Hemiepiphytic; stem appressed-climbing; internodes short, densely covered with cataphyll fibers, 0.5–3 x 1–3.5 cm, thicker than broad, pale green, drying medium tan with longitudinal wrinkles; roots several per node, reddish brown, drying medium brown; cataphylls to 20 cm, unribbed, rounded at apex, soft, medium green, drying as pale fibers with reddish brown epidermis, persisting intact at upper nodes, then weathering to pale fibers. LEAVES clustered near apex of stem, spreading to reflexed-spreading; petioles 14–46 cm x 4–8 mm (dry), thicker than broad, sharply and narrowly sulcate adaxially with a faint medial rib, narrowly rounded abaxially, olive-green, firm, drying dark olive-green; geniculum swollen, 5–15 mm, darker in color, drying darker and sometimes wrinkled; blades oblong-elliptic, subcoriaceous, moderately bicolorous, long-acuminate at apex, rounded to truncate, often asymmetric at base, 33.5–63 x 10.5–16 cm, (2.7–)3–4.9x longer than wide, 1.3–2.6(–2.9)x longer than petiole, broadest close to middle, adaxial surface semiglossy, dark green, drying dull olive-green to olive-brown, abaxial surface semiglossy, paler than adaxial surface or yellowish green, drying glossy, light to medium reddish brown; primary lateral veins 14 to 48 per side, 1–3.5 cm apart, spreading from midrib at 45º–65º angles, downturned at midrib, curving upward out to margin, narrowly sunken adaxially, convex and darker than blade abaxially, drying lighter or concolorous adaxially, darker than blade abaxially; basal veins 2 per side, all free to base; interprimary veins often nearly as prominent as primary lateral veins, drying equal in color to primary lateral veins, sometimes with a stitched appearance abaxially; minor veins moderately obscure. INFLORESCENCE erect, 1 to 4 per axil; peduncle 1–4 cm x ca. 5 mm, much shorter than petiole, pale green to white, striate at apex, drying medium brown; spathe 8–13 cm, semiglossy, pale to dark green, white-streaked at base outside, longtapered at apex when immature, constricted above tube; spathe blade 6–8 cm, medium green to yellowgreen inside; spathe tube 2–5 cm, dark green outside, medium green inside; spadix cylindrical, 7–9 cm; pistillate portion pale yellow-green, 3.7 cm long on one side, 4.5 cm long on the other side, 1.6 cm diam. midway (dry); staminate portion white, slightly ellipsoid, 6–8 cm, to 11 mm diam. (dry); sterile staminate portion to 1 cm, 6–8 mm diam. (dry), slightly narrower than pistillate and fertile staminate portions; pistils 3.2–3.4 x 2.3–3 mm; ovary 6- to 7-locular, ovules with axile placentation, about 22 per locule. INFRUCTESCENCE with white (immature) berries.
The species is a member of the subgenus Philodendron, section Philodendron, subsection Canniphyllum and is characterized by its hemiepiphytic habit with leaves clustered near the top and usually held in a reflexed-spreading position, very short internodes obscured by pale cataphyll fibers, and oblong-elliptic leaf blades, truncate or rounded at the base, appearing very similar to those of the genus Rhodospatha, hence its epithet. Also characteristic is the long-tapered inflorescence with a white-striate spathe, green inside and out. Philodendron rhodospathiphyllum can be confused with P. heterocraspedon especially as a dried herbarium specimen. The latter species differs in having pendent longer and narrower blades usually drying much darker reddish brown. It also has more, closer primary lateral veins that curve upward at more acute angles. In addition, its inflorescences are longer (16–22 cm long as compared to 8–13 cm long in P. rhodospathiphyllum) and very pale green to white with the inside of the tube cherry-red.