The Pitcher Plants

Fig. 3-2 Sarracenia purpurea ssp. purpurea showing the interior zones.

utilized by every species, secretion of nectar is universal among Sarracenia. In fact, in some cases the nectar secretion is so copious that the nectar is found in globules, particularly in zones 1 and 2 of the pitcher. Nectar glands occur on the outside surface of the pitcher, the upper inner surfaces of the pitcher and hood, as well as on the floral parts.

After an insect discovers the nectar and begins feeding on it, it will work its way to where the nectar is most abundant, in the vicinity of the pitcher's opening. As the insect feeds on the nectar produced on the rim of the opening, it may be enticed into the pitcher by the accumulation of nectar on the surface below the rim, inside the pitcher or along the underside of the hood. On the underside of the hood nectar glands are intermingled with hairs which point down toward the bottom of the pitcher. These downward pointing hairs do not provide a stable footing for the insects. It almost seems that some insects sense the possible danger and, rather than attempt to walk on the hairs, will stand on the rim and stretch as much as possible to reach the nectar. In the process they may lose their balance and tumble to the bottom of the pitcher. Other insects will attempt to carefully work their way around the hairs, feeding on the nectar, unaware that the path they are taking is leading them to the bottom of the pitcher. It is much easier for the insects to walk in the direction that the hairs are pointing than to walk against them. If the insect continues, it will reach zone 2 which, being smooth and waxy, offers no foothold. Hence, the insect falls to the bottom.

Sarracenia minor, S. leucophylla, and S. psittacina have visual lures known as fenestrations to attract insect prey. (Photo 3-3) Fenestrations are areas located on the hood and/or upper part of the pitchers which lack pigmentation and thus are translucent. The fenestrations allow light to enter the pitcher. Insects are apparently more likely to enter the lighted pitchers than if they are dark. When an insect reaches the rim it may see these translucent areas and, believing them to be openings, will fly from the rim to one of these "openings," only to smash into the fenestration and tumble down to the bottom of the pitcher. Alternatively, insects feeding on the nectar may follow a path which leads them to one of these "openings." Once there, the insect usually has no recourse, but to continue down into the pitcher because to get back to the rim it must walk against the pointed hairs.

Words cannot adequately describe the behavior of insects as they feed on the nectar and are unwittingly led to their death. At times during their feeding, the insects stop their activity as if they sense something ominous.

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