Poa calycina mathewsii (Ball) Refulio, Syst. Bot. 37(1): 130. 2012.

Soreng, Robert J. & Peterson, Paul M., 2012, Revision of Poa L. (Poaceae, Pooideae, Poeae, Poinae) in Mexico: new records, re-evaluation of P. ruprechtii, and two new species, P. palmeri and P. wendtii, PhytoKeys 15, pp. 1-104 : 17-20

5. Poa calycina mathewsii (Ball) Refulio, Syst. Bot. 37(1): 130. 2012. Figs 5 6 N-P

Deschampsia mathewsii Ball, J. Linn. Soc., Bot. 22: 60. 1885. Dissanthelium calycinum subsp. mathewsii (Ball) Soreng, Novon 8(2): 201 1998. Type: Peru, above Caspalta, 14000-14300 ft [4270-4360 m], 22 Apr 1882, J. Ball s.n. (holotype: K!; isotypes: GH!, US-908709! fragm. ex K).

Dissanthelium sclerochloides Steud. ex E. Fourn., Mexic. Pl. 2: 112 1886. Type: Mexico, Nevado de Toluca, 1865-1866, M. Hahn s.n. (lectotype: P!, designated by Soreng 1998: 201; isolectotypes: P!, US-865890! fragm. ex P-Fourn-258).

Dissanthelium semitectum Swallen & Tovar, Phytologia 11: 370 1965.Type: Peru, Junín, Huaron, in clumps on northeastern rock ledges, about 14000 ft [4270 m], 12 Jun 1922, J.F. MacBride & W.Featherstone 1155 (holotype: US-1161061!).

Description.

Gynomonoecious. Perennials; tufted, tufts dense, small, low (mostly 3-8 cm tall), with panicles mostly included among the leaves, pallid green to bluish-grey-green, sub-lustrous; tillers intravaginal (each subtended by a single elongated, 2-keeled, longitudinally split prophyll), without cataphyllous shoots, sterile shoots more numerous than flowering shoots. Culms 4-9 cm tall, erect or ascending, sometimes slightly decumbent or geniculate, leafy, terete, smooth; nodes 0-1, not exerted. Leaves mostly basal; leaf sheaths slightly compressed, smooth, glabrous, lustrous; butt sheaths papery, smooth, glabrous; flag leaf sheaths 1.5-4.5 cm long, margins fused ca. 30% their length, ca. equaling its blade; throats and collars smooth, glabrous; ligules (0.5-)1-2.5 mm long, hyaline, abaxially smooth or scabrous, apex obtuse to acute, entire to dentate, sterile shoot ligules like those of the culm leaves; blades 1-6 cm long, 1.5-3 mm wide (expanded), folded, often with strongly involute margins, moderately thick and firm, abaxially smooth sub-lustrous, veins slightly expressed, margins scabrous, adaxially smooth or moderately to densely scaberulous, apex slender prow-tipped; flag leaf blades 1-6 cm long; sterile shoot blades like those of the culm. Panicles 1.5-2.5(-3) cm long, 0.7-1.1 cm wide, erect, contracted to loosely contracted, mostly included in the foliage, congested to moderately congested, with 10-25 spikelets, proximal internode 0.4-0.7 cm long; rachis with 2-6 branches per node; primary branches sub-erect to ascending, stout, more or less terete, moderately densely stiff scabrous all around; lateral pedicels 1/4-1/2 the spikelet length, smooth or sparsely to moderately scabrous, prickles fine, sometimes sub-ciliolate; longest branches 0.8-1.5 cm, with up to 6 spikelets in the distal 1/2. Spikelets (3-)3.5-6(-5.5) mm long, 2-3 × as long as wide, elliptical in side view, to cunniate at maturity, laterally compressed, not bulbiferous, green, sub-lustrous; florets 2, lower hermaphroditic, upper often pistillate; rachilla internodes terete, 0.2-0.3 mm long, smooth, glabrous; glumes broadly lanceolate, central portion green, margins broadly creamy-white scarious, equal, both exceeding the florets, chartaceous on back, smooth, edges obscurely scaberulous, apex firm, acute, sometimes a bit anthocyanic; both glumes (2.5-)3-6(-5.5) mm long, 3-veined; calluses indistinct, glabrous; lemmas 2.3-2.8 mm long, 3-veined, elliptic to oval, pale green, not lustrous, strongly keeled, keel moderately to densely, and upper 2/3 surfaces lightly scaberulous, intermediate veins absent, margins and apex narrowly and briefly scarious-hyaline, edges mod erately to sparsely scaberulous; apex obtuse to acute, sometimes denticulate in the upper margin; palea keels finely scabrous, between veins smooth or lightly scaberulous. Flowers; lodicules 0.5 mm long, narrowly lanceolate, unlobed; anthers 0.5-1.1 mm long, those of the upper flower vestigial or sometimes poorly formed but not much reduced. Caryopses 1.3 mm long, elliptical in side-view, laterally compressed, slightly sulcate, hilum oval about 0.2 mm long, grain adherent to the palea. 2 n = unknown.

Distribution.

The species occurs in Bolivia and Peru, and in Mexico it is known from the states of Mexico, Puebla, San Luis Potosí, Tlaxcala, and Veracruz.

Ecology.

This species is found on fairly well drained alpine volcanic slopes between 3800-4550 m. Flowering August to September.

Specimens examined.

Mexico. San Luis Potosí: Virlet d’Aoust 1434 (US fragm.). Puebla: Ixtaccihuatl, Oct 1905, C.A.Purpus 1633 (US). Ixtaccihuatl S flank, in circ E of the "portal" N of La Amacuilecatl (Los Pies), 4400-4450 m, 19.15426°N, 98.63072°W, 3 Oct 1987, R.J.Soreng 3317 & N.Soreng (US). falda SO de Ixtaccihuatl, 3800 m, 1 May 1952, E.Matuda 26104 (US). Municipio de San Nicoas de los Ranchos La Joya, Volcán Ixtaccihuatl, 7 km a N de al carretara pavimento a Amecameca, 3920-4000 m, 28 Oct 1976, S.D.Koch 76236 (US). north side of Popocatepetl, 11 Sep 1957, J.H.Beaman 1732 (US). Mexico: Tlaloc, near summit, 4100-4140 m, 22 Aug 1958, J.H.Beaman 2329 (US). Nevado de Toluca, 1865-1866, Hann s.n. (P, US fragm. ex P-STEUD). Nevado de Toluca, 13500 ft [4115 m], (19°06'00"N, 99°45'36"W), bottom of the crater, 01 Sep 1892, C.G.Pringle 4222 (MO not seen, US, US, US); ditto, summit, 4545 m., 09 Oct 1986, P.M.Peterson 04655 & C.R.Annable (US); ditto, on south rim of crater, 8 Sep 1957, J.H.Beaman 1692 (US). Laguna de Sol, 13 miles east of Mex. highway 3 on road to Nevado de Toluca., 4000 m., 08 Oct 1986, P.M.Peterson 4646 & C.R.Annable (US). Tlaxcala: Malinche, North rim of the crater, 4400-4450 m, 10 Aug 1958, J.H.Beaman 2240 (US). Veracruz: Summit of Cofre de Perote, 19°29'42"N, 97°08'55"W, 4140 m, 20 Sep 1997, S.J.Darbyshire 4806 & M. Gonzáles-Ledesma (US).

Discussion.

First reported from Mexico by Fournier (1886) as Dissanthelium sclerochloides , Beetle (1987) accepted Dissanthelium mathewsii Ball as the correct name. Soreng (1998) and Refulio-Rodríguez et al. (2012) concluded there were too many intermediates between this and the smaller and shorter spikeleted Dissanthelium calycina (J. Presl) Kunth, and therefore, treated the taxon as a subspecies or variety. Poa calycina var. calycina and var. mathewsii are known from Bolivia and Peru. Historically, the species was treated within Dissanthelium . However, DNA analyses have confirmed that all elements of that genus belong within Poa ( Refulio-Rodríguez et al. 2012). All but one species formerly placed in Dissanthelium differ from other Poa by having spikelets with two florets, lemmas 3-nerved (rare in Poa ), and glumes that are longer than at least the lowest lemma (a feature that occurs infrequently in other groups of Poa ). Poa calycina belongs to Poa sect. Dissanthelium (Trin.) Refulio (see also Poa thomasii below).

Figures

Figure 5. Poa calycina var. mathewsii (Ball) Refulio. Photo of Purpus 1633.

Figure 6. A-E Poa gymnantha Pilg. A spikelet B lemma and palea C palea D staminode and lodicules (pistillate-flower) E pistil (pistillate-flower) F-I Poa chamaeclinos Pilg. F spikelet G floret H palea I pistil (pistillate-flower) J Poa palmeri Soreng & P. M. Peterson J spikelet K-M Poa strictiramea Hitchc. K spikelet L floret M palea N-P Poa calycina var. mathewsii (Ball) Refulio N spikelet O floret P palea. A-E drawn from Peterson 12863 et al. from Peru F-I drawn from Soreng 3315 & Soreng; J drawn from Peterson 18790 & Valdes-Reyna K-M drawn from Soreng 3204 & Spellenberg N-P drawn from Beaman 1732.