Epiphytic or hemiepiphytic vine.
Juvenile plants with internodes elongate, more than 10 cm long, the epidermis yellow brown, smooth, moderately glossy, longitudinally folded. Leaves with petiole 18–28 cm long, 1–1.7 cm diam. midway, drying c. 1 cm diam., blackened; blade broadly ovate-sagittate, 22–23 cm long, 18–20 cm wide, 1.1–1.2 × longer than wide, 0.8– 1.2 × as long as petiole, drying dark olive-green; anterior lobe 13–16 cm long, broadly rounded; posterior lobes 8–10 cm long, 6–8 cm wide; sinus narrowly hippocrepiform, 6–7 cm deep, 2.5–3 cm wide; all veins drying concolorous with the blade above, much darker than the blade below; primary lateral veins 2 pairs; basal veins 4–5 pairs, the 3–4 lowest pairs joined for 1–2 cm at the base. Adult plants with stems rooting at the nodes; internodes elongated, 1–6 cm long, 1.5–2.5 cm diam., drying yellow-brown with longitudinal ridges. Leaves erect; petiole subterete, 22–68 cm long, 7–15 mm diam., drying blackened; blade ovate-sagittate, generally widest near the petiole attachment and tapering towards the apex, 44– 67 cm long, 22–37 cm wide, 1.5–2.5 × longer than wide, 1–2.1 × as long as petiole, acuminate at apex, deeply and prominently lobed at base, drying dark olive-green and weakly glossy on both sides; anterior lobe 33–50 cm long, tapering towards the apex; posterior lobes 10–18 cm long, 8–16 cm wide, sometimes curving inwards and overlapping; sinus narrowly triangular, 6–15 cm deep; midrib broad-flattened above, convex below, drying concolorous above, much darker than surface below; primary lateral veins 5–7 pairs, arising at 50–65° angle, flat above, slightly raised below; minor veins fine, moderately distinct; basal veins 4–7 pairs, all free to the base. Inflorescences 4–8 per axil; peduncle 2.5–12 cm long, 1–3 mm diam., drying blackened; spathe greenish white or creamy white at anthesis, drying blackened, 5.8–7 cm long, 1–1.3 cm diam., broadest toward apex on the blade portion, flattening to 2.8–3.2 cm wide, the tube 6–9 mm diam.; spadix 5.5–6.2 cm long, greenish; staminate portion 3–3.5 cm long, 7 mm diam., pistillate portion 2.7–3.7 cm long, 5 mm diam.; pistils 4–5 locular, 1.5 mm long, 0.8–1 mm diam., subrounded to pentagonal from the apex; ovules 2–3 per locule, basal, 0.2 mm long (including the funicle), the funicle about as long as the ovule; the entire spadix drying blackened.
Philodendron urraoense is a member of P. sect. Philodendron sect. Macrobelium subsect. Macrobelium and is characterised by its hemiepiphytic climbing habit, the internodes usually longer than broad and drying yellow-brown with longitudinal ridges, petioles subterete and shorter than blades and drying blackened, blades ovatecordate and drying somewhat blackened with a narrow, triangular sinus and with the basal veins free to the base or nearly so as well as by the cluster of up to 8 moderately small greenish white, long-pedunculate inflorescences.