Slender, monoecious, widely spreading climber, growing into canopy but usually lower than 8 m; trunk 3-5 cm diam; juveniles usually erect. Leaves usually ca 2 m long; petioles short; rachis with black, flattened spines, often recurved, their bases swollen; base of petiole and sheath with denser, shorter spines, the leaf sheaths extending 3-12 cm above petiole; leaflets alternate, long-lanceolate, acuminate, 12-27 cm long, 2.5-4 cm wide, broad at middle, the margins unarmed, the surfaces glabrous or puberulent, the upper surface sometimes with weakly elevated cross-lines, the midrib pronounced but the side veins indistinct, the underside often with 1 or more acicular spines; pinnae becoming opposite toward apex of blade, finally replaced by large, opposite, stout, reflexed spines. Spathes to ca 24 cm long, the rachillae 15 or more, slender (less than 2 mm wide), flexuose in fruit, the peduncle and lower part of rachis armed with short prickles (sometimes with pustular bases); flowers either in triads with 1 pistillate between 2 staminate or with staminate flowers solitary near end of rachilla; staminate flowers soon deciduous, ca 8 mm long; calyx short, tridentate; petals 3, ovate, oblique, acuminate, fleshy; stamens usually 8 or 9; filaments fused to petals at base; pistillate flowers with a small annular calyx; corollas much longer than calyx, urceolate, tridentate, with very small, adnate staminodia; pistils ovoid, 3-celled; styles short; stigma trifid. Fruits bright red at maturity, ellipsoid, 1.5-2 cm long, glabrous; exocarp thin; mesocarp fleshy; seed 1, ca twice as long as broad, obscurely 3-sided with a pore on each side and with dark lines radiating from each pore; cupule inconspicuous. Croat 7759, 11288. Fruits are eaten by white-faced monkeys from April to August (Hladik & Hladik,1969). The species is similar to and perhaps inseparable from D. orthacanthos Mart. of South America, which was described as a plant forming dense thickets in clearings, with a spathe more than 50 cm long, whereas D. isthmius is always in forests and has a much shorter spathe. In addition, the type illustration by Martius (1824) showed the recurved spines to have long filiform appendages. Probably the Panamanian plants will not be found to be distinct from other Central American plants from Mexico south, which are now known as D. chinanthlensis Liebm.