Agrostis tolucensis Kunth, in Humb., Bonpl. & Kunth, Nov. Gen. Sp. 1: 135. 1816.

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

18. Agrostis tolucensis Kunth, in Humb., Bonpl. & Kunth, Nov. Gen. Sp. 1: 135. 1816.

Figs 4Q , 30E , 36

= Agrostis virescens Kunth, in Humb., Bonpl. & Kunth, Nov. Gen. Sp. 1: 135-136. 1816. Agrostis tolucensis Willd. ex Steud., Syn. Pl. Glumac. 1: 164. 1854, nom. inval., pro syn. Type: Mexico. State of México: in planitie Tolucana, A. Humboldt and A. Bonpland s.n. (holotype: P (P00669395 [image!]); isotypes: LE-TRIN, P (P00136912 [image!], P00740428 [image!], P00740429 [image!], P00740430 [image!])).*

Type.

Mexico. State of México: crescit in apricis, aridis regni Mexicani, prope urbem Toluca et Islahuaca [Ixtlahuaca], 1380 hexap. alt., A. Humboldt and A. Bonpland s.n. (holotype: P (P00669394 [image!]); isotypes: P (P00136913 [image!]), P00136914 [image!], P00136915 [image!], P00740426! [image!]) , US [fragm. ex P] ( US 00156505 [image!]).

Description.

Plants perennial, caespitose, or shortly rhizomatous. Tillers extravaginal and intravaginal, with cataphylls. Rhizomes if present, up to 1 cm, ascendent. Culms 5-30(-60) cm long, erect, nodes 1-3, glabrous, internodes glabrous. Leaves mostly basal or basal and cauline; sheaths 1-10 cm long, the lower ones longer than the internodes, the upper ones shorter, glabrous or scaberulous; ligules 2-5(-6) mm long, longer than wide, dorsally scaberulous, apices acute to truncate, erose or lacerate; blades 3-10(-19) cm long, 0.5-3(-4) mm wide, filiform to linear, conduplicate to involute, sometimes flat, scaberulous on both surfaces. Panicles (3-)5-12 cm long, (0.3-)0.5-1 cm wide, contracted, dense, spiciform, linear to lanceolate, often interrupted at the base, often partially included in the upper foliage sheats; branches appressed, rebranching below mid-length, scaberulous, with spikelets near their base, inferior branches up to 3 cm long; pedicels 0.5-3 mm long, appressed, scaberulous. Spikelets 2-3(-3.6) mm long, greenish to purplish; glumes subequal to unequal, lanceolate, apices acute to shortly acuminate, 1-veined, scaberulous on the keel, lower glume 2-3(-3.6) mm long, upper glume 1.8-2.8(-3.4) mm long; callus pubescent, with 2 bunches of trichomes; lemmas 1.2-2 mm long, elliptic, apices toothed, 5-veined, veins prominent, awned near the base, sometimes above mid-length, rarely awnless, awn 1.5-3.5 mm long, geniculate, reaching the lemma apices; paleas absent or up to 0.2 mm long; anthers 3, 0.5-1 mm long. Caryopsis 0.7-1.5 mm long, elliptic; endosperm soft to solid. 2n= 28 ( Pohl and Davidse 1971).

Leaf anatom y. Leaf blades involute to v-shaped in transversal section; adaxial furrows deep, narrow; adaxial ribs rounded to triangular; keel absent; first order bundles circular in outline, sheath not interrupted, abaxial and adaxial sclerenchyma in strands; second order bundles circular in outline, sheath not interrupted, abaxial and adaxial sclerenchyma; intercostal sclerenchyma present, abaxial; leaf margins with well-developed sclerenchyma caps, rounded; colorless cells absent (Fig. 37A, B ). Lemmas with transversal thickenings irregular to oblong, wider than the unthickened portion of the wall; prickle hairs abundant (32E).

Distribution and habitat.

Agrostis tolucensis is distributed from northern Mexico to Chile. In the study zone, it has been collected in Mexico City, and the Mexican states of Chiapas, Durango, Guerrero, Hidalgo, Jalisco, México, Michoacán, Morelos, Oaxaca, Puebla, Tlaxcala, and Veracruz; in the Guatemalan departments of Sacatepéquez and San Marcos (Fig. 26F ). It has also been reported from the Mexican states of Colima, Guanajuato, and San Luis Potosí ( Villaseñor 2016; Sánchez-Ken 2019), but no specimens from these states were found. Agrostis tolucensis grows in open areas of temperate forests with Abies , Pinus , and Quercus , and alpine grasslands, between 1330-4520 m a.s.l. (Fig. 27F ).

Phenology.

Specimens with spikelets have been collected year round, but most of them between the months of July and November (Fig. 28F ).

Commentaries.

It has been reported that South American populations of this species develop long rhizomes (e.g. Renvoize 1998). This species is often confused with A. exarata and A. subpatens (see the notes under the description of these species). Agrostis tolucensis is a variable species, and several infraspecific taxa have been described, none of which are recognized in this work. In the study zone, at least three forms have been observed, but there is a continuous interval of variation in the populations of this species: 1) small plants with narrow leaf blades and panicles shortly exceeding the foliage, 2) larger plants with narrow leaf blades and panicles long-exserted from the foliage, 3) larger plants with broader leaf blades, more open panicles, and lemmas with awn inserted above mid-length of the lemma. The plants of the latter form have been called A. virescens , but they fit well in the continuous interval of variation of the populations. This species is also confused with A. meyenii Trin. (see the note under excluded species).

Conservation status.

Agrostis tolucensis is a common and widespread species in the study zone. It is represented by 244 collections, with several populations occurring in 17 protected areas. The EOO is 439,417 km2 and the AOO is 432 km2. Following the IUCN criteria, the preliminary assessment category is Least Concern (LC).

Representative specimens examined.

Guatemala. San Marcos: Municipio Sibinal, Volcan Tacana , 500 m al E de Talquián, 15.13055556°N, 92.10694444°W, 4028 m alt., 24 May 2000, N. Gallardo et al. 8851 (MEXU) . México. Chiapas: Municipio Unión Juárez, SE side of the summit of Volcán Tacaná, [15.09306218°N, 92.08369755°W], 3600 m alt., 10 Nov 1972, D.E. Breedlove 29340 (MEXU [*], MO); cráter del Volcán Tacaná, [15.09306218°N, 92.08369755°W], 4000 m alt., 9 Oct 1987, E. Martínez 20869 (MEXU [*]). Durango: Municipio San Dimas, 3 mi S of Guachichiles, upper slopes of cerro Huehento, 24.0786°N, 105.743°W, 3078-3249 m alt., 30 Sep 2008, P.M. Peterson and J.M. Saarela 22445 (CAN, US). Guerrero: Municipio General Heliodoro Castillo, cerro Teotepec, [17.46666667°N, 100.2166667°W], 3200 m alt., 17 Oct 1999, E. Domínguez 1200 (FCME [*]), 5 Dec 1993, M. González and C. Catalán 564 (CHAPA, MEXU). Hidalgo: without municipality, pasando desviación a Pachuca, autopista a México, 19 Jul 1976, J.J. Soto s.n. (IBUG). Jalisco: Municipio Ciudad Guzmán, 2 km antes de llegar a La Casita, camino El Refugio-Nevado de Colima, 2860 m alt., 3 Feb 1994, J. Reynoso 1735 (CIIDIR, IBUG). Municipio San Gabriel, N slopes of Nevado de Colima, [19.60110761°N, 103.5808018°W, 3000 m alt.], 19 Sep 1980, A.A. Beetle and R. Guzmán M-5380 (IBUG, MEXU [*]) . Mexico: Municipio Amecameca, La Joya de Alcalican, pies de Iztaccíhuatl, [19.141667°N, 98.675°W], 3950 m alt., 23 Nov 1975, L. Alonso 66 (CHAPA, IBUG, MEXU); SW del Volcán Iztaccíhuatl, 1.5 km al SE de La Joyita, 19.13291667°N, 98.64144444°W, 3997 m alt., 15 Nov 2012, R. Hernández-Cárdenas and L. Arredondo-Amezcua 867 (MEXU [*]); km 20 carretera Amecameca-Tlamacas, [19.0917039°N, 98.67702965°W, 3402 m alt.], 2 Oct 1992, A. Miranda and G. Villegas 650 (MEXU [*]); La Joya de Alcalican , extremo SW del Iztaccíhuatl, [19.152778°N, 98.673333°W], 3900 m alt, 26 Nov 1978, H.J. Soriano 116 (ASU, CIIDIR, MEXU [*], XAL). Municipio Zinacantepec, camino al Nevado, [19.1225°N, 99.77888889°W], 3200 m alt., 1 Oct 1992, A. Miranda et al. 598 (MEXU [*, **]). Mexico City, Alcaldía Tlalpan, volcán Pelado, [19.151°N, 99.2171°W], 3100 m alt., 1 Jul 1985, A. Miranda et al. 25 (MEXU). Michoacán: Municipio Angangeueo, alrededores del Llano de las Papas, [19.65618889N, 100.2717278], 3200 m alt., 9 Oct 1988, J. Rzedowski 47403 (CHAPA, CIIDIR, IBUG, IEB, MEXU [**], XAL). Morelos: Municipio Huitzilac, Zempoala, [19.05034984°N, 99.31696647°W, 2812 m alt.], 1938, E. Lyonnet 2497 (MEXU, US). Municipio Oaxtepec, Oaxtepec, [18.90219847°N, 98.96287658°W], 1333 m alt., Aug 1952, F. Gallegos 438 (MEXU). Oaxaca: Municipio San Miguel Amatlán, 8.3 mi N of San Cualimojoyas on road towards Santa Maria Yavesia, 17.1819°N, 96.4445°W, 2794 m alt., 20 Sep 2008, P.M. Peterson and J.M. Saarela 22308 (US). Puebla: Municipio Atzitzintla, Sierra Negra, SW of Pico de Orizaba, summit of mountain, [18.98528°N, 97.310745°W], 4520 m alt., 10 Sep 1958, J.H. Beaman 2506 (MEXU, US). Municipio San Nicolás de los Ranchos, 6 km al SE de Paso de Cortés, brecha a Xalitzintla , [20.18°N, 98.44°W], 3400 m alt., 14 Sep 1988, P. Tenorio 15092 (MEXU, TEX); Buenavista, 5 km al E de Xalitzintla, [19.1°N, 98.55°W], 3300 m alt., 15 Feb 1988, P. Tenorio 15099 (MEXU [**]). Tlaxcala: Municipio Huamantla, volcán La Malinche, 4200 m alt., 4 Nov 1988, R. Acosta 2556 (CIB, MEXU [*]); parte alta de La Malinche, [19.25666667°N, 98.02833333°W], 3500 m alt., 7 Oct 1993, R. Hernández 96 (CIIDIR, MEXU). Veracruz: Municipio Perote, Cofre de Perote , 500 m al NO de la estación de televisión, [19.496389°N, 97.151389°W], 4030 m alt., 10 Sep 1992, B.V. Hernández 66 (MEXU [*], CHAPA, CIB, XAL). See Suppl. material 2 for the full list of 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 26. Map of known geographic distribution of Agrostis species, based on herbarium specimen data A A. perennans B A. scabra C A. stolonifera D A. subpatens E A. subrepens F A. tolucensis.

Figure 27. Elevation histograms of Agrostis species A A. perennans B A. scabra C A. stolonifera D A. subpatens E A. subrepens F A. tolucensis G A. turrialbae H A. variabilis.

Figure 28. Phenology histograms of Agrostis species A A. perennans B A. scabra C A. stolonifera D A. subpatens E A. subrepens F A. tolucensis G A. turrialbae H A. variabilis.

Figure 30. Calluses of Agrostis species observed with SEM A A. scabra B A. stolonifera C A. subpatens D A. subrepens E A. tolucensis F A. turrialbae G A. variabilis. Scale bars: 50 μm.

Figure 36. Agrostis tolucensis A whole plant B ligular area C spikelet D floret, abaxial view. Based on Calzada 5707 (MEXU). Scale bars: 3 cm (A); 1 mm (B); 0.5 mm (C); 0.3 mm (D).

Figure 37. Leaf blade anatomy in transversal section of Agrostis species, in general view, and details of lateral bundles. A, B A. tolucensis C, D A. turrialbae E, F A. variabilis. Scale bars: 0.1 mm.