Poa fendleriana fendleriana

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 : 27-28

8b. Poa fendleriana fendleriana Fig. 8 C-G

Description.

Leaf collars often scabrous or hispidulous near the throat; ligules of middle cauline leaves 0.2-1.2(-1.5) mm long, not decurrent abaxially scabrous, upper margin usually scabrous or ciliolate, apices truncate to rounded; sterile shoot blades usually scabrous or softly puberulent adaxially. Spikelet rachilla usually smooth and glabrous; lemmas long villous on keels and marginal veins, between veins glabrous or infrequently softly puberulent; palea keels and between keels infrequently puberulent. 2 n = 56.

Distribution.

The subspecies is found throughout the range of the species, but is rare to absent from much of the westernmost part of the USA range. In Mexico the subspecies is found in Baja California, Chihuahua, Coahuila, and Sonora.

Ecology.

Where the ranges of the subspecies overlap this subspecies often occurs in slightly drier and more open habitats than Poa subsp. albescens, and more mesic and cooler habitats than Poa . subsp. longiligula. In Mexico this subspecies can tolerate some disturbance as most of the plants are apomictic, except in Coahuila. The subspecies is found in canyons and rocky slopes, from upper arid grasslands (margins) and chaparral of with scrubby species of Quercus , Arbutus , Juniperus , Vaqualina , and Cercocarpus to Hudsonian coniferous forests. Like Poa fendleriana subsp. albescens, this subspecies is primarily restricted to regions with summer monsoons and some winter snows, and ranges from 1900-2200 m. Flowering in spring.

Specimens examined.

Mexico. Baja California: 4.5 mi S of summit of Cerro 1905, Portezuelo de Jamau, 31°34'N, 115°36'W, 1900 m, 20 Apr 1974, R.Moran 21232 (TAES♀, WYAC♀ intermediate between Poa fendleriana subsp. fendleriana and longiligula, pubescent rachilla, short truncate ligule, probably apomictic). Sierra Juarez, Hansen's Ranch, 21 Jun 1885, C.R.Orcutt 1276a (DS, US♀). Chihuahua: Barranca del Cobre, SE of Creel 28 mi, N of Rio Urique crossing, ca. 7000ft [2135 m], ca. 27.507°N, 107.498°W, 14 Apr 1984, R.J.Soreng 2312 & R.W.Spellenberg (US, population sample: 10♀ 9 subsp. fendleriana; 1 subsp. albescens); ditto, ca. 25 mi SE Creel, ca. 27.534°N, 107.508°W, 2313 (US, population sample: 2♀). N of Basuchil, ca. 10 mi NW of Miñaca, loose crumbling red clay on dry ravine side, near ditch, plateau, arid grassland, 2200 m, 8 May 1929, Y.Mexia 2511 (CAS♀, MO♀). Tomachic, 4.2 mi E on road from La Junta to Yecora, ca. 7000 ft [2135 m], 28.375°N, 107.7865°W, 13 Apr 1984, R.J.Soreng 2306b & R.W.Spellenberg (US, population sample: 24♀ subsp. fendleriana, 2 n = 59; 1 subsp. albescens). S of Rancho La Consolacion, canyon in north face of Sierra Rica, 29°12'N, 104°7'W, 1400-2000 m, 3 May 1973, M.C.Johnston, T.L.Wendt & F.Chiang-C. 10776A (LL♀ toward subsp. albescens); ditto, 10773C (LL♀); ditto, 10777 (LL♀). Coahuila: Sierra del Carmen, south peaks of range, NW side of upper Carboneras Canyon, 28°57'N, 102°34'W, 2100 m, 2 Apr 1974, T.Wendt 125, E.Lott & D.Riskind (TEX♂). Municipio de Ocampo, east side of Sierra del Carmen, 28°53'N, 102°28'W, 5200 ft [1590 m], 8 May 1981, D.H.Riskind 2391 (TEX♀).

Discussion. This is the most widespread but least common subspecies of Poa fendleriana in Mexico. Staminate plants are rare or absent, except in Coahuila where a staminate plant has been collected. Poa fendleriana subsp. fendleriana intergrades with Poa fendleriana subsp. albescens in Chihuahua and in southeast Arizona and southwest New Mexico.

Figures

Figure 8. Poa fendleriana (Steud.) Vasey. A, B Poa fendleriana subsp. albescens (Hitchc.) Soreng A ligule B floret C-G subsp. fendleriana C habit D inflorescence E ligule F spikelet G floret H, I subsp. longiligula (Scribn. & T. A. Williams) Soreng H ligule I floret. Drawings from Soreng (2007).