reaching 21.1 cm in height and 9.4 cm in width. Wings are reduced to narrow ribs that run the whole length of the pitcher cup. The peristome is cylindrical and up to 4.4 cm wide. As in lower pitchers, it bears ribs up to 0.5 mm high and spaced up to 1 mm apart. The lid is up to 7.9 cm long and 5.6 cm wide. The spur, reported to be bifid (with each branch being two-branched itself) and up to 16 mm long, is inserted near the base of the lid. Nepenthes rigidifolia has a racemose inflorescence. Female inflorescences have not been recorded in the wild. In male inflorescences, the rachis measures around 3.9 cm in length and the peduncle around 4.2 cm. Bracts are approximately 9 mm long by 4 mm wide. Flowers are produced on two-flowered partial peduncles bearing filiform basal bracteoles up to 2 mm long. The unbranched portion of the partial peduncles is up to 5 mm long. The pedicels themselves are up to 6 mm long. Tepals are ovate-oblong and measure up to 5 mm in length by 3 mm in width. The androphore is around 4 mm long and 1 mm in diameter. Nepenthes rigidifolia is one of the few Nepenthes species known to occasionally produce multiple inflorescences concurrently on a single stem. This unusual reproductive habit has also been observed in N. alba, N. ampullaria, N. attenboroughii, N. benstonei, N. philippinensis, N. sanguinea, and N. thai. The development of the indumentum is variable in this species. Some plants are completely glabrous, while others bear a covering of orange to brown hairs (≤1 mm long) on the stem, pitchers, tendrils, and portions of the inflorescence. Developing rosette pitchers and tendrils are often densely pubescent, while developing pitchers produced on the climbing stem are tomentose. The pitcher lid may be glabrous or pubescent. The peduncle is typically slightly pubescent, and the partial peduncles, pedicels, bracts, tepals, and androphores densely pubescent. The laminae are green, whereas the stem, midribs and tendrils range from green, through yellow, to orange or even red. Terrestrial pitchers have a distinctive colouration: their outer surface is black, brown, or purple, with numerous large flecks of greenish-white, brown, or orange. The upper part of the inner surface ranges from white to light green or light yellow, with dark red to black blotches. Both the peristome and lid may be dark red,