Passage: Upper pitchers are circular in cross section and widely infundibular in their upper half. They are much larger than lower pitchers, reaching 12 cm in height and 5.2 cm in width. The pitcher mouth is horizontal and orbicular. As in lower pitchers, the inner surface of the pitchers is wholly glandular. Wings are reduced to ribs that run down the front of the pitcher. In aerial pitchers, the flattened peristome is up 6 mm wide and bears more prominent teeth (≤1 mm long). The spur is usually simple and grows to 3.5 mm in length. Compared to lower pitchers, the lid in upper pitchers is similar in shape but longer, reaching 4.8 cm in length and 0.9 cm in width. It is held over the pitcher mouth at an angle of approximately 45 degrees.Nepenthes jamban has a racemose inflorescence. In male plants, the inflorescence may be up to 18 cm long. The female inflorescence has not been described. The rachis is up to 11.5 cm long, while the peduncle is up to 6.5 cm long. Pedicels are up to 1.4 cm long and bear a single flower. Sepals are elliptical and around 3.5 mm long. Mature fruits are up to 3 cm long and 6 mm wide. Seeds are filiform and around 2 cm long.Most parts of the plant are glabrous. Developing pitchers, tendrils, and inflorescences are densely covered with short brownish-grey hairs.The stem is characteristically purplish red. The leaves and inflorescence are light green to pale green. Lower pitchers range in colour from yellowish orange to bright red throughout. Upper pitchers are generally bright yellow with a yellow to orange peristome, and may be occasionally speckled on their inner surfaces.

Question: When does the species have more prominent teeth?
aerial pitchers