Plant epiphytic, sub-twining. Stem thick. LEAVES crowded, petiole thick, conspicuously sulcate, up to 45 cm long, 13 mm in diameter. Blade strongly coriaceous, very glossy on upper surface, pale green below, lanceolate-elliptic, base conspicuously cordate, apex shortly acuminate; midrib thick, striate in a dried state, more or less 1 cm in diameter at base, primary lateral veins usually equal, parallel, very numerous emerging at a ca. obtuse angle from the midrib, moderately broad at the base, becoming faint upwards, ascending somewhat arcuately towards the margin. INFLORESCENCE: Peduncle subequal to the spathe, terete, but thickened towards the apex, green, more or less 12 cm long, 5-6 mm in diameter. Spathe green externally, more or less 14 cm long. Spadix stipitate (1 cm), subequal to the spathe up to 12 cm long; Female zone 4.5 cm long, thickened basally, 1.7 cm in diameter; male zone 5-5.5 cm long, more or less 6 mm in diameter, sterile male zone 1-1.4 cm long. Pistil broadly columnar, apex strongly truncate, not angular, more or less 3 mm long, 1.5 mm in diameter, stigma subcircular, pilose, with a fleshy crown. Male flowers diandrous, Staminodes truncate, irregularly elongate-rhombic, usually 0.5 mm long, 0.3-0.8 mm wide; stamens not as strongly unequal as staminodes, apex strongly truncate, 0.5 mm long, ca. ('in circuitu') square, 0.5x0.5 mm in diameter, anthers more or less 0.4 mm long.
The leaves and petioles of Philodendron craspedodromum are reputed by the Desano Indians of the Rio Papuri to be toxic to fish when crushed and cast into stagnant waters. When used for fish-poisoning, the leaves are cut, tied into small bundles and set on the forest floor for one or two days to "steam" and start fermentation and rotting before being crushed for use.