Hemiepiphytic or rarely terrestrial; stem appressed-climbing or scandent; sap pale orange to orange-brown; internodes long, weakly glossy, 1.5–25 x 1– 4 cm, longer than broad, gray-green to green or light brown; epidermis scurfy, conspicuously transverse-fissured, drying yellowish tan and flaking; roots to 3 mm diam., few per node, drying dark reddish brown with loose epidermis; cataphylls 12–28 cm, unribbed, 1-ribbed, or sharply 2-ribbed, rounded and apiculate at apex, green or yellow-green, drying dark rusty brown, deciduous. LEAVES spreading; petioles 21– 46 cm x 4–8 mm (dry), terete, sulcate toward base, slightly flattened and sometimes sulcate toward apex, medium green, matte, weakly striate, drying golden-tan, often longitudinally wrinkled; blades ovate, coriaceous to moderately coriaceous, short-acuminate at apex, deeply cordate at base, 26.5–56 x 16– 32(–39) cm, 1.2–1.7x longer than wide, 0.8– 1.3(–1.6)x as long as petiole, broadest near the middle, adaxial surface semi-glossy, dark green, drying glossy and olive-green to medium olive-tan, abaxial surface matte to weakly glossy, paler, drying slightly less glossy and barely paler than adaxially; anterior lobe 20–42 x 16–32(–39) cm, 1.9–3.1x longer than posterior lobe; posterior lobes 8.5–16 x 7.5–15 cm, usually rounded, sometimes slightly rectangular at apex; sinus parabolic to spatulate, 5– 13 cm deep; midrib flat and paler adaxially, round-raised and paler abaxially; primary lateral veins 4 to 7 per side, 2–5 cm apart, departing midrib at 50º–60º, down-turned at midrib then fairly straight but curving upward to within 1.5 cm of the margin; basal veins 4 to 7 pairs per side, 4 coalesced 1–3 cm, 2 coalesced up to 7 cm, posterior rib not naked or naked up to 3 cm, 1 vein free to base; interprimary veins obvious but less prominent than primary lateral veins; secondary veins distinct, fine, parallel to primary lateral veins. INFLORESCENCE small, erect, 1 to 3 per axil; peduncle 5–12 cm 3 2–3 mm (dry), much shorter than petiole, pale to medium green sometimes tinged red, drying light reddish brown; spathe 5–7.5 cm, barely constricted, drying rusty reddish brown; spathe blade 3.5–4.5 cm, greenish white to yellowish cream outside, creamy yellow inside; spathe tube 2–3.5 cm, green outside, rosy red to maroon inside; spadix cylindrical, weakly exserted from the spathe, barely constricted near base of fertile staminate portion, 5.3–5.8 cm; pistillate portion pale green becoming white, 2–2.5 cm 3 3–4 mm (dry); staminate portion creamy white, 3.2– 3.7 cm 3 3–5 mm (dry); sterile staminate portion ca. 1 cm, ca. 5 mm diam. (dry); pistils ca. 0.8 x 0.8 mm; ovary 4-locular, ovules with basal placentation, 1 per locule. INFRUCTESCENCE not seen.
The species is a member of subgenus Philodendron, section Macrobelium, subsection Glossophyllum, series Ovata Croat and is characterized by its weakly glossy, transversely fissured, gray-green stem with fairly long internodes, hence the epithet canicaule (from the Latin ‘‘canus’’ meaning grayish white and ‘‘caulis’’ meaning stem). Also distinctive are the long, variably ribbed, deciduous cataphylls, the terete petioles sulcate at the base, the cordate leaf blades that are matte abaxially with well-developed posterior ribs, and the small inflorescences. Philodendron canicaule may be confused with P. polliciforme Croat & D. C. Bay because their leaf blades are similar in shape and both have small spathes (4.5–8.5 cm long). They differ, however, in that the latter species usually has shorter internodes, cataphylls that are quite red and have at least the basal portion persisting, leaf blades drying dull olivegreen without any red color, and an inflorescence with a red spathe.
IUCN Red List category. Conservation for Philodendron canicaule must be considered as Near Threatened (NT) according to IUCN Red List criteria (IUCN, 2001). Although locally common in the area of the type locality, it is not yet known from other sites in Colombia. It is possible that the species is more widespread than is currently known, because much of the Pacific slope is still poorly known.