Terrestrial, to 90 cm tall; internodes short, 1.5-2 cm diam.; cataphylls ca. 10 cm long, unribbed, drying thin, reddish brown, soon weathering to pale fibers. LEAVES: Petioles 62-63 cm long, drying 4-7 cm wide, light reddish brown, matte, densely and conspicuously warty-verrucose-scaly throughout, especially near the apex, the scales stalked, especially toward apex, blunt and knob-like at apex, sometimes with as many as 3 knobby excressences per stalk, the glands becoming sparce toward the base and shorter, merely warty, non-stalked excrescences; geniculum ca. 2 cm long, not conspicuously different that the petiole on dried material; blade broadly ovate-cordate, 36-40 × 32-33 cm, 1.5-1.7 times longer than wide, more or less rounded and weakly acuminate at apex, deeply cordate at base, drying weakly glossy, gray-green above, grayish yellow-brown and weakly glossy below; anterior lobe 24-28 cm long, broadest about 6 cm above petiole attachment; sinus spathulate (closed or nearly so), 11.5- 13 cm deep, 2.6-2.8 cm wide when flattened; posterior lobes 14-16 × 12-15 cm; basal veins 5-6 pairs, the first 1st and 2nd free to the base, the 1st pair turned down prominently along sharply along the midrib, the 3rd and higher order veins closely contiguous and almost fused for 1-1.5 cm, some of the basal veins branched about midway; midrib drying broadly convex, finely ribbed above, bluntly acute, finely ribbed below; primary lateral veins 3 per side, arising at an acute angle then spreading at 55-60° angle, flat and concolorous above, narrowly raised and reddish brown, darker than surface below; minor veins drying prominently undulate on both surfaces. INFLORESCENCE with peduncle 7.5-12 cm long, drying 4-5 mm wide, medium reddish brown, bluntly striate; spathe white, drying reddish brown, 14.5 cm long, prominently constricted above the tube; tube 7 × 3 cm; pistils 2.5 × 1 mm; ovary 5-locular, the side densely purplish short-lineatepunctate; locules with ca. 20 ovules, with axile placentation; seeds 7-9 × 3-4 mm, coarsely longitudinally 8-12 ribbed around the sides.
The species is recognized by terrestrial habit, creeping stems, persistent cataphyll fibers, densely warty-verrucose-scaly petioles, and ovate-cordate blades. Philodendron swartiae is related to other members in an unnamed section and species in the group include P. pastazanum K. Krause and P. gloriosum André. Philodendron pastazanum differs in having a peltate blade. Philodendron gloriosum, a species endemic to Colombia, differs in having the major veinsprominently paler than the surface.