Climbing, sprawling terrestrial or epiphytic plant; internodes elongated, 2.5–5 cm diam., the epidermis light brown, cracking transversely and exfoliating; cataphylls to 28 cm long, drying dark brown, deciduous. Leaves large; petiole whitish striate, convex below, more shallowly convex above, margins rounded, 38–52 cm long, 1.1–1.3 cm diam. at base, 7–8 mm diam. at apex, sheathing to c. 11 cm; blade ovate-sagittate, widest just above the petiole attachment, 38–51 cm long, 32–38 cm wide, 1.2–1.35 × longer than wide, 0.9–1.3 × as long as petiole, gradually acuminate at apex, conspicuously lobed at base, subcoriaceous, virtually concolorous, glossy on both sides, drying light brown; anterior lobe 27–40 cm long, broadly convex along the margins; posterior lobes 14–20 cm long, 11–14 cm wide, rounded at apex and extending inward; sinus hippocrepiform to spathulate, 9–13 cm deep, 3–10 cm wide; midrib flattish above and paler than the blade, convex below; primary lateral veins 14–18 pairs, arising at 50–70° angle, sunken above and C-shaped below, drying concolorous with the blade above, dark brown below; basal veins 9–13 pairs, the first 1–3 pairs free to the base, the remaining fused to various extent and branching from the posterior rib; posterior rib thick, free for 2–3 cm and then extending for a short distance into the posterior lobes before splitting into individual basal veins; minor veins visible below, darker, forming a network of closely parallel veins between the primary lateral veins. Inflorescences 1–4 per axil; peduncle terete, (4–)8–15 cm long, 2–3 mm diam., finely whitish striate, drying medium brown; spathe (5–)6–9 cm long, with tube about half the length of the spathe, 6–8 mm diam., blade slightly open, 8–10 mm diam., spathe white, yellow- green, light green with reddish apex or magenta (on both surfaces as described by Grayum & al. 7632); spadix 9.5–10.3 cm long, white, cream, green with reddish tip, sometimes with staminate portion yellow-orange; pistillate portion 5.3–5.5 mm diam. at base and at apex, 6.5 mm diam. midway; staminate portion 4.8–5.3 cm long, sterile staminate portion 4.6 mm long, 4.5 mm diam., scarcely distinguishable from the fertile staminate flowers; pistils 1.1–1.3 mm, 1.2–1.6 mm diam., stigmas 0.6 mm diam., 0.1–0.2 mm thick; locules 6–7 per ovary, ovules 1–2 per locule, 0.13 mm long, the funicle affixed at one side of the base, c. 0.5 mm long; placentation basal.
The species is a member of Philodendron subg. Philodendron sect. Macrobelium subsect. Oligocarpidium characterised by its climbing and sprawling, generally epiphytic habit, its broad ovate-sagittate leaves 1.2–1.35 × longer than wide and widest just above the petiole attachment, its numerous (14–18 pairs) primary lateral veins, its 9–13 pairs of basal veins forming a relatively short posterior rib, and its 1–4 small inflorescences per axil.
Philodendron pipolyi somewhat resembles P. clewellii Croat, a Panamanian species, which also has small inflorescences, but that species only has 4–6 widely spaced primary lateral veins instead of the 14–18 pairs found in P. pipolyi; it also has much fewer basal veins (3–4 pairs instead of 9–13 pairs for P. pipolyi). In addition, P. clewelii has the stem epidermis deeply folded longitudinally but otherwise not transverse-fissured.