Poa laegaardiana Soreng & P.M. Peterson
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|Poa laegaardiana Soreng & P.M. Peterson|
Ecuador. Province de Bolivar, 66.5 km SW of Ambato on hwy to Guaranda and 2.2 km along road to Facundo Vela, [est. 1.516022 S, 79.007192 W], 4300 m a.s.l., growing on sandy, volcanic soil in Festuca - Calamagrostis [s.l.] grassland, 3 May 1990, P.M. Peterson 8997 & C.R. Annable (holotype: US-3244349!; isotypes: AAU!, MO-3853338!, QCA!).
Differing from Poa gigantea (Tovar) Refulio in having glumes 3/4 to 7/8 as long as the adjacent lemmas (versus glumes about as long or longer than the adjacent lemma), a callus with a sparse, short, dorsal tuft of woolly hairs (versus no web), culms 50-72 cm tall (versus 22-58 cm tall) and spikelets 4.1-4.8 mm long (versus 5-5.5 mm long).
Gynomonoecious. Perennials, densely tufted, without lateral tending shoots or with infrequent short lateral tending shoots, greyish-green, with anthocyanic tinges; tillers extravaginal, erect; culms 50-72 cm tall, erect, culm nodes and internodes, terete, smooth, glabrous, 0 nodes exposed, highest node in lower 1/10 of culm. Leaves concentrated at base; sheaths 14-30 cm long, laterally compressed, slightly keeled, smooth, glabrous, proximal sheaths chartaceous, strongly overlapping at base, butt sheaths papery, smooth, glabrous and inconspicuously shredding with age; uppermost culm sheath to 30 cm long, margins fused ca. 10% their length, ca. 3 –4× longer than their blade; throats and collars, smooth, glabrous; ligules to 3.5-6.6 mm long, of sterile shoots to 3.5 mm long, membranous, abaxially scaberulous, margins decurrent, apicies acute, apex of distal-most sometimes fimbriate; blades to 22 cm long, 1.5--3 mm wide (expanded), uppermost to 8 cm long, firm, stiff, erect, tightly folded to involute, keeled, abaxially smooth or obscurely scaberulous along the veins, adaxially densely scabrous, mostly along the veins on a nearly level surface (aside from the single channels flanking the central vein), apex narrowly prow tipped, acuminate, stiff; sterile shoot blades like those of the culm, crowded, to 22 cm long above the initial cataphylls if any. Panicles 7.6-11.5 cm long, 0.6-1.2 cm wide, contracted, spiciform, erect, narrow, interrupted below with areas along the rachis with no branches, with 50-60 spikelets; proximal internodes 2.5-3.5 cm long, smooth, axis with mostly 2 branches at lower nodes; branches 2.5-3.5 cm long, with up to 12 spikelets crowded in the distal 2/3, appressed (ascending at anthesis), terete to slightly angled, short scabrous mainly along the angles; lateral pedicels mostly 0.5-1 mm long. Spikelets 4.1-4.8 mm long, 2 –2.5× longer than wide, lanceolate, laterally compressed, not bulbiferous, violaceous in part at maturity, florets 2, the upper slightly reduced; rachilla internode above the proximal floret 0.5 mm long, terete, scabrous to hirtellous; glumes 3/4 to 7/8 as long as the adjacent lemma, subequal, lanceolate to oblong, keels smooth or distally obscurely scaberulous, margins distally smooth, apex acute; lower glumes 3-3.5 mm long, 1 (3)-veined; upper glumes 3.4-3.8 mm long, 3-veined; calluses webbed, with a sparse, short, dorsal tuft of woolly hairs to about 1 mm long; lemmas 3.5-4.2 mm long, 5-veined, lanceolate in side-view, violaceous in part, strongly laterally compressed, distinctly keeled, glabrous throughout, keel distally scaberulous or nearly smooth, sides smooth (appearing densely granular due to abundant short-cells), intermediate veins obscure to distinct, margins inrolled below at maturity, narrowly scareous above, edges smooth, apicies acute; paleas 3.3-3.7 mm long, a little shorter than the lemma, texture like the lemma, 2-keeled, the keels distally scaberulous, glabrous between the keels. Flowers pistillate over perfect within the spikelets; lodicules 0.25 mm long, 2, lobed; stamens 3, anthers 1.4-1.6 mm long, light yellow, vestigial in upper floret less than 0.1 mm long; ovary glabrous; caryopses 1.6-2 mm long, elliptical in side-view, brown, translucent, sulcus broad and shallow, hilum ca. 0.15 mm long, round, grain loosely adherent to the palea.
The species is known only from the type collection in Provincia Bolivar, Ecuador.
The species is apparently rare. Google Earth view [26 Mar 2018] of the pass location where the new species was collected in 1990 indicates the area is now covered by small farms.
The specific epithet honors Simon Laegaard (1933-), a renowned Danish Botanist, who has made extensive collections in Ecuador, Greenland and South America.
There are a number gynomonoecious species of Poa occurring in northern South America, Central America and central Mexico but all have loose, open panicles, except the new species and species of Poa sect. Dissanthelium (Trin.) Refulio ( Refulio-Rodriguez et al. 2012). Most of these open-panicled species of Poa supersect. Homalopoa (Dumort.) Soreng & L.J. Gillespie and the new species have glabrous lemmas and a web on the callus with a perfect lower floret and a pistillate upper floret. The new species appears to belong within Poa subg. Poa supersect. Homalopoa ( Giussani et al. 2016). Poa sect. Homalopoa s.str. may be restricted to Eurasia and North America while most species of the New World are placed in sect. Homalopoa s.l. ( Giussani et al. 2016; Soreng et al. 2003).
Poa gigantea ( Poa sect. Dissanthelium ) is morphologically similar to our new species but differs in having glumes longer than or equalling the adjacent lemma, an unwebbed callus, shorter culms 22-58 cm tall and larger spikelets 5-5.5 mm long ( Tovar Serpa 1985; Refulio-Rodriguez 2012). Other Ecuadorian species of Poa with narrow, spikelike panicles includes: P. chamaeclinos Pilg., P. scaberula Hook. f. and P. subspicata . We provide a key to separate these from the new species below ( Hjorth 1991; Soreng and Peterson 2012).
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