Nepenthes Aristolochioides - Description - Pitchers

Pitchers

Nepenthes aristolochioides is noted for exhibiting relatively little dimorphism between its lower and upper pitchers. Rosette and lower pitchers are only briefly produced on small rosettes before the plant begins to climb, or on offshoots from the climbing stem. They arise from the ends of the tendrils, forming a 3–5 mm wide curve. They are broadly infundibular in the lower two-thirds and globose above, forming a dome above the pitcher opening. They reach 7 cm in height and 3 cm in width. A pair of wings (≤9 mm wide) runs down the front of the pitcher, either covering the length of the trap's ventral surface or being restricted to the upper part only. These wings bear fringe elements up to 10 mm long. The pitcher mouth is orbicular to ovate and up to 1.5 cm in diameter. It has a horizontal, oblique or almost vertical insertion. The glandular region covers almost the entire inner surface of the pitcher, but is often missing from the uppermost parts of the pitcher dome. The waxy zone typical of many Nepenthes species is absent. Digestive glands are overarched; the lower ones measure 0.2–0.3 mm in diameter and are present at a density of around 200/cm2, whereas the upper ones are smaller and present at a density of around 500/cm2. The flattened peristome is broad, greatly incurved, and up to 20 mm wide. Its ribs are spaced up to 0.5 mm apart. Its inner margin is lined with small teeth that are curled at their apices and are 2–3 times as long as they are broad. The inner portion of the peristome accounts for around 82% of its total cross-sectional surface length. The pitcher lid or operculum is orbicular-cordate or ovate, up to 1.5 cm wide, and bears no appendages. Large nectar glands are present on the lid's entire lower surface, particularly around the midline. Three prominent veins are usually present on either side of the lid's midline. A broad and flattened spur (≤7 mm long) is inserted at the base of the lid. It has been variously described as either branched or unbranched (simple).

Upper pitchers gradually arise from the ends of the tendrils, forming a 10 mm wide curve. They are narrowly infundibular in the lower half and utriculate above, with a pronounced dome above the pitcher orifice. The ventral face of the trap is often noticeably flattened and is around 30% thicker than the wall of the translucent dome. Aerial traps are larger than their terrestrial counterparts, reaching 15 cm in height and 8 cm in width. They typically bear ribs in place of wings, although these may not be apparent at all. The pitcher mouth is subapical, ovate to circular, and measures up to 4 cm in diameter. It is angled even more steeply than in lower pitchers and may be positioned almost vertically. The glandular region usually covers the basal two-thirds of the pitcher cup's inner surface, or the pitcher may be wholly glandular. Digestive glands are slightly overarched; those near the bottom are 0.3–0.4 mm in diameter and occur at a density of around 200/cm2, whereas the upper ones are 0.2–0.3 mm in diameter and occur at a density of around 250/cm2. The peristome, which is up to 20 mm wide, is expanded, incurved, and internally flattened, forming an "entrance corridor" similar to a lobster pot. It extends for up to 2 mm on its outer margin, which is rounded. There is often a gap of up to 5 mm between the two lobes of the peristome near the base of the lid. The peristome bears ribs up to 0.8 mm high and spaced up to 0.8 mm apart, which terminate in indistinct teeth that are 2–3 times as long as they are broad. Large nectaries are located between the ribs. The pitcher lid is orbicular to ovate and is often held roughly horizontally, at a right angle to the pitcher orifice. It has a rounded to emarginate apex and a slightly cordate base, and measures up to 4 cm in length by 3 cm in width. It has no appendages, but bears numerous nectar glands, which are scattered quite evenly across the entire lower surface of the lid. These nectaries are circular to shortly elliptic and thinly bordered, measuring around 0.3 mm in diameter. They become slightly larger and more densely packed around the midline. Their rims are visibly asymmetric and are highest near the apical end of the lid. Three to four prominent veins are present on either side of the lid's midline. The spur is broad and flattened, measuring up to 10 mm in length. It has 2–4 acute points at its apex, and has been variously described as either simple or branched.