Usually hemiepiphytic, occasionally terrestrial; stem appressed-climbing or scandent; internodes short, semiglossy, 1–13 x 1.5–5 cm, longer than broad, dark green, drying dark reddish brown or dark tan, epidermis coarsely white-ridged becoming brown scurfy ridged and finely transversely fissured, drying longitudinally wrinkled; roots few per node, drying medium brown; cataphylls D-shaped, 6–29 cm, sharply 1- to 2-ribbed, medium green, sometimes red, drying dark reddish brown, persisting intact at base. LEAVES reflexed-spreading to pendent, mostly clustered at apex of stem; petioles 12–49 cm x 1.5– 5 mm (dry), C-shaped in cross section, broadly sulcate at base with one margin sharply acute and the other bluntly rounded, becoming narrowly flattened at apex, dark green, finely striate, drying dark brown; geniculum terete, swollen, 1–2 cm, drying dark and slightly scurfy; blades oblong-elliptic, subcoriaceous, moderately bicolorous, long-acuminate at apex, truncate to obtuse or sometimes slightly cordulate at base, 38–79 x 6–16 cm, 4.5–6.5(–8.9)x longer than wide, 1.4–2.4(–3.1)x longer than petiole, adaxial surface semiglossy to velvety, dark green, drying dull dark reddish brown, abaxial surface semiglossy, paler, drying glossy and paler; midrib convex and paler adaxially, bluntly acute and darker abaxially, drying concolorous or lighter adaxially, darker and raised abaxially; primary lateral veins 19 to 47 per side, 18– 20 mm apart, spreading from midrib at 45º angles near the base becoming more acute distally (to 20º– 25º), down-turned at midrib then curving gradually out to margin, narrowly sunken adaxially, convex and darker than blade abaxially, drying concolorous or paler than blade adaxially, darker than blade and raised abaxially; basal veins 1 to 3 pairs per side, all free to base; interprimary veins often nearly as prominent as primary lateral veins; minor veins obscurely visible. INFLORESCENCE erect, 1 to 5 per axil; peduncle 2.5– 7 cm x 4–6 mm, much shorter than petiole, white to medium green, finely striate, drying dark brown; spathe 16–22 cm, matte to weakly glossy, pale green to greenish white outside, long-tapered, not constricted; spathe blade 7–10 cm, greenish white inside; spathe tube 8–10 cm, glossy, cherry-red to red-violet to magenta inside; spadix cylindrical, 11–15 cm; pistillate portion pale green, cylindrical, 3.3–4 cm long on one side, 5.5–8 cm long on the other side, 7–9 mm diam.; staminate portion cylindrical, pale green, 7–10.2 cm x 7–8 mm; sterile staminate portion not apparent; pistils ca. 1.6x1.6–1.8 mm; ovary 7- to 9-locular, ovules with subbasal placentation, 5 to 8 per locule. INFRUCTESCENCE unknown.
The species is a member of subgenus Philodendron, section Philodendron, subsection Philodendron, series Fibrosa Croat and is characterized by its habit of growth, usually with most of the leaves clustered near the top of the stem, and long pendent leaf blades that have many arching primary lateral veins, markedly sunken adaxially. In addition, the petioles are deeply sulcate with one margin very acute and the other bluntly rounded (hence the epithet from the Greek compound ‘‘hetero’’ for differing and ‘‘craspedon’’ meaning edge or border). The distinctive long-tapered inflorescences are erect and nearly sessile, pale green or white. This species is most easily confused with Philodendron rhodospathiphyllum Croat & D. C. Bay, especially in the dried state. However, P. rhodospathiphyllum differs in having shorter, wider leaf blades held in a spreading or slightly reflexed position and not pendent. It also has primary lateral veins that are farther apart and curve more gradually, and smaller inflorescences that are green outside and inside.