Poa pratensis alpigena (Lindm.) Hiitonen, Suom. Kasvio 205. 1933.

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 : 47

16b. Poa pratensis alpigena (Lindm.) Hiitonen, Suom. Kasvio 205. 1933. Fig. 17 D-G

Poa alpigena Lindm., Sv. Fanerogamfl. 91. 1918. Poa pratensis var. alpigena Fr., Herb. Norm. 9: 93. 1842, nom. illeg. superfl. Poa pratensis var. alpigena Fr. ex Blytt., Norges Fl. 1: 130. 1861, nom. illeg. superfl. Poa pratensis var. iantha Laest., Kongl. Vetensk. Acad. Handl. 1822: 329. 1822. Type: Scandinavia: in insula Gammelgarden et Rosbacken juxta Quickjock, Lule Lappmark, Laestedius s.n. (syntypes: S-6651, S-6670, UPS-3 (herb. Hartmann), UPS-4 (herb. Wahlenberg).

Poa oligeria Steud., Syn. Pl. Glumac. 1: 426. 1854. Type: Chile: Sandy Point Magellan, Dec, W.Lechler 1192 (isotypes: LE!, S-03-2215!, US-81727! ex W, US-946978! fragm. ex LE, W-243018!).

Description.

Tufts sparse, or all shoots solitary; green (often anthocyanic) tillers mainly extravaginal. Culms 15-70 cm tall. Blades of cauline leaves flag leaf blades usually folded, thin, soft; sterile shoot blades less than 15 cm long, 1-3.6 mm wide, flat or folded, usually sparsely pubescent adaxially. Panicles 3-13(-20) cm long, contracted or narrowly pyramidal, expanding well after emergence from the sheath; rachis with (1-)2-6(-7) branches per node; primary branches steeply ascending to eventually spreading or somewhat reflexed, smooth or lightly scabrous; longest branches 1-6 cm, with 5-15 spikelets. Spikelets 4-6.5 mm long, narrowly lanceolate, not bulbiferous; glumes unequal, glaucous or not; lower glumes 1-3-veined; upper glumes subequaling the lowest lemma; lemmas 2.5-3.5 mm long, smooth or finely muriculate, intermediate veins frequently sparsely to moderately densely short villous; paleas scabrous, medially frequently softly puberulent over the keels, intercostal region glabrous, or rarely sparsely hispidulous. 2 n = 28, 32, 35, 42, 43, 48, 50, 52, 53, 56, 60, 62, 63, 64, 67-82, 84, 86, 88, 89, 92, ca. 94, ca. 124, 127.

Distribution.

The subspecies is circumboreal and in North America occurs in Canada, Greenland, USA, and Mexico (Nuevo León).

Ecology.

This subspecies is found in boreal to alpine forests, and it tolerates frigid conditions.

Conservation status.

This native subspecies is common across Canada, and uncommon in the Rocky Mountains south of Colorado, and locally uncommon in Mexico.

Specimens examined.

Mexico. Nuevo León: localizado en Galeana, Cerro el Potosi, 20°52'23"N, 100°13'48"W, 3650 m, 15 Aug 1998, Ing.M.Castillo-B. 345 & Ing.J.Garza-C. (MEXU-1072117 & MEXU 999120, p.p. "a", p.p. "b" is Poa mulleri , on both sheets, fide RJS).

Discussion.

Poa pratensis subsp. alpigena is circumboreal and native to the New World in the arctic, alpine, subalpine, and boreal forests ( Soreng 2007). This subspecies is recognizable in plastid DNA data (due to a deletion in trn-TLF) and nrDNA sequences as distinct from other subspecies so far evaluated ( Gillespie et al. 2005, 2007). In the lower 48 states of USA, Poa pratensis subsp. alpigena occurs at scattered locations as far south as northern Arizona and New Mexico in alpine and subalpine habitats. This subspecies also occurs in Tierra del Fuego, Chile (see type of Poa oligeria ). This is the first report of this subspecies for Mexico, where it is probably best considered an interglacial period relict from glacial expansions. It can be separated from the other subspecies by its loose rhizomatous habit, small spikelets, narrow leaves, and narrow (often only slightly spreading) panicles. In North America, it usually has some scant hairs on the intermediate veins of the lemmas and on the palea keels. Several other specimens, particularly from Orizaba, approach this subspecies (see those under subsp. pratensis annotated as "toward alpigena ").

Figures

Figure 17. Poa pratensis L. A-C Poa pratensis subsp. agassizensis (B. Boivin & D. Loeve) Roy L. Taylor & MacBryde A habit B sheath, ligule, blade lateral view C branch segment with spikelets D-G subsp. alpigena (Lindm.) Hiitonen D habit E inflorescence F branch segment with spikelets G palea H, I subsp. angustifolia (L.) Lej. H habit I branch segment with spikelets. Drawings from Soreng (2007).