Poa hitchcockiana Soreng & P.M. Peterson, 2016

Peterson, Paul M. & Soreng, Robert J., 2016, A revision of Poa subsection Aphanelytrum (Poaceae, Pooideae, Poaeae, Poinae); and a new species, Poa auriculata, PhytoKeys 63, pp. 107-125 : 110-111

Poa hitchcockiana Soreng & P.M. Peterson nom. nov. Figs 1 , 2D , 4C

Brachyelytrum procumbens Hack., Die Nat. Pflanzenfam., Nachträge zu Teil II, Abteilung 2. 42. 1897. Aphanelytrum procumbens (Hack.) Hack., Oesterr. Bot. Z. 52: 13, text f. 1902.

Aphanelytrum decumbens Hack. ex Sodiro, Anales Univ. Centr. Ecuador 3(25): 480. 1889, nom. nud.

Type.

ECUADOR. Crescit in silvis opacis regionis subandinis, 2000 m, Jul 1887, L. Sodiro, s.n. (holotype: W-19813 seen digitally!; isotype: US-865406 fragm. ex W!).

Description.

Straggling and stooling perennials with intravaginal innovations. Culms 30-80 (-100) cm tall, decumbent to erect, delicate, glabrous; nodes 3-8 (-14); internodes 2-14 cm long. Leaf sheaths ½ to 4/5 as long as the internodes, membranous to hyaline, often shiny, upper sheaths open ½ the length, keeled; ligules 1-2 mm long, membranous to hyaline, apex erose, often lacerate; blades 6-14 cm long (flag leaf usually 4-6 cm long), 1.5-4.2 (-5.5) mm wide, flat, thin, lax, linear. Panicles 5-18 (-22) cm long, 2-5 cm wide, few-flowered with 10-22 spikelets, oblong; branches flexuous, effuse and spreading, the lower branches capillary with 2-5 spikelets immediately branching below, the upper branches usually with 2 spikelets. Spikelets 8-18 mm long, 2- or 3-flowered (often appearing 1-flowered with disarticulation of upper florets), laterally compressed, greenish; disarticulation between the florets; all florets usually perfect; rachilla joints 1.5-4.2 mm long, often prolonged above upper floret; glumes 0.1-0.5 (-0.7) mm long, without veins, minute or absent, apex acute or irregularly lobed or toothed; lemmas 5-9.6 mm long, 5-veined, lanceolate, apex acuminate, mucronate or short-awned, the awn up to 2 mm long; paleas 4-7 mm long, 2-keeled, apex bifid; lodicules 0.8-1.1 mm long, lanceolate, membranous, glabrous; stamens 3; anthers 2.8-4.7 mm long, yellowish; ovaries glabrous with two styles and two stigmas. Caryopses 3.25-4.2 mm long, compressed laterally, glabrous, hilum short.

Leaf anatomy.

The transverse section leaf anatomy of Poa hitchcockiana is C3, XyMS+ with non-radiate, spongy chlorenchyma, without adaxial palisade cells. There is a single primary vascular bundle associated with the midrib and a sclerenchyma girder 2 or 3-cells thick on the abaxial surface (Fig. 2D ). Lateral primary vascular bundles are widely spaced and also have a few abaxial sclerenchyma cells.

Phenology.

Flowering year round [?], although no collections made in February, May, and September.

Distribution.

Poa hitchcockiana is found along the paramo or moist jalca vegetation between 2000-4025 m of the Cordillera de los Andes in Colombia, Ecuador, Bolivia, and Peru.

Conservation status.

Since the species is widespread it is of least concern ( IUCN 2010). However, the typical size of populations is undocumented and it has been noted by the authors that the grass is sought after by grazers since it is often found growing among the protection of perennial shrubs.

Etymology.

Since the epithets procumbens and decumbens are blocked in Poa by the earlier Poa procumbens Curtis and Poa decumbens (L.) Scop., we provide a new name commemorating the "father of American agrostology," Albert Spear Hitchcock (1865-1935).

Comments.

The only wide ranging species of Poa subsect. Aphanelytrum , Poa hitchcockiana also has the most unusual spikelet morphology with extremely long rachillas (1.5-4.2 mm long) and very short [0.1-0.5 (-0.7) mm long] to obscure or often absent, unveined glumes. Poa rachillas rarely exceed 1.5 mm, but some have spikelets with rachillas up to 2 mm long (e.g. Poa sect. Secundae V.L. Marsh ex Soreng) Poa curtifolia Scribn., Poa hartzii Gand., Poa stenantha Trin.; ( Poa sect. Cenisiae Asch. & Graebn.) Poa davisii Bor; ( Poa supersect. Homalopoa ) Poa bajaensis Soreng, and a few other species in the Homalopoa (H) clade (see Soreng et al. 2010). Four species of the related genus Nicoraepoa Soreng & L.J. Gillespie have rachillas up to 3 mm long ( Soreng and Gillespie 2007). However, there are no known species of Poa with unveined glumes.

Specimens examined.

Bolivia. El Beni: Bella Vista, 26 Dec 1923, A.S. Hitchcock 22756 (US). La Paz: Murillo, 2450 m, 7 Apr 1981, S.A. Renvoize 4269, T.A. Cope & S.G. Beck (MO); 16°08'S, 68°07'W, 2900 m, 18 Mar 1987, J.C. Solomon 16417 (MO, US); 16°10'S, 68°07'W, 3000 m, 1 Mar 1980, J.C. Solomon 5240 (MO); 3100m, 16 Mar 1982, T. Feuerer 10719B (MO); 7 Apr 1989, Feuerer 5855C (MO). Santa Rosa, 3030 m, 4 Aug 1979, S.G. Beck 1085 (US). Nor Yungus, 3300 m, O. Buchtien 4268 (US); 3250 m, 3 Apr 1981, S.A. Renvoize 4188 & T.A. Cope (K, LPB); Franz Tamayo, 14°43'47"S, 69°04'17"W, 3998 m, 18 Jun 2005, A.F. Fuentes 8338, R. Hurtado, I. Jiménez, E. Cuevas & R. Cuevas (LPB, MO, USZ); Inquisivi, 16°48'00"S, 67°16'00"W, 3400-3500 m, 9 Mar 1991, M. Lewis 38263 (MO). Colombia. Boyacá: Nevado de Cocuy, 3750 m, 10 Sep 1938, J. Cuatrecasas 1360 (US); 4025 m, 7 Oct 1972, A.M. Cleef & P.A. Florschultz 5960 (US). Cauca: 3700 m, 5 Apr 1985, J.R.I. Wood 4784 (MO). Cundinamarca: Bogota, 10 Aug 1859, A. Lindig 1009 (MO, US); Paramo de Chipaque, 3300 m, R. Jaramillo M. 5340 (COL). Meta: Paramo de Sumapaz, 3700 m, A.M. Cleef 7686 (COL). Tolima: 16 Dec 1984, J.R.I. Wood 4650 (MO). Camino del Verjon, 3100 m, Jul 1911, Apollinaire 717 & Arthur (US-727001), Apollinaire 717 & Arthur (US-913275). J. Celestino Mutis 5533 (MA, US). Ecuador. Cañar: Interandina, 3000 m, 2 Jul 1950, M. Acosta Solís 16962 (US). Carchi: 00°49'00"N, 77°57'00"W, 3800 m, 10 Mar 1992, S. Lægaard 101662 (AAU); 00°40'00"N, 77°52'00"W, 3400 m, 1 Nov 1993, W.A. Palacios 11739 (MO, QCNE). Imbabura: 00°20'00"N, 78°00'00"W, 3600-3650 m, 7-8 Feb 1992, S. Lægaard 101171 (AAU). Loja: Cajanuma, 04°05'S, 79°12'W, 2700-3100 m, 5 Mar 1987, I. Grignon 84297 (AAU, MO, US). Napo: 00°56'00"S, 78°23'00"W, 3600 m, 16-18 Nov 1984, S. Lægaard 53356 (AAU, QCA, US). Pichincha: Paso de Huanpango, 3280 m, Jul 1928, G. Firmín 439 (US); Pedregal, 3400 m, 7 Jul 1944, M. Acosta Solís 8333 (US); Montes Pichinchas, 3700 m, 21 Jan 1856, W. Jameson s.n. (US), Jameson 168 (US); Pasochoa near Quito, 1890, L. Sodiro s.n. (US); La Campiña, 3000 m, T. Holmgren 649 (US). Tungurahua: Cordillera de Llanganates, 3000 m, 16 Nov 1939, E. Asplund 9737 (US). Peru. Cusco: Paucartambo, 2800 m, 17 Mar 2002, P.M. Peterson 16571 & N.F. Refulio Rodriguez (US, USM); Calca, 3430 m, 17 Mar 2002, P.M. Peterson 16581 & N.F. Refulio Rodriguez (US, USM); Pillco, 17 Apr 1967, C. Vargas C. 19264 (US); Quispicanche, 13°35'32.8"S, 70°58'39.9"W, 3097 m, 20 Mar 2007, P.M. Peterson 20582, R.J. Soreng & K. Romaschenko (US, USM); Moquegua: El Abra, 2000 m, Mar 1967, C. Vargas C. 19104 (US). San Martín: Huicungo, 7°58'S, 77°20'W, 2900-3150 m, 27 Jun 1999, A. Cano s.n. (SI, USM); B. León 3797 (USM).

Figures

Figure 1. Poa hitchcockiana: A Habit B Panicle C Sheath, ligule, and blade D Spikelet E Lower floret with glumes at base F Glumes at base of lower floret G Lemma H Palea, ventral view I Stamens with ovary J Lodicules at base of ovary K Pistil, lodicules at base L Caryopsis M cross section of caryopsis. A-D, J-K (Peterson 16571 & Refulio Rodriguez) E, F, L, M (Apollinaire 717 & Arthur, US- 913275).

Figure 2. Leaf blade transverse sections of Poa sanchez-vegae (A - C) and Poa hitchcockiana (D). Poa sanchez-vegae: A Entire leaf blade B Midvein showing a single primary vascular bundle with bulliform cells (b indicated by arrows) C Lateral primary vascular bundle with a few associated abaxial sclerenchyma fibers (sf) and spongy chlorenchyma (chl). Poa hitchcockiana: D Midvein showing a single primary vascular bundle with abaxial sclerenchyma fibers (sf) and collapsed chlorenchyma.

Figure 4. Poa sanchez-vegae (A, B, D-L) and Poa hitchcockiana (C). Poa sanchez-vegae: A Habit B Sheath, ligule, and blade D Panicle E Spikelet F Glumes, showing lower 1 - veined and upper 4 - veined G Glumes, showing lower 1 - veined and upper 3 - veined H Lemma I Paleas J Palea, anthers, and rachilla K Lodicules and pistil L Pistil. (Sanchez Vega 11781, Sanchez Montoya, Cueva R. & Montoya, US- 3472470, US- 3686568). Poa hitchcockiana: C Sheath, ligule, and blade (Peterson 16571 & Refulio Rodriguez).