Epiphytic; stems thick, short, 3-6 cm diam.; cataphylls drying tan, splitting at base, the apex remaining more or less intact; petioles 10-55 cm long, 6-10 mm wide, more or less quadrangular, 5-ribbed; blades strap-shaped, obtuse to slightly rounded at base (20-)45-85 cm long, 4-16 cm wide. Inflorescence erect or spreading; peduncle (15-)30-60 cm long, (4-)6-10 mm diam., terete with a single dorsal rib, sometimes tinged purplish; spathe medium thick, green or green tinged with purple, oblong-lanceolate, rarely narrowly ovate, (6-)10-17 cm long, (2.3-)2.5-4.3 cm wide; spadix purple, (6-) 10-20 cm long, (6-)7-13 mm diam. at base; berries orange, obovoid, flat to rounded at apex, 10-12 mm long; seeds 2. See Croat (1983: 381) for a more complete description.

Anthurium seibertii is known from higher elevations in Chiriquí Province (1,300 to 2,000 m) and from two collections from Costa Rica, one made at 1,040 m in San José Province [Skutch 2626 (MO, US)] and a second from Lim—n Province in Valle de Silencio at approximately 2,000 m [António 1675 (MO)].

The species is a member of section Pachyneurium and is very similar to Anthurium protensum. They share similar strap-shaped leaves, purple spadices, and orange berries. Anthurium protensum differs in having a nearly terete petiole, while A. seiberlii has petioles that are rectangular and prominently ribbed abaxially. Anthurium protensum also has leaves that are usually pendent and generally smaller than those of A. seibertii.

Map of Mesoamerican specimens with coordinates

Costa Rica Alajuela: 1375 m,, 16 Jan 1939, Smith 1498 (NY).
Costa Rica Lim—n: Valle de Silencio, 6000-6500 ft,, 9 Aug 1979, António 1675 (MO).
Costa Rica Puntarenas: 1700 m, 9.17N 83.13W, 24 September 1989, Abelardo Chacón 408 (MO).
Costa Rica Puntarenas: 1700 m, 9.17N 83.13W, 24 September 1989, Abelardo Chacón 409 (CR, MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 1500-1600 m, 09.02N 82.59W, 6 Sep 1984, Davidse et al. 28395 (MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 2000-2500 m, 09.03-6N 82.58-59W, 7 Sep 1984, Davidse et al. 28565 (CR, MO).
Costa Rica Puntarenas: Río Baru, 201 m,, 19 Aug 1983, Gomez et al. 21523 (MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 1800-2200 m, 09.49-57N 82.46-49W, 11 March 1984, Davidse et al. 25535 (MO).
Costa Rica Puntarenas: Canton de Coto Brus, 1200 m, 08.49N 82.58W, 6-7 March 1984, Croat 57259 (MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 1800-1850 m, 09.7N 83.4W, 20 March 1984, Davidse et al. 25613 (CR, K, MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 1800-1850 m, 09.7N 83.4W, 20 March 1984, Davidse et al. 25602 (K, MO, RSA).
Costa Rica Puntarenas: Río Cotoncito,, , Chacon et al. 1768 (DUKE, MO, RSA).
Costa Rica Puntarenas: Cordillera de Talamanca, 1800-1900 m, 08.59N 82.46W, 3 Sep 1983, G. Davidse 24528 (MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 1800-1900 m, 08.59N 82.46W, 3 Sep 1983, G. Davidse 24534 (MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 2000-2300 m, 09.00N 82.49W, 20 Aug 1983, Davidse et al. 23789 (MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 2300 m, 09.7-10N 83.4-00W, 28 March 1984, Davidse & Herrera 26179 (CR, MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 2300 m, 09.7-10N 83.4-00W, 28 March 1984, Davidse & Herrera 26183 (CR, MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 1800-1850 m, 09.7-10N 83.4-00W, 20 March 1984, Davidse et al. 25636 (B, MO).
Costa Rica Puntarenas: Río Baru, 2010 m,, 19 Aug 1983, Gomez et al. 21800 (CR, MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 2000-2300 m, 09.00N 82.49W, 20 Aug 1983, Davidse et al. 23791 (MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 2000-2300 m, 09.00N 82.49W, 20 Aug 1983, Davidse et al. 23790 (MO).
Costa Rica Puntarenas: Cordillera de Talamanca, 2000-2300 m, 09.00N 82.49W, 20 Aug 1983, Davidse et al. 23831 (MO).
Costa Rica Puntarenas: Monteverde Reserve, 11.20N 84.40W, 2 Sep 1981, Hepper 110 (BM).
Costa Rica Puntarenas: R.I. Ujarrás; Cordillera de Talamanca, 2200-2600 m, 09.21.10N 83.16.38W, 6 October 1989, Marlon Valerio 196 (CR).
Costa Rica San José: 1900 m,, 5 Sept. 1975, Utley & Utley 3059 (MO).
Costa Rica San José: 1040 m,, Feb. 1936, Skutch 2626 (F, MO).
Costa Rica San José: 1715 m, 09.28.34N 083.40W, 9 July 1992, Kress, W. et al. 92-3470 (INB).
Panama Chiriquí: Quebrada Velo, 5000 ft.,, 24 July 1947, Allen 4682 (G).
Panama Chiriquí: Boquete Region, 5500 ft,, 12 May 1971, Proctor 31816 (LL).
Panama Chiriquí: 08.50N 82.44W, 28 February 1985, Henk van der Werff & J. Herrera 7303 (MO, RSA).
Panama Chiriquí: Dtto. Bugaba, 1300 m, 08.50N 82.44W, 26 February 1985, Henk van der Werff & J. Herrera 7126 (B, MO).
Panama Chiriquí: Cerro Punta Region, 1800-2200 m, 8.53N 82.37W, 13 July 1983, C. Hamilton & K. Krager 3894 (B, K, MO).
Panama Chiriquí: Cerro Punta Region, 200 m,, 23 June 1970, Luteyn 902 (MO).
Panama Chiriquí:, 30 May 1979, Thomas B. Croat 10555 (MO).
Panama Chiriquí: Río Chiriquí Viejo, 1500-2000 m,, 16 Jan. 1939, Allen 1506 (MO).
Panama Chiriquí: Boquete Region, 1500 m,, 18 July 1940, Woodson & Schery 599 (MO).
Panama Chiriquí: Cerro Horqueta, 1500-1830 m,, 20 July 1968, Dwyer 8749 (MO, DUKE).
Panama Chiriquí: Cerro Punta Region, 2000-2170 m,, 7 May 1978, Hammel 2994 (MO).
Panama Chiriquí: Cerro Punta Region,, 24 Apr. 1969, Lazor 2727 (MO).
Panama Chiriquí: Cerro Punta Region, 2470 m,, 9 Apr 1979, D'Arcy et al. 13196 (MO).
Panama Chiriquí: 3000 m,, 8 Apr. 1979, Hammel et al. 6916 (MO).
Panama Chiriquí: Cerro Horqueta, 1870-2470 m,, 19 march 1979, Averett et al. 1084 (MO).
Panama Chiriquí: Río Caldera, 2130 m,, 20 March 1979, D'Arcy et al. 12761 (MO).
Panama Chiriquí: Cerro Punta, 2000-2330 m,, 22 Oct. 1977, Folsom 6035 (MO).
Panama Chiriquí: Boquete Region, 1670 m,, 23 July 1959, Stern et al. 1076 (MO).
Panama Chiriquí: Cerro Punta Region, 1500-2000 m,, 1938, Woodson et al. 882 (MO).
Panama Chiriquí: Cerro Punta Region,, 30 May 1970, Thomas B. Croat 10551 (MO).
Panama Chiriquí: Boquete Region,, 20 July 1971, Thomas B. Croat 15844 (MO).
Panama Chiriquí: Cerro Punta Region, 2000 m,, 7 Aug. 1974, Thomas B. Croat 26427 (MO, SEL).
Panama Chiriquí: Cerro Punta Region, 2000 m,, 7 Aug. 1974, Thomas B. Croat 26494 (B, CM, CAS, DUKE, K, MO).
Panama Chiriquí: Cerro Punta Region,, 20 Feb. 1971, Thomas B. Croat 13618 (MO).
Panama Chiriquí:, 22 July 1971, Croat & Porter 16063 (M, MO, RSA, U, VEN).
Panama Chiriquí: Cerro Horqueta, 1650 m,, 13 Aug. 1974, Thomas B. Croat 26976 (B, CM, CR, F, GH, K, M, MO, NY, PMA, RSA, US).
Panama Chiriquí: Cerro Pate Macho, 1700-2100 m, 8.47N 82.22W, 24 Apr. 1982, Knapp & Schmalzel 4794 (MO, USM).
Panama Chiriquí: 2250-2400 m, 8.50N 82.32W, 9 Nov. 1980, Stevens 18226 (MO, PMA).
Panama Chiriquí: Cerro Punta Region, 1600 m,, 23 Feb. 1974, Nee 9945 (MO).
Panama Chiriquí: Boquete Region,, 21 July 1971, Thomas B. Croat 15743 (MO, NY).
Panama Chiriquí:, 5 June 1979, António 1059 (MO).
Panama Chiriquí: Dtto. Boqute,, 17 Jan 1938, Davidson 225 (MO).
Panama Chiriquí: Dtto. Boqute,, 9 Feb 1938, Davidson 276 (MO).
Panama Chiriquí: Río Chiriquí Viejo, 1300-1900 m,, 1935, Seibert 289 (MO).
Panama Chiriquí: Cerro Horqueta, 1670-1930 m,, 13 Dec. 1966, Burch 553 (MO).
Panama Chiriquí: Cerro Punta, 2000 m,, 25 Nov. 1979, Thomas B. Croat 48568 (K, MO, PMA, SEL).
Panama Chiriquí: Boquete Region, 1800 m,, 8 July 1940, Woodson & Schery 265 (MO).
Panama Chiriquí:, 17 Nov. 1978, Hammel 5667 (MO).
Panama Chiriquí: Cerro La Trompeta, 2070 m,, 25 May 1979, Hammel 7464 (MO).
Panama Chiriquí: Boquete Region, 1500-2500 m,, 21 March 1977, D'Arcy 10853 (MO).
Panama Chiriquí: Boquete Region,, 20 March 1977, Folsom 2194 (MO).
Panama Chiriquí: Cerro Horqueta, 1660-1700 m, 8.49N 82.29W, 1 Jan. 1975, Cochrane et al. 6243 (MO, WIS).
Panama Chiriquí: Cerro Punta Region, 2330 m,, 2 Apr. 1979, Hammel et al. 6623 (MO).
Panama Chiriquí: Cerro Punta Region, 1500-2000 m,, 1938, Woodson et al. 982 (MO).
Panama Chiriquí: Cerro Punta, 2000-2330 m,, 22 Oct. 1977, Folsom 6034 (MO).
Panama Chiriquí: 1730 m, 8.49N 82.28W, 19 February 1986, Scott Hoover 1340 (MO).
Panama Chiriquí: 1630-1780 m, 8.46N 82.25W, 18 June 1987, Croat 66358 (MO).
Panama Chiriquí: 2200 m,, , Correa & Lazor 1407 (PMA). Panama Chiriquí: 1700 m,, , McDaniel 10161 (IBE).
Panama Chiriquí: Cerro Pate Macho, 1500-1700 m, 8.50N 82.25W, 6 January 1983, Bruce A. Stein Bob Schmalzel and David W. Roubik 1183 (MO).