Agrostis gigantea Roth, Tent. Fl. Germ. 1: 31. 1788.

Vigosa-Mercado, J. Luis, Delgado-Salinas, Alfonso, Alvarado Cardenas, Leonardo O. & Eguiarte, Luis E., 2023, Revision of the genus Agrostis (Poaceae, Pooideae, Poeae) in Megamexico, PhytoKeys 230, pp. 157-256 : 157

7. Agrostis gigantea Roth, Tent. Fl. Germ. 1: 31. 1788.

Figs 4G , 5G , 17

Triticum giganteum (Roth) Roth, Catal. Bot. 3: 22. 1806.

Vilfa gigantea (Roth) P. Beauv., Ess. Agrostogr. 16: 147. 1812.

Agrostis alba L. var. aristata Spenn., Fl. Friburg. 1: 94. 1825.

Agrostis stolonifera L. subsp. gigantea (Roth) Schübl. & G. Martens, Fl. Würtemberg (ed. 1) 64. 1834.

Agrostis stolonifera L. var. gigantea (Roth) Bréb., Fl. Normandie 390. 1835.

Agrostis alba L. var. gigantea (Roth) G. Mey., Chloris Han. 655. 1836, non Spenner 1825.

Agrostis alba L. subsp. gigantea (Roth) Arcang., Comp. Fl. Ital. 768. 1882.

= Agrostis virletii E. Fourn., Mexic. Pl. 2: 96. 1886. Agrostis virletii E. Fourn. ex Hemsl., Biol. Cent.-Amer., Bot. 3: 552. 1885, nom. nud. Type. Mexico. San Luis Potosí: Prov. de San Luis, 1851, M. Virlet d’Aoust 1345 (lectotype, designated by Vigosa-Mercado (2022a: 2): P (P00740442 [image!]); isolectotypes: P (P00740440 [image!], P00740441 [image!]), US [fragm. ex P] (US00156515 [image!])).

Agrostis stolonifera L. subsp. gigantea (Roth) Maire & Weiller, Fl. Afrique N. 2(XLV): 120. 1953.

Agrostis stolonifera L. subsp. gigantea (Roth) Beldie, Fl. Republ. Socialiste Romania 12: 152. 1972, nom. illeg. hom.*

Type.

Germany. Herb. Albrecht de Haller , A.W. Roth s.n. (lectotype, designated by Widén (1971: 97): G (G00195254 [image!])) .

Description.

Plants perennial, rhizomatous. Tillers extravaginal, with cataphylls. Rhizomes up to 25 cm long. Culms 0.2-1.2 m long, erect, sometimes geniculate, nodes 3-7, glabrous, internodes glabrous. Leaves basal and cauline; sheaths 4.5-13 cm long, usually shorter than the internodes, glabrous or scaberulous; ligules 1-7 mm long, longer than wide, dorsally scaberulous, apices rounded to truncate, erose to lacerate; blades (2-)3.5-20 cm long, 1-8 mm wide, usually at least some blades larger than 5 mm wide, linear, flat, scaberulous on both surfaces. Panicles (9-)13-40 cm long, 4-16 cm wide, open, dense to lax, lanceolate to ovate, exserted from the upper sheaths; branches ascending to spreading, rebranching about or above mid-length, scaberulous, without spikelets near their base or often some inferior branches with spikelets, inferior branches 2.5-15 cm long; pedicels 0.3-3 mm long, ascending to spreading, scaberulous. Spikelets 1.7-3 mm long, greenish to purplish; glumes subequal to unequal, lanceolate to ovate, apices acute to shortly acuminate, 1-veined, scaberulous on the keel, lower glume 1.7-3 mm long, upper glume 1.3-2.8 mm long; callus glabrous or with 2 bunches of few, very short trichomes, inconspicuous; lemmas 1.4-2 mm long, elliptic to oblong, apices entire, acute or sometimes truncate, 3-5-veined, veins inconspicuous or prominent distally, usually unawned; paleas present, 0.5-1.2 mm long, faintly 2-veined, glabrous; anthers 3, 0.7-1.2 mm long. Caryopsis 1-1.5 mm long, elliptic, endosperm solid. 2n= 42 ( Harvey 2007).

Anatomy and micromorphology.

Leaf blades flat in transversal section; adaxial furrows medium-sized, wide; adaxial ribs rounded; keel absent; first order bundles circular in outline, sheath interrupted adaxially and abaxially, abaxial and adaxial sclerenchyma in girders, narrowing towards the bundle; second order bundles circular in outline, sheath interrupted adaxially and abaxially, abaxial and adaxial sclerenchyma in girders, narrowing towards the bundle; intercostal sclerenchyma absent; leaf margins with small to well-developed sclerenchyma caps, rounded; colorless cells absent (Fig. 15F-H ). Lemmas without transversal thickenings, or these poorly developed; prickle hairs absent or scarce (Fig. 7G ).

Distribution and habitat.

Introduced. Agrostis gigantea is native to Eurasia. In the study zone, it has been collected in the USA states of Arizona, California, New Mexico, Texas, and in Mexico City, and the Mexican states of Durango, México, Michoacán, San Luis Potosí, and Sonora (Fig. 18A ). This species has also been reported from Guanajuato, Morelos, and Oaxaca ( Sánchez-Ken 2019), but no specimens from these states were found. Agrostis gigantea grows in disturbed areas, mainly in moist soils of ditches, marshy places and stream edges, between 651-3300 m a.s.l. (Fig. 9J ).

Phenology.

Specimens with spikelets have been collected from June to December (Fig. 10J ).

Commentaries.

It has been reported for other regions that the blades can reach 12 mm wide, spikelets up to 3.2 mm long and lemmas up to 2.2 mm long ( Harvey 2007). This species is often confused with A. bourgaei (see the note under the description of that species). Agrostis gigantea also is similar to A. stolonifera in the paleate spikelets, but differs from it in the rhizomatous habit of the plants and more open panicle (vs. stoloniferous plants, panicle usually contracted in A. stolonifera ).

The rhizomatous plants of Agrostis , with paleate spikelets, were formerly known as A. alba L., a name that was described without a type designation ( Linnaeus 1753). Hitchcock (1905) considered the specimen LINN 84.23 as the type, but this was received by Linnaeus long after 1753 ( Jarvis 2007). Widén (1971) indicates that this name must be typified by a specimen at the Van Royen Herbarium (L0052692), since A. alba was based on the work of Royen (1740), but that specimen corresponds to Poa nemoralis L., so currently A. alba is a synonym of the latter.

Conservation status.

Since Agrostis gigantea is an introduced species in the study zone, its conservation status is considered as Least Concern (LC).

Representative specimens examined.

Mexico. Durango: Municipio Canelas, Las Cebollitas , [25.10273363°N, 106.4441947°W], 2460 m alt., 1 Aug 1990, A. Benítez 1725 (CIIDIR, MEXU, UAMIZ) . México: Municipio Amecameca, km 15 carretera Amecameca-Tlamacas, [19.08516405°N, 98.68113865°W, 3288 m alt.], 2 Oct 1992, A. Miranda and G. Villegas 634 (MEXU [*]). Municipio Isidro Fabela, alrededores de la presa Iturbide, [19.52454734°N, 99.46880154°W], 3300 m alt., 19 Aug 1971, J. Rzedowski 28545 (IBUG [*, **]). Municipio Jilotepec, Jilotepec, [19.96787783N, 99.51665054], 2450 m alt., 27 June 1954, E. Matuda 30961 (MEXU [*, **]). Mexico City: Alcaldía Cuajimalpa, La Venta, Santa Rosa-Contreras, [19.33155°N, 99.31138889°W], 2600 m alt., 29 Jul 1951, E. Matuda 21271 (MEXU [*, **]). Michoacán: Municipio Salvador Escalante, Santa Clara del Cobre , [19.41071944°N, 101.6532583°W], 2150 m alt., E. Pérez 96 (IEB, MEXU). Sonora: Municipio Yécora, 5.2 km W of Yécora on Mex 16, 28.36184916N, 108.961472, 1720 m alt., 1 Jun 1999, A.L. Reina et al. 99-160 (TEX) . USA. Arizona: Graham County, Hospital Flat, Pinaleno Mountains , 32.6651°N, 109.877°W, 700 m alt, 7 Sep 1980, C.E. Jenkins and G. Yatskievych 3120 (ASU). California: San Diego County , Cuyamaca Rancho State Park , Cuyamaca Peak , 1 mi E of highway 79, beside Fern Flat Fire Road (unpaved), 0.5 mi SE of intersection with Lookout Fire Road and 0.8 air mile ENE of summit, 32.9487°N, 116.5935°W, 1586 m alt., 18 Sep 2008, L. Hendrickson 3272 (SD). New Mexico. Socorro County , Bosque del Apache refuge, San Antonio , [33.917844°N, 106.865859°W], 651 m, 7 Dec 1940, L. Lee s.n. (UNM). Texas: Brewster County , along creek from Boot Springs toward Boot , Chisos Mountains , [29.2724465°N, 103.2657998°W], 2065 m alt., 26 Aug 1937, B.H. Warnock 1039 (MICH). See Suppl. materials 2, 3 for additional examined specimens .

Figures

Figure 4. Florets of Agrostis species observed with SEM A A. bourgaei B A. calderoniae C A. capillaris D A. elliottiana E A. exarata F A. ghiesbreghtii G A. gigantea H A. hyemalis I A. laxissima J A. microphylla K A. pallens L A. perennans M A. scabra N A. stolonifera O A. subpatens P A. subrepens Q A. tolucensis R A. turrialbae S A. variabilis. Scale bars: 0.3 mm.

Figure 5. Calluses of Agrostis species observed with SEM A A. bourgaei B A. calderoniae C A. capillaris D A. elliottiana E A. exarata F A. ghiesbreghtii G A. gigantea H A. hyemalis I A. laxissima J A. microphylla K A. pallens L A. perennans. Scale bars: 50 μm.

Figure 7. Lemma surface of Agrostis observed with SEM A A. bourgaei B A. calderoniae C A. capillaris D A. elliottiana E A. exarata F A. ghiesbreghtii G A. gigantea H A. hyemalis I A. laxissima J A. microphylla K A. pallens L A. perennans. Scale bars: 15 μm.

Figure 9. Elevation histograms of Agrostis species A all records B native species C introduced species D A. bourgaei E A. calderoniae F A. capillaris G A. elliottiana H A. exarata I A. ghiesbreghtii J A. gigantea K A. hyemalis L A. idahoensis M A. laxissima N A. microphylla O A. pallens.

Figure 10. Phenology histograms of Agrostis species A all records B native species C introduced species D A. bourgaei E A. calderoniae F A. capillaris G A. elliottiana H A. exarata I A. ghiesbreghtii J A. gigantea K A. hyemalis L A. idahoensis M A. laxissima N A. microphylla O A. pallens.

Figure 15. Leaf blade anatomy in transversal section of Agrostis species, in general view, and details of lateral bundles A - C A. exarata D - E A. ghiesbreghtii F - H A. gigantea I - K A. hyemalis. Scale bars: 0.1 mm.

Figure 17. Agrostis gigantea A whole plant B ligular area C spikelet D floret, abaxial view, E floret, adaxial view F palea. Based on Rzedowski 28545 (IBUG). Scale bars: 3 cm (A); 2 mm (B); 0.5 mm (C); 0.3 mm (D, E); 0.2 mm (F).

Figure 18. Map of known geographic distribution of Agrostis species, based on herbarium specimen data A A. gigantea B A. hyemalis C A. idahoensis D A. laxissima E A. microphylla F A. pallens.