Poa pratensis angustifolia (L.) Lej., Comp. Fl. Belg. 82. 1828.

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 : 47-48

16c. Poa pratensis angustifolia (L.) Lej., Comp. Fl. Belg. 82. 1828. Fig. 17 H, I

Poa angustifolia L., Sp. Pl. 1: 67. 1753. (lectotype: LINN-87.12!, excluding second culm from the left, designated by Soreng 2000: 254).

Description.

Tufts sparse to dense, some shoots clustered; pale green or bluish-gray-green; tillers intra- and extravaginal. Culms 25-80 cm tall. Ligules of lower culm and tiller leaves commonly glabrous abaxially; blades of cauline leaves flag leaf blades folded or involute, with involute margins, moderately thick or thin, moderately thin or soft; sterile shoot blades 10-45 cm long, 0.4-1 mm wide, all involute, like or often distinctly narrower than cauline blades, sparsely pubescent adaxially. Panicles 8-18 cm long, loosely contracted, or open and narrowly pyramidal; rachis with 3-6 branches per node; primary branches ascending to spreading, smooth, or sparsely to densely scabrous; spikelets several to many per branch. Spikelets narrowly lanceolate, not bulbiferous; glumes unequal, infrequently glaucous; lower glumes 1(-3)-veined; upper glumes shorter than or subequaling the lowest lemma; lemmas 2.5-3.5 mm long, finely muriculate, intermediate veins glabrous; paleas scabrous, medially glabrous over the keels, intercostal region glabrous. 2 n = 28, 46, 48, 49-54, 56, 57, 59-66, 72.

Distribution.

This subspecies is native to Eurasia. It is introduced in North America where it is known from Canada, USA, and in Mexico (San Luis Potosí).

Ecology.

The subspecies isintroduced and sometimes is included in pasture grass seed mixes, it tolerates drought better than other subspecies except perhaps subsp. agassizensis.

Specimens examined.

Mexico. San Luis Potosí: 25 mi E of San Luis Potosí on highway 70, 27 May 1979, F.W.Gould 15603 (TAES).

Discussion.

This Poa pratensis subspecies is more drought tolerant than the others, except perhaps subsp. agassizensis. It is most easily recognized by its very fine, relatively firm, involute leaf blades that are adaxially pubescent. This subspecies name is often applied to collections of subsp. pratensis. The latter often has narrow intravaginal leaves but those are softer and adaxially glabrous. According to Stoneberg-Holt’s ( 2004) results, subsp. angustifolia is lower polyploid, and many of the higher counts reported in the literature for this taxon (at least those above 2 n = 56) are possibly referable to subsp. pratensis.

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).