersbourg, Sér. 6, Sci. Math., Seconde Pt. Sci. Nat. 6 (2, Bot.): 343. 1841. Type: Peru. Andibus de Pasco, [ad nives aeternas], E.F. Poeppig s.n. (holotype: LE-TRIN (LE-TRIN1613.01); isotype: US (US75321 fragm.)). Many other heterotypic synonyms.

Type.

USA. Alaska, 1829, D. Mertens s.n. (lectotype, designated by Widen (1971: 52): LE-TRIN (LE-TRIN1622.01, plant 1); isolectotypes: BAA (BAA00001355 [image!] fragm. ex LE-TRIN), S (S-G-263 [image!] fragm. ex LE-TRIN)).

Description.

Perennial herbs, tufted, sometimes with short lateral tending rhizomes present or stooling with pseudostolons present. Tillers extravaginal, with cataphylls present. Culms 20-65 cm tall, erect, ascendant, or geniculate at the base, delicate and slender, with 0-2(-3) nodes exerted at flowering, smooth. Leaves mostly cauline but with basal leaves present, glabrous, smooth throughout or finely scaberulous on the blade adaxial surface and margins; ligules (0.6-)2-6 mm long, membranous or scarious, obtuse to acuminate, not or slightly to moderately decurrent with the sheath, abaxial surface smooth or scaberulous; blades 10-13 cm long, 1-3 mm wide when opened out, usually flat, soft and lax, less often involute and semi-rigid, tiller blades tending to be more involute and thin, semi-rigid, smooth throughout or finely scaberulous on the adaxial surface and/or margins, apices acute to acuminate. Panicles 5-15 cm long, c. 4-16 cm wide, open when flowering and mature, congested when immature, lax, ovoid to pyramidal, slightly to usually greatly exerted from the basal foliage, lateral branches without spikelets in the lower ½, long, ascending, spreading, to somewhat divergent and not held close to the central inflorescence axis at flowering or maturity, adpressed when young, central axis and panicle branches scabrous or smooth; pedicels 1-6(-15) mm long, sometimes shorter to usually much longer than their spikelets, not or slightly dilated at their apex, smooth or scaberulous. Spikelets (not including awn) (2.2-)2.5-3(-4) mm long; glumes unequal, the lower slightly longer than the upper by up to c. 0.5 mm, 1-veined, keels smooth to scabrous throughout or more commonly scabrous in the upper half, apices acute; floret usually 2/3-3/4 the length of the glumes; calluses lightly pilose with 2 sparse lateral tufts of short hairs; lemmas 1.7-2 mm long, glabrous, smooth, 5-veined, apex obtuse to acute, 2-dentate, 2-4 mucronate, awned, awn (1.8-)2.5-4.5 mm long, inserted dorsally in the middle or lower third, exerted from the glumes, flexuose to geniculate, twisted, persistant; paleas absent or 0.2-0.5 mm long, < ¼ the length of the lemma; rachilla absent; anthers 0.5-1 mm long.

Distribution and ecology.

Exhibits a disjunct distribution, being found in very cold Arctic and sub-Arctic areas of the Northern Hemisphere (i.e. North America, Europe and Asia), and also in the high Andes of Venezuela, Colombia, Peru, Bolivia, Argentina and Chile ( Soreng et al. 2003 and onwards; Rúgolo de Agrasar 2012). It has most likely been introduced and naturalized in South America.

Other specimens examined.

Colombia. Boyacá: Munic. Arcabuco, Páramo El Valle, Vereda el Carmen, páramo muy húmedo dominado por Chusquea , pastoreo natural, 5.75425N, 73.3830278W, 3430 m alt., 15 Nov. 2017, S.P. Sylvester 3067b (COL, FMB, K, US); Munic. Duitama, Páramo de Agueros, vía que conduce a vereda de Avendanos, 5.91464N, 73.07114W, 3445 m alt., 28 Oct. 2017, S.P. Sylvester 3047 (FMB, K, US); Munic. Duitama, Páramo de Agueros, semi disturbed páramo in Agueros reserve above ridge- along path running through reserve, 5.91653N, 73.07164W, 3445 m alt., 29 Oct. 2017, S.P. Sylvester 3052 (FMB, K, UPTC, US); Munic. Duitama, Páramo de 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 , no signs of grazing, 5.58389N, 73.053263W, 3970 m alt., 21 Nov. 2017, M. Vorontsova 2198 (FMB, K, US); Munic. Duitama, Páramo de La Rusia, Fina Betania, vereda El Carmen on other side of river, 5.95333N, 73.10864W, 3445 m alt., 30 Oct. 2017, S.P. Sylvester 3060 (FMB, K, US); Munic. Duitama, Páramo de La Rusia, vía que conduce a Vereda de Avendanos, páramo semi-perturbado, pastado por cabras y quemado regularmente hasta hace 1 año, 5.95011N, 73.09097W, 3795 m alt., 1 Oct. 2017, S.P. Sylvester 3004 (COL, FMB, K, US); Munic. Duitama, valley between Guantiva and La Rusia, between Susacon and Onsaga, 2 km towards Onzaga, 6.10091N, 72.48263W, 3292 m alt., 24 Nov. 2017, M. Vorontsova 2304a (FMB, K, US); Munic. Mongua, Páramo de Ocetá, Valle de Laguna Negra, pajonal frailejonal, terreno inclinado en medio del valle, 5.70664N, 72.80361W, 3699 m alt., 29 Nov. 2017, L.E. Cuta-Alarcón 365 (FMB, K, UPTC, US); Munic. Mongui, Páramo de Ocetá, Sector La Pedrisca, Vereda Vallado, potrero con 20 años de abandono dominado por Senecio y Espeletia boyacensis , y gramíneas exóticas, 5.69969N, 72.80892W, 3751 m alt., 30 Nov. 2017, L.E. Cuta-Alarcón 377 (FMB, K, SI, US); Munic. Sotaquira, protected area of Páramo El Valle, day 2 East ridge walk, somewhat disturbed patch of open páramo between patches of Chusquea tessellata [Munro], dominated by Espeletia boyacensis , limited natural grazing, 5.44436N, 73.22089W, 3717 m alt., 16 Nov. 2017, M. Vorontsova 2155 (FMB, K, US).

Notes.

This species is highly variable in terms of its habit, the form of its leaf blades (flat or involute) and ligule (short and obtuse to long and acuminate), and the form of the panicle (panicle branches adpressed and congested when young while open when mature). The combination of open panicle (when mature), lemma with a dorsally inserted awn, and a minute or absent palea are diagnostic for this species.

Similar species.

Agrostis perennans s.l., which can be principally differentiated by the absence of an awn, or if awn present, this being inserted in the upper half of the dorsal surface of the lemma or subapically and to 0.5 mm long. Agrostis pittieri Hack., considered endemic to Costa Rica by Pohl (1980) and Morales-Quirós (2003), also bears close similarity to A. mertensii and may be placed as a synonym of the latter in future research. Hokche et al. (2008) and Dorr (2014) record A. pittieri for Venezuela, with Dorr (2014) stating A. pittieri can be tentatively differentiated by having linear and narrow panicles with green spikelets and lemmas 1.9-2 mm long, while A. mertensii has broadly ovate to lanceolate panicles with purple spikelets and lemmas 2-2.5 mm long. However, these characters’ overlap in specimens studied from throughout the range of A. mertensii .

Figures

Figure 7. Agrostis mertensii A spikelet, lateral view, with floret detached and raised above the glumes B whole plant. Images of Cuta-Alarcon 365 (FMB).