Anthurium lactiflorum Engl., Bot. Jahrb. Syst. 6: 277. 1885. TYPE: Colombia, Lehmann 2582 (B).

Epiphytic or often terrestrial; stems often to 1 m long; roots thick, directed downward; cataphylls coriaceous, narrowly rounded at apex, with subapical apiculum, drying tan, persisting intact.

LEAVES erect-spreading; petioles 40-150 cm long, 0.6-1 cm diam., subterete, weakly flattened or weakly sulcate adaxially; geniculum 2-2.2 cm long, tinged pinkish; blades ovate, 30-80 cm long, 20-52 cm wide, acuminate and turning down at apex, deeply lobed at base; anterior lobe 31-54 cm long; the posterior lobes 13-20 cm long; sinus broadly hippocrepiform to spathulate; both surfaces glossy; midrib acutely raised above and below; primary lateral veins 7-9 per side, sunken in valleys above, raised below; interprimary veins sunken above, raised below; basal veins 7-8 pairs, the fourth to sixth coalesced 2.5-3 cm; the posterior rib naked, turned up; collective vein usually arising from one of the lowermost basal veins, frequently from the second or third basal vein, 2-4 mm from the margin.

INFLORESCENCE erect-spreading; peduncle 21-47 cm long, stout; spathe subcoriaceous, ovate or oblong-elliptic, pale greenish white to pale violet, 12.5-24 cm long, 3-8.5 cm wide, cuspidate at apex, round at base, held close to spadix even in fruit, inserted at 45° angle on peduncle; spadix stipitatc 12-15 mm in front, 2-3 mm in back, white to violet-purple, ± oblong to tapered to both ends, 5.5-14.5 cm long, 1.2-1.5 cm diam. at middle, 7-9 mm at base and apex; flowers rhombic to 4-lobed, 2.3-3 mm long, 3-3.8 mm wide, the sides jaggedly sigmoid; 9-15 flowers visible in the principal spiral, 10-20 flowers visible in the alternate spiral; tepals glossy, the lateral tepals 1-1.5 mm wide, the inner margins rounded to an-gulate; pistils early emergent; stigmas deep purple, ultimately brushlike; stamens emerging from base of spadix, the lateral stamens emerging throughout before alternate stamens emerge, held in a tight cluster over pistil; filaments pale lavender; anthers pale lavender to deep red-violet, sometimes white tinged with red-violet at margins; pollen white.

INFRUCTESCENCE with spadix 18-32 cm long; berries dark reddish-violet to violet-purple, often reddish-orange at base, narrowly acute at apex, 10-12 mm long, 4-5 mm wide; seeds 2, 7-8.4 mm long, 3-3.5 mm wide. Figs. 76 and 79.

The species is found in Costa Rica, Panama, Colombia, and perhaps also Ecuador [see Gentry 9621 (MO)] at elevations of 500 to 1,500 m. In Costa Rica and Panama the species occurs in premontane wet forest and more commonly in premontane rain forest and lower montane rain forest. It is often one of the most common species at middle elevations, where it is generally found along shady road banks and sometimes forms large stands. Anthurium formosum is variable both in size of leaves and inflorescences and in the color of the spathe and spadix, both of which vary from white to purplish-violet at anthesis. The spathe and spadix, if white at anthesis, tend to become more colored with age. The collective vein is also quite variable, sometimes arising from one of the lowermost basal veins or sometimes from the second or third basal vein. The species is a member of section Calomystrium and is distinguished by its usually large cordate blade with a prominent posterior rib, by its large ovate or oblong-elliptic, subcoriaceous spathe, glossy tepals, sharp, early-emergent pistils and reddish-violet to violet-purple berries. Leaf blades usually dry olive green with characteristic reddish-brown veins and with purplish and/or brownish blotches.
 
 

Map of Mesoamerican specimens with coordinates

Costa Rica Cartago: Valle del Reventazón, 1200 m, 09.49.50N 83.26.40W, 16 September 1992, Priscila Campos & M.M. Chavarría 24 (CR).
Costa Rica Cartago: 1130 m, 09.40N 83.48W, 7 September 1996, Thomas B. Croat 79071 (MO).
Costa Rica Heredia: P.N. Braulio Carrillo, 1150 m,, 23 Jan 1983, Garwood et al. 462 (BM).
Costa Rica Heredia: 700-750 m, 10.17.30N 84.04.30W, 4 April 1986, Michael H. Grayum 6764 (MO).
Costa Rica Heredia: Finca La Selva, 100 m,, , Jacobs 2350 (DUKE).
Costa Rica Heredia: Finca La Selva, 100 m,, , Jacobs 2338 (DUKE).
Costa Rica Heredia:, 03 Aug. 1979, Grayum & Sperry 2218 (MO).
Costa Rica Lim—n: 1450 m, 9.47.20N 83.08.18W, 28 April 1989, Gerardo Herrera & Abelardo Chacón 2845 (MO).
Costa Rica Lim—n: 150 m, 9.29.50N 82.59.10W, 30 June 1989, Gerardo Herrera 3093 (MO).
Costa Rica Lim—n: 5 m, 10.40.30N 83.39.30W, 19 Sep 1986, Gerrit Davidse & Gerardo Herrera 31460 (MO).
Costa Rica Lim—n: 300 m, 9.25.10N 83.03.00W, 25 February 1992, Reinaldo Aguilar H. Schmidt 982 (MO).
Costa Rica San José: 500 m, 10.09N 85.57W, 17 May 1988, María M. Chavarría & G. Umaña 156 (MO).
Costa Rica San José: 10.10N 84.00W, 5 June 1986, Greg de Nevers & Barry Hammel 7826 (MO).
Nicaragua Río San Juan: 5m m,, 01 Dec. 1982, Araquistain, M. 3366 (MO).
Nicaragua Río San Juan: Río Indio, <20 m, 11.07.00N 083.50.00W, 08 Sept. 1982, Riviere 290 (MO).
Panama Bocas del Toro: 700 m, 8.45N 82.15W, 10 March 1985, T.B. Croat & M.H. Grayum 60246 (MO).
Panama Bocas del Toro: 1200 m, 8.44N 82.17W, 11 March 198, T.B. Croat & M.H. Grayum 60320 (MO).
Panama Bocas del Toro: 175 m, 8.46N 82.16W, 25 June 1987, Thomas B. Croat 66823 (MO).
Panama Bocas del Toro: 120 m, 8.55N 82.10W, 5 March 1986, Gordon McPherson 8552 (MO).
Panama Bocas del Toro: 1000 m, 8.45N 82.15W, 7 Dec 1985, Gordon McPherson 7828 (MO).
Panama Bocas del Toro: 1700 m, 8.35N 81.45W, 15 April 1986, Gordon McPherson 8921 (MO).
Panama Chiriquí: 1200 m, 8.41N 82.13W, 17 Mar. 1985, Hampshire & Whitefoord 721 (BM).
Panama Chiriquí: 1100-1135 m, 8.43N 82.17W, 8 March 1985, T.B. Croat & M.H. Grayum 60005 (MO).
Panama Chiriquí: 1200-1300 m, 8.45N 82.18W, 22 June 1987, Thomas B. Croat 66622 (MO).
Panama Chiriquí: 8.46N 82.16W, 23 Sept. 1987, Thomas B. Croat 68029 (MO).
Panama Chiriquí: 1100-1300 m, 8.45N 82.15W, 26 Apr. 1988, Thompson 5002 (CM,MO).
Panama Chiriquí: 1150 m, 8.45N 82.15W, 23 Oct. 1985, Gordon McPherson 7278 (MO).
Panama Chiriquí: 1100 m, 8.45N 82.13W, 8 Feb. 1984, H.W. Churchill, G. de Nevers & H. Stockwell 4915 (MO).
Panama Chiriquí: 1100 m, 8.45N 82.14W, 18 Sept. 1984, H.W. Churchill & A. Churchill 6080 (MO).
Panama Chiriquí: 1100 m, 8.45N 82.13W, 8 Feb. 1984, H.W. Churchill, G. de Nevers & H. Stockwell 4812 (MO).
Panama Chiriquí: 1100-1400 m,, 31 July 1984, W.G. D'Arcy, H.W. Churchill & C. Todzia 15906 (MO).
Panama Chiriquí:, 7 December 1997, D.W. Roubik & L. Quroz 1278 .
Panama Chiriquí:, 16 April 1997, D.W. Roubik, E. Samudio & Quiroz 795 .
Panama Chiriquí:, 7 December 1997, D.W. Roubik & L. Quroz 1280 .
Panama CoclŽ: 680-770 m, 08.39N 80.36W, 25 March 1993, Thomas B. Croat 74830 (MO).
Panama CoclŽ: 680-770 m, 08.39N 80.36W, 25 March 1993, Thomas B. Croat 74850 (MO).
Panama CoclŽ: 89.39N 80.36W, 23 June 1988, Thomas B. Croat 68844 (CM,MO).
Panama CoclŽ: 1000-1100 m, 8.37N 80.7W, 24 February 1988, Gordon McPherson 12152 (MO).
Panama Darien: Río Cocalito,, 19 Feb. 1982, Whitefoord & Eddy 250 (BM).
Panama Panamá: 700-750 m, 9.15N 79.25W, 19 June 1988, Thomas B. Croat 68659 (MO).
Panama Panamá: Río Pacora, 840 m,, , Herrera 2327 (GH).
Panama Panamá: 600-800 m, 9.17N 79.17W, 20-25 Apr 1985, B. Hammel & G. deNevers 13612 (MO).
Panama Veraguas: 1100-1400 m, 8.35N 81.05W, 15 July 1983, C. Hamilton & K. Krager 3977 (MO).
Panama Veraguas: 570 m, 08.33N 81.08W, 13 July 1994, Thomas B. Croat & Guanghua Zhu 76800 (CM, MO).