LEAVES spreading-pendent; petioles 11-35 cm long, 5-7 mm diam., ± terete, sometimes flat or weakly sulcate adaxially; geniculum 1.5-2 cm long; blades strap-shaped 32-80 cm long, long-acuminate at apex, acute to rounded at base; upper surface matte to semiglossy, lower surface semiglossy; the midrib acutely raised above, convexly raised below; primary lateral veins numerous, sunken above, raised below; secondary veins distinct; collective vein arising from near the base, 4-5 mm from margin.

INFLORESCENCE spread-ing-pendent, shorter than leaves; petioles 15-45 cm long, 6-7 mm diam.; spathe oblong-lanceolate, yellow-green to purple, usually at least tinged with purple, 10-15 cm long, 2.5-4 cm wide, usually held ± erect; spadix pale violet-purple, 8-12 cm long, 6-9 mm diam. at base, 2-4 mm diam. at apex; the flowers rhombic to 4-lobed, 2.5-2.7 mm long, 2-2.2 mm wide; 4-9 flowers visible in the principal spiral, 6-12 flowers visible in the alternate spiral; tepals matte; pistils green, emergent; stigmas with droplets 2-4 days before stamens emerge; stamens emerging from base, laterals first, preceding alternates by 2-3 spirals, held over pistil in a tight cluster; thecae brown, elliptic; pollen pale orange.

INFRUCTESCENCE with spadix 14-32 cm long; berries orange, ± ovoid, weakly beaked, 11-13 mm long, 6-8 mm wide; seeds 2, pale brown, subovoid, weakly flattened, ca. 6 mm long, 4.5 mm wide, 3 mm thick. Figs. 148 and 149.

The species is found in Costa Rica and Panama from 635 to 2,700 m, principally in premontane rain and lower montane rain forest. Anthurium protensum is a member of section Pachyneurium and is distinguished by its elongate, narrow leaf blades with many primary lateral veins, by its more or less terete petiole, and by its long, ovate to lanceolate spathe, pale violet-purple to lavender or greenish spadix and orange berries. The species is closely related to A. prolatum, A. brenesii, and A. seibertii, all species with similar, elongate leaves. See the commentary following these species for distinguishing characteristics. Anthurium protensum consist of two subspecies. The subspecies protensum occurs only in Costa Rica, while ssp. arcuatum Croat (ined.) occurs in Panama, ranging from Chiriquí to Ve-raguas at 1,300 to 1,750 m in premontane rain forest. The latter differs in being an erect plant with smaller leaves with fewer, more prominent sunken veins, an acute lower midrib, an arching inflorescence with shorter, usually ovate spathe, and a smaller spadix.

Map of Mesoamerican specimens with coordinates

Costa Rica Alajuela: 1300-1450 m, 10.18N 84.47W, 9 June 1985, Michael H. Grayum 5364 (MO).
Costa Rica Cartago: 1250 m, 09.46.30N 83.48.00W, 12 Aug 1984, Michael H. Grayum & Brian Jacobs 3776 (MO).
Costa Rica Cartago: 1700 - 2000 m, 9.44N 83.50W, 24 Sept. 1995, Aguilar, R. et al. 4398 (INB).
Costa Rica Guanacaste: 1550 m, 10.20N 84.48W, 31 January 1989, William Haber 9043 (MO).
Costa Rica Heredia: 1200-1400 m, 10.15.30N 84.05.00W, 13 Nov 1986, Michael Grayum & Gerardo Herrera 7854 (MO).
Costa Rica Lim—n: Canton de Guapiles, 1300 m, 10.06.10N 83.50.45W, 23 Feb 1990, Herrera & Schik 3787 (CR, MO).
Costa Rica Lim—n: 1300 m, 9.24.15N 83.05.15W, 6 Mar. 1992, Herrera 5196 (MO, CR).
Costa Rica Lim—n: 1000 m, 9.24.20N 83.05.35W, 11 Mar. 1992, Herrera 5331 (MO, CR).
Costa Rica Lim—n: Cordillera de Talamanca, 800 m, 09.38.25N 83.08.15W, 28 Feb 1989, Herrera & Solis 2493 (CR, MO).
Costa Rica Puntarenas: Monteverde Reserve, 1500-1550 m, 10.18N 84.48W, 17 July 1992, Ingram & Ferrell-Ingram 1549 (MO).
Costa Rica Puntarenas: 1500 m, 10.20N 84.50W, 24 Dec. 1985, William A. Haber 3897 (MO).
Costa Rica Puntarenas: 1500-1550 m,, 21 Dec. 1984, William A. Haber 1164 (MO).
Costa Rica Puntarenas: Monteverde Reserve, 1500-1550 m, 10.18N 84.48W, 6 Feb 1992, Ingram & Ferrell-Ingram 1264 (MO).
Costa Rica Puntarenas: 1600 m, 10.17N 84.46W, 19 June 1987, William Haber & Erick Bello 7318 (MO).
Costa Rica Puntarenas: 1600 m, 10.17N 84.46W, 19 June 1987, William Haber & Erick Bello 7320 (MO).
Costa Rica Puntarenas: R.B. Monteverde; Cordillera de Tilarán, 1300 m, 10.16N 84.22W, 4 May 1991, Erick Bello, Eladio & Roy Cruz 2726 (CR).
Costa Rica San José: 1600-1800 m, 10.04.00N 84.01.30W, 18 May 1989, Michael Grayum, Rafael Robles & Barry Hammel 9478 (MO).
Costa Rica San José: 2150 m, 9.50.30N 84.06.35W, 6 Nov. 1993, Morales 1969 (MO, CR).
Costa Rica San José: Z.P. Cerros de Escazú; Cerros Escazú-La Carpintera, 1950-2100 m, 09.50.30N 84.07.35W, 17 April 1993, J.F. Morales 1293 (CR).