Poa palmeri Soreng & P.M. Peterson, 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 : 41-43

15. Poa palmeri Soreng & P.M. Peterson sp. nov. Figs 6J 15

Type:

Mexico. Nuevo León, Sierra Madre [Oriental] above Monterey [ca 25°38'N, 100°38'W], calcareous ledges, 3000 ft [misprint for 8000 ft; 2440 m], 31 Mar 1906, C.G.Pringle 10212 (holotype: US-462254!♂; isotypes; GH!, MEXU-539725!♂, MO-1770420!♀, MSC, NMC!, NY-431382!, WYAC).

Diagnosis.

Differing from Poa ruprechtii Peyr. by leaf collar margins flared (versus not flared), ligules of upper culm leaves truncate (versus obtuse to acute), flag leaf sheaths fused by an invaginated hyaline membrane for much of the upper fusion length (versus abruptly fused by firmly chartaceous margins), spikelet pedicles elongated and moderately to densely scabrous (versus shorter and usually densely to more coarsely scabrous), distal rachilla internodes usually 1-2 mm long (versus less than 1 mm), lemmas thinly chartaceous, intermediate veins faint to moderately prominent, not extending to near the upper margin, margin and apex fairly broadly scarious-hyaline (versus lemmas chartaceous, intermediate veins prominent, extending nearly to the margin, margin and apex narrowly scarious), anthers 1.6-2.8 (versus 0.7-1.05[-1.25]) mm.

Description.

Trioecious (mostly hermaphroditic, but some pistillate or staminate). Perennials; tufted, sometimes sub-rhizomatous to rhizomatous, tufts dense to loose, generally medium girth and height, green or bluish-grey-green; tillers extravaginal (basally cataphyllous), and/or mainly intravaginal (each subtended by a single elongated, 2-keeled longitudinally split prophyll), with lateral or downward tending, cataphyllous shoots, or without them. Culms (26-)50-70 cm tall, erect or bases slightly decumbent, fairly slender, not branching above the base, leafy, terete or weakly compressed, smooth; nodes 3-4, terete or slightly compressed, 1-2 exerted. Leaf sheaths slightly compressed, smooth or sparsely to infrequently densely scabrous, glabrous or rarely retrorsely hirtellous to strigulose; butt sheaths papery, smooth, glabrous; flag leaf sheaths (5-)7-18 cm long, margins fused 34-65% the length, fused by an invaginated hyaline margin for much of that length, 1.1-3.1 × longer than its blade; collar margins of lower and mid culm leaves usually flared, smooth or scabrous, glabrous or more often ciliate; ligules 0.8-3 mm long, scarious to hyaline, adaxially scabrous or puberulent, upper margins often ciliolate, apices truncate and entire below to obtuse and irregularly dentate/lacerate above, sterile shoot ligules like those of the culm leaves; blades 2-30 cm long, (1.5-)2-3 mm wide, flat and slightly lax to involute and moderately firm, abaxially and adaxially smooth or lightly scabrous over the veins, margins scabrous, narrowly prow-tipped; lower mid-cauline blades the longest, 10-30 cm long, shorter upward, flag leaf blades 27-50 (90)% longer than their sheaths, flag leaf blade 2.3-10.8 cm long; sterile shoot blades similar to cauline blades or more involute. Panicles 6.5-20 cm long, erect, open, usually trapezoidal to pyramidal, sparse to moderately congested, with (18-)40-100 spikelets, proximal internode (2-)3-5 cm long; rachis with (1-)2-4(-5) branches per node; primary branches spreading to eventually reflexed, fairly flexuous, terete to weakly angled, sparsely to moderately scabrous; lateral pedicels 1/2 to equaling the spikelets, moderately to densely scabrous, prickles fine to moderately coarse; longest branches 4-10 cm, with 3-34 spikelets in distal 1/2, loosely arranged. Spikelets 3-8 mm long, to 3.5 × long as wide, lanceolate, laterally compressed (sexually dimorphic - staminate spikelets with more florets, up to 7-9); spikelets infrequently bulbiferous; florets (2-)3-6(-9), pistillate, staminate, or hermaphroditic; rachilla internodes terete, distal internodes terete, exceeding 1 mm long, smooth or lightly scabrous, glabrous; glumes narrow lanceolate, distinctly keeled; lower glumes 1.6-3.5 mm long, 1/2-2/3 as long as adjacent lemmas, 1-veined; upper glumes 2.2-4.9 mm long, 3-veined; calluses dorsally webbed, web scant to distinct, hairs 1-2 mm long, woolly; lemmas 2.6-5 mm long, lanceolate, 5-veined, body thinly chartaceous, distinctly keeled, keels to 1/3-2/3 and marginal veins to 1/5-1/3 sparsely short to long villous, intermediate veins smooth or sparsely scabrous, glabrous, between veins smooth, glabrous, intermediate veins obscure to moderately prominent, not extending to near the margin, margins smooth, broadly scarious-hyaline, smooth, apices acute; paleas scabrous, medially rarely softly puberulent over the keels. between keels narrow (0.3-0.4 mm), muriculate, scabrous to sparsely puberulent. Flowers chasmogamous; lodicules 0.5 mm long, lanceolate, with a narrow lateral lobe; anthers 1.6-2.8 mm long, sometimes late aborted, infrequently vestigial throughout individual plants. Caryopses 1.8-2.1 mm long, elliptical in side-view, sulcus broad and shallow, brown, hilum 0.2 mm long, round, grain adherent to the palea. 2 n = unknown.

Distribution.

The species is endemic to the Sierra Madre Oriental and is found in Coahuila and Nuevo León, Mexico.

Ecology.

This species is found on rocky calcareous substrates in shaded and open forests associated with Pinus , Quercus , and Abies ; between 1750-3760 m. Flowering April through October.

Conservation status.

The species is a regional endemic, known from only 15 collections over 1400 km2.

Etymology. The new species is named for Dr. Edward Palmer (1829-1911), an important early collector for the U.S. Department of Agriculture, known particularly for his work in southwestern USA and northern Mexico, who, in 1880, was the first to collect this plant. We selected the Pringle collection as type because it is widely distributed.

Specimen examined. Mexico. Coahuila: mountains 6 mi east of Saltillo, Feb to Oct 1880, E.Palmer 1366 (GH, NY, US-924987⚥). Sierra de Los Lirios, 2800 m, Jul to Aug 1942 [error for 1924?], E.Lyonnet 3691 (MEXU-379081⚥, 379082⚥). 22 km SE of San Antonio de las Alazanas, southeast of Saltillo, 20 Jul 1963, F.W.Gould 10538A & D. Watson (TAES). Rincòn de María, on Hacienda La Babia, ca. 70 road miles northwest from Múzquiz, 1750 m, 27 Apr 1975, T.Wendt 883 & D.Riskind (LL). Cima de Sierra la Viga, ca. 3600 m, 24 Oct 1984, A.McDonald 1172 & Gomez (TAES⚥). ceja y ladera s de Sierra La Viga, 3700 m, 22 Aug 1986, A.McDonald 2104 (TEX, TEX). Las Vigas, Cañón de la Carbonera, Sierra de Arteaga, 2100-2600 m, 5 Jun 1987, J.A.Villarreal & M.A.Carranza s.n. (MEXU-469611). Sierra La Marta, east of Cerro Moro, 3400 m, 22 Jul 1985, S.Ginzbarg 148, A.Whittemore & A.McDonald (MEXU-666069♀). Sierra Coahuilon, ca. 3400-3500 m, 18 Jun 1985, A.McDonald 1485 & M.H.Cervera (MEXU-1072101⚥). SE of San Antonio de las Alazanas, SE of Saltillo, at end of road near Summit of Coahuilon, 25.2203°N, 100.3305°W, 3120 m, 17 Oct 1989, P.M.Peterson 8390, J.Valdes-Reyna, & J.Villarreal (US-3518353⚥). 51.6 km southeast of Saltillo and 13 km southeast of Jame on road to Sierra La Viga, 25.33°N, 100.579°W, 3240 m, 26 Sep 1990, P.M.Peterson 10053, C.R.Annable & J.Valdes-Reyna (US). Sierra Zapalinamé, east of Saltillo, 25.3468°N, 100.9016°W, 2700 m, 2 Sep 2005, P.M.Peterson 18787 & J.Valdes-Reyna (US-3496160 (DNA voucher, unpublished, distributed as " Poa ruprechtii "); ditto, E of Saltillo, "El Penitente", 25.3468°N, 100.9016°W, 3070 m, 2 Sep 2005, P.M.Peterson 18790 & J.Valdes-Reyna (US-3496160); ditto, along trail from El Cuatro to El Penitente, 25.3383°N, 100.8882°W, 2925 m, 28 Sep 2007, P.M.Peterson 21127, J.M.Saarela, & S.G. Gómez-Pérez (US; DNA voucher, unpublished). Nuevo León: Cerro Potosí, east slope, 2135 m, 9 Jul 1963, R.L.McGregor 385, L.J.Harms, A.J.Robinson, R.delRosario, R.Segal (US-2454930⚥).

Discussion.

A provisional key to 11 species of Poa in northern Mexico (excluding Baja California) is provided in Peterson et al. (2006). In that paper we concluded that Poa ruprechtii , as widely applied, was heterogeneous. However, until we could examine the type of Poa ruprechtii (C. Heller 312) we could not be sure of the application of the name. Here we emend the description of Poa ruprechtii Peyr. s.s., and treat the material of northeastern Mexico as a new species. Poa palmeri has long been confused with Poa ruprechtii ( Fournier 1886, Hitchcock 1913, Beetle et al. 1999, Espejo Serna et al. 2000, Dávila Aranda et al. 2006). Poa palmeri differs in several leaf, panicle, and spikelet characters, and has longer anthers, and the two species do not overlap in geographic range. There is a note on Palmer’s label at US, " Poa ruprechtii Peyr, so named at Kew, S.W. (RJS-presumably Sereno Watson), but scarcely distinct from Poa flexuosa Muhl." (= Poa autumnalis Muhl. ex Elliott of lowlands from the central and southern Appalachians), and a further note; "related to Poa flexuosa " apparently written by A.S. Hitchcock. Interestingly, this name was also applied to the type of Poa ruprechtii at W ( Fig. 16 ). This presumably stems from Peyritsch’s final statement (p. 8) that his new species is like what is now called Poa cuspidata Nutt. (also of the Appalachians), which has sometimes been confused in herbaria with Poa autumnalis . Peyritsch stated, "Scheint mit Poa brachyphylla Schult. ( Poa brevifolia Muhl.) verwant zu sein." The latter two names are synonyms of Poa cuspidata Nutt.

Pringle’s label on the type collection can be read as 3000 ft, but we wonder if this is a printing error as the 3 looks more like an 8 when inspected closely, without the serifs of the 3 that are present in the date and other numbers. Whatever the case is, 3000 ft seems far too low for this species.

The breeding system of Poa palmeri is not clear. We tentatively identify it as trioecious because a few specimens are staminate throughout, a few are pistillate, most are hermaphroditic, but some of the later have late aborted stamens. Possibly sex-expression varies within some individuals between late and early season panicles, as seen in sequential gynomonoecism ( Soreng and Keil 2003).

It is most easily differentiated from Poa strictiramea by having smooth foliage, more developed lemma and callus pubescence, and smoother lemma surfaces.

Figures

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.

Figure 15. Poa palmeri Soreng & P. M. Peterson. A habit B inflorescence C sheath, ligule, blade D spikelet E glumes F floret G callus of floret H lemma dorsal view I palea dorsal and ventral views J stamen K pistil from perfect-flowered plant, with lodicules attached to palea L rudimentary pistil from staminate plant, with lodicules. A-J and L drawn from holotype collection (Pringle 10212) K drawn from Palmer 1366.

Figure 16. Poa ruprechtii Peyr. Photo of holotype collection (Heller 312).