Although less conspicuous in general than in Anthurium or in P. subg. Meconostigma, the petiolar scars on the stems of P. subg. Philodendron are nonetheless clearly visible unless covered with persisting cataphylls. In contrast to Anthurium the petiolar scars of P. subg. Philodendron are generally not much inclined inward but rather are more or less flush with the general contour of the stem surface. They may be moderately inconspicuous as in P. rothschuhianum (Fig. 9) or moderately conspicuous as in P. davidsonii (Fig. 10). Philodendron petioles are typically much swollen at the base so the scar is usually broader than the rest of the petiole itself. Petiole scars vary from (0.5)1-4(7.5) cm high and (0.7)1-5(7.0) cm diam. but they are rarely more than 3 cm high and 3.5 cm diam. The average height and width for those species studied (32 species) is 2 cm high and 2.4 cm diam. The scar of inflorescence, situated medially on the petiolar scar, is often quite conspicuous (Fig. 5) and deep. Of ecological significance is the fact that these deep holes left when the inflorescence falls off are the point of entry for phytofagous insects, especially stem borers which infect the older portions and sometimes the younger portions of the stems.
Intravaginal squamulae (Dahlgren & Clifford, 1982), so prominent in P. subg. Meconostigma, are usually present but often very inconspicuous in P. subg. Philodendron (Fig. 11). Mayo (1991) points out differences between P. subg. Philodendron and P. subg. Meconostigma in this regard. He stresses this as evidence of differences in two contrasting patterns of stem elongation (see discussion under stem above). In P. subg. Philodendron the intravaginal squamulae (Fig. 11) are always immediately above the cataphyll (prophyll of Ray, 1987a), whereas in P. subg. Meconostigma the intravaginal squammulae are immediately below the cataphyll scars and also often around the scar for the foliage leaf as well.