Epiphytic or hemiepiphytic vine; internodes short or elongate, 5-17 cm long, 3.0 cm diam., medium green, glossy, with short white streaks at apex of new node (white striate at apex), becoming promptly gray-green, gray-brown to brown and semiglossy; cataphylls green, sometimes reddish or tinged red, dashed with white streaks, unribbed, deciduous or persisting intact at upper nodes; petioles 48-75 cm long (averaging 63 cm), 4-7 mm diam. at middle, erect-spreading, terete, moderately firm, medium green, faintly whitish striped (striate), semiglossy; blades ovate, acute to weakly acuminate at apex, cordate at base, 33-51 cm long, 23-36 cm wide (averaging 28.7 X 45.8 X cm), 1.2-1.8 times longer than broad, 0.6--0.9 times length of the petioles, convex at margins; surfaces semi-glossy to glossy, somewhat to moderately bicolorous, subcoriaceous; anterior lobe 25-43 cm long; posterior lobes 9-16 cm long, 8-15 cm wide, directed slightly inward, sometimes somewhat unequal on the two sides; sinus narrowly parabolic to spathulate, 7-11 cm deep, 4-7 wide; midrib obtusely I-ribbed or convex, and much paler above, narrowly rounded to convex and slightly paler below; basal veins 6-9 pairs, more or less free to base, quilted-sunken above, convex and slightly paler below; primary lateral veins 17-21 per side, departing midrib at 60°-90° angles, ascending to margin, narrowly quilted sunken above, convex and slightly paler below; minor veins few, moderately visible to moderately obscure. INFLORESCENCES erect to spreading, 4 per axil; peduncle 6-7 cm long, 2-3 mm diam. at middle, medium green to greenish white, conspicuously pale striate, elongating to 11.5 cm long, flattening to 1.1 cm wide in fruit; spathe medium green to greenish white, paler toward apex, and conspicuously striate outside, dark maroon within with whitish lines, heavily tinged toward the apex, except at the tip, 11.2-14 cm long, flattened to 2.5 cm wide; tube 5-6 cm long, 1.5-2 cm diam.; blade 1-1.6 cm wide; spadix 10-13 cm long; pistillate portion pale green, 3.2-4.8 cm long on front, 2.1-4.0 cm long on back, 9-11 mm diam.; staminate portion 5.5-6.5 cm long, 6-8 mm diam.; sterile staminate portion 1.1-1.4 cm long, 0.9-1.2 mm diam.; staminate flowers 1.6-2.3 mm long, 1.2-1.7 mm wide; sterile staminate flowers 1.5-1.8 mm long, 1.1-1.3 mm wide; pistils 2.4-3.0 mm long, 1.2-2.1 mm diam.; locules 5-6 per ovary; ovules 1 per locule, 0.8-1.0 mm long, 0.3-0.4 mm wide. INFRUCTESCENCES to 16 cm long, 3 cm diam.; seeds 1.2 mm long, 0.6--0.8 mm diam., dark yellow-brown, minutely granular, semiglossy, with a broad nipple at one end.
Philodendron planadense is known from the type locality near La Planada (hence the name P. planadense), Colombia (Narino), and also adjacent Ecuador (Carchi), at elevations of 1,750-2,265 m, in Premontane wet forest life zone. Apparently uncommon at La Planada, this species was collected in the regrowth forest along the trail above La Posada and in the swampy old pasture area south of the Sendero Natural, as well as in other sites not specifically described.