Poa seleri Pilg., in T. Loesener, Verh. Bot. Vereins Prov. Brandenburg 51(Abhandl.): 17. 1909.

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 : 60-62

20. Poa seleri Pilg., in T. Loesener, Verh. Bot. Vereins Prov. Brandenburg 51(Abhandl.): 17. 1909. Figs 13 E-H 21

Type:

Guatemala, Quezaltenango, und Sololá, Bergwold in Totonicapam und Los Encuentros, 25 Sep 1896, E.Seler 2360 (lectotype: US-1389285! designated here; isotypes: BAA-2693! fragm. ex B, GH!). Poa guatemalensis Hitchc. Proc. Biol. Soc. Wash. 40: 81-82. 1927. Type: Guatemala, [Sacatepequez], Volcano Agua, in shade, medium altitude, 2000-3500 m, 5 Dec 1911, A.S.Hitchcock 9115 (holotype: US-924985!). Poa tacanae Swallen, Contr. U.S. Natl. Herb. 29(9): 399 1950. Type: Guatemala, San Marcos, Volcán Tacaná, on wooded lower slopes between Sibinal and summit of Volcán Tacaná, 2500-4400 m, 19 Feb 1940, J.A.Steyermark 36083 (holotype: F-1059917; isotype: US-2236477! fragm. & photo ex F).

Description.

Hermaphroditic. Perennials; tufted, sometimes sub-rhizomatous, tufts loose, narrow girth, low to moderate height, delicate, green; tillers extravaginal (basally cataphyllous), with or without lateral or downward tending, cataphyllous shoots. Culms (20-)18-65(-95) cm tall, erect or weakly ascending, sometimes weakly geniculate, sometimes decumbent at the base, slender, leafy, terete, smooth or more often scabrous (especially below the mid- and upper nodes); nodes 3-4, 1-3 exerted. Leaf sheaths compressed, (smooth) scabrous, glabrous; butt sheaths becoming papery to somewhat fibrous, bases of butt sheaths glabrous; flag leaf sheaths 4-15 cm long, margins fused 40-53% their length, 2.3-6.5 × longer than its blade; throats and collars smooth or scabrous, glabrous, collars often flared; ligules (0.5-)0.8-3 mm long, scarious-hyaline, abaxially smooth or scabrous, glabrous, apex obtuse to acute; blades 5-20 cm long, (1-)1.5-3 mm wide, flat, thin, often lax, abaxially with veins closely spaced and expressed, smooth or lightly to moderately scabrous, margins proximally smooth, distally scabrous, adaxially lightly to moderately scabrous, apex slender prow-tipped; flag leaf blades 2-7 cm long. Panicles (4-)6.5-15 cm long, nodding, open, slender (to 5 cm wide), axis somewhat flexuous, moderately congested to sparse, with 25-100 spikelets, peduncles scabrous, proximal internode 0.9-3.5 cm long; rachis with 1-2(-3) branches per node; primary branches spreading to reflexed, or pendulous, slender, flexuous, terete to slightly angled, proximally smooth or sparsely scabrous, distally moderately scabrous on the angles and sparsely off them; lateral pedicels less than 1/2 the spikelet length, sparsely to moderately scabrous, prickles coarse or moderately coarse; longest branches 1.5-4 cm, with 5-10 spikelets loosely arranged in the distal 2/3-1/2. Spikelets 3.2-5(-5.5) mm long, 3-3.5 × as long as wide, lanceolate, laterally compressed, not bulbiferous, florets 2-3(-4), hermaphroditic; rachilla internodes terete, often visible from the side, regularly (0.5-)0.7-0.9 mm long, slender, smooth, glabrous; glumes green to anthocyanic, strongly unequal, distinctly keeled, keels scabrous, margins narrowly scarious-hyaline, apex acute to acuminate; lower glumes 0.6-1.8(-2) mm long, 1-veined, subulate to slightly sickle shaped, 1/4-1/2 the length of the proximal lemma (rarely longer and narrowly lanceolate); upper glumes 1.5-2.5 mm long, mostly 2-3 × as wide as the lower one, 3-veined; calluses glabrous; lemmas 3.1-4.1 mm long, 5-veined, 5-veined, lanceolate, body chartaceous, green, sometimes apically with a slight to prominent anthocyanic band, exceeded by a slight bronzy band; keeled, glabrous, keel and marginal veins smooth or distally lightly scabrous, between veins distally smooth (faintly muriculate) or distally sparsely scaberulous, intermediate veins faint to distinct, margins and apex very narrowly scarious-hyaline, edges scaberulous, apex entire, acute; paleas distinctly shorter to equaling their lemma, glabrous, keels smooth or sparsely scabrous, between keels smooth. Flowers weakly chasmogamous; lodicules 0.4 mm long, lanceolate to broadly lanceolate, without a lobe; anthers 0.4-0.8 mm long. Caryopses 1.5-1.8 mm long, elliptical in side-view, slightly laterally compressed, pale greenish-brown, sulcus distinct, hilum 0.2 mm long, oval, grain adherent to the palea. 2 n = unknown.

Distribution.

The species is found in Guatemala and Mexico (Chiapas).

Ecology.

In Mexico (Chiapas) the species occurs in cool temperate forests between 2700-3600 m. Flowering September to December.

Conservation status.

The species is rare in Mexico and is known from only three collections, but is not rare in Guatemala (14 collections seen from departments of Huehuetenango, Quezaltenango, San Marcos, Sololá, Sacatepéquez, Totonicapán).

Specimens examined.

Mexico. Chiapas: Municipio Motozintla de Mendoza, 2700 m, 24 Nov 1981, D.E.Breedlove 55829 ["1"; "2" = Peyritchia sp.; fide and subnumbered by RJS 2011] (MO-2997613). Municipio Unión Juárez, summit of Volcán Tacaná, ca. 15.131°N, 092.108°W, 3600 m, 10 Nov 1972, D.E.Breedlove 29381 (DS, MO, TAES). Unión Juárez, 3600 m, 10 Nov 1974, D.E.Breedlove 29364 (MO).

Discussion.

The distribution for this species given by Espejo Serna et al. (2000) and Dávila Aranda et al. (2006) is in error, probably a result of confusion with other species. The salient differences purported to discriminate between Poa tacanae and Poa seleri , respectively, are: rhizomes present versus absent; blades 1-2 mm versus 2-3 mm wide; ligules 0.5-1 mm, versus 2-3 mm long; panicles 4-8 mm versus 7-19 cm long, with 1-2 versus 2-4 branches; spikelets 4.5-5.5 mm versus 3.2-4.5 mm long, lower glumes 1.8-2 mm versus 1.1-1.4 mm long, upper glumes 2-2.5 mm versus 1.8-2 mm, and lemmas 3.3-3.7 mm versus 2.2-2.7 mm long ( Pohl and Davidse 1994). All of these character state ranges overlap between these two species. For example, Beaman 3191 from the type locality of Poa tacanae , is clearly loosely tufted with lateral tending shoots has characteristics that overlap with Poa seleri . Moreover, in collections with intact bases, the habit is evidently loose, while all other features point to Poa seleri . Collections of both taxa from high elevations have spikelets that are elongated (rachillas exposed in side view), with short, narrow, 1-veined lower glumes, glabrous florets, and anthers 0.4-0.8 mm long. Swallen’s holotype of Poa tacanae is immature (US fragm. and photo), and the spikelets are narrower than they would be at maturity. These collections are considered to be high elevation forms of Poa seleri . The type and isotype of Poa seleri at B were destroyed (Hildemar Scholz, pers. comm. 2012), thus we take up the US isotype as lectotype.

Figures

Figure 13. A-D Poa mulleri Swallen A spikelet B floret C palea D pistil E-H Poa seleri Pilg. E spikelet F floret G palea H pistil I-L Poa scaberula Hook. f. I spikelet J floret K palea L pistil M-O Poa orizabensis Hitchc. M spikelet N floret O palea P-R Poa ruprechtii Peyr. P spikelet Q floret R palea. A-D drawn from Beaman 4470 E-H drawn from deKoninck 134 from Guatemala I-L drawn from Peterson 11087 et al M-O drawn from Soreng 3314 & Soreng P-R drawn from Davidse 9771.

Figure 21. Poa seleri Pilg. Photo of lectotype collection (Seler 2360).