Terrestrial or hemiepiphytic; stem scandent or appressed-climbing; internodes 4–12 3 2–3.5 cm, longer than broad, medium green, transversely fissured, becoming brown and scurfy, drying brownish tan, transversely fissured; roots few per node, drying medium brown; cataphylls to 30 cm, sharply 1-ribbed, green, drying dark reddish brown, deciduous. LEAVES erect-spreading to spreading; petioles 17– 52 cm 3 5–9 mm (dry), subterete, dark green, short dark-lineate, drying olive-green to light brown; geniculum to 3 cm, drying darker than petiole and somewhat shrivelled; blades narrow triangular-ovate, moderately coriaceous, long-acuminate at apex, shallowly cordate at base, 28–73 3 8–30 cm, 2–3.53 longer than wide, 1.3–1.63 longer than petiole, adaxial surface semiglossy, dark green, drying semiglossy and olive-green, abaxial surface matte and much paler than adaxially, drying dull and barely paler than adaxially; sinus triangular to spatulate, 0.5–5 cm deep; midrib flat and yellowish white adaxially, narrowly rounded, paler than blade, short dark-lineate abaxially; primary lateral veins 9 to 10 per side, 3 cm apart toward base to 7.5 cm apart toward apex, spreading from midrib at 60u–70u angles, downturned at midrib, curving gradually out to margins, sunken and paler than blade, drying concolorous adaxially, convex and paler than blade, drying darker than blade, yellowish brown abaxially; basal veins 2 per side, both free to base; minor veins moderately distinct, arising mostly from the midrib. INFLORESCENCES to 7 per axil, enclosed in a prophyll; peduncle 7–8 cm 3 2–5 mm (dry), medium green, faintly lineate; spathe apiculate (apiculum to 5 mm), 8–13 cm, slightly constricted above tube; spathe blade 5–6 cm, white, often with red to red-violet spots and tinged red along margin outside, burgundy toward base and white in upper 2/3 inside; spathe tube 3–5 cm, yellowish white outside, tinged red along margin, deep burgundy inside; spadix somewhat exserted at anthesis, sessile, slightly clavate, 9–11 cm; pistillate portion pale green, cylindrical, 1.5–2 cm long on one side, 2.4–3.5 cm long on the other side, 5–6 mm diam. (dry); staminate portion cream, clavate, 6.8–7.5 cm 3 8–12 mm at widest point (ca. 1 cm from apex) (dry), broader than pistillate portion; sterile staminate portion not apparent; pistils ca. 2 mm; ovary 7- to 9-locular, ovules with basal placentation, 1 per locule. INFRUCTESCENCE unknown.
Philodendron trojitense is a member of subgenus Philodendron, section Macrobelium, subsection Glossophyllum, series Ovata and is characterized by its scandent terrestrial habit; stems that are scurfy, brown, and transversely fissured; and long, narrow triangular-ovate leaf blades that are matte abaxially and have relatively few, widely spaced, primary lateral veins. In addition, the yellowish white, red-violet-spotted inflorescences grow in a cluster enclosed in a persistent prophyll. Philodendron trojitense is somewhat similar to P. suberosum in that the epidermis of the stems of both species is highly fissured and they both have shallowly cordate leaf blades with all the basal veins free to the base. The latter species differs, however, in having leaf blades that are wider (1.3–1.83 longer than wide as compared to 2–3.53 longer than wide for P. trojitense) with more primary lateral veins much closer together. The inflorescences also differ because in P. suberosum they are shorter, more blunted at the apex, and solid dark red outside.
IUCN Red List category. Conservation for Philodendron trojitense must be considered as Near Threatened (NT) according to IUCN Red List criteria (IUCN, 2001). Although reasonably 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.