Harmony and Conflict in the Living World - Alexander F. Skutch [54]
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in length, each pitcher is attached to its stalk at the top, rather than at the base, as in all other pitcher plants. It has a wide, ridged lid, a corrugated rim, two wings along the front, and, below the downward-projecting teeth of the rim, a ledge extending around the inside with its acute edge jutting into the cavity, forming a kind of contracted neck. Small insects, mainly ants attracted by its nectar glands, fall into the bowl and are digested but, again, it is difficult to separate the effect of enzymes secreted by the pitcher from that of bacteria.
Very different from the foregoing passive traps are the ten species of Genlisea, which grow chiefly in Brazil, the Guianas, and Cuba, with two in western Africa. Although placed in the bladderwort family (Lentibulariaceae) on the basis of its floral structure, it is quite different, too, from the other genera in this family. All its species are small, rootless plants of swamps and marshes, where they grow in shallow water, with the inflorescences rising above it, as in the aquatic bladderworts. Like Cephalotus, Genlisea has two kinds of leaves: linear or spatulate foliage leaves and trap leaves, closely intermixed along a slender rhizome. In length these traps range from less than an inch (about 2 cm.) to four or five inches (10-12.5 cm.). From a tiny, bulbous base rises a long, slender neck, and at the open top of this little flask diverge two slender arms, each a ribbon folded into a tube and twisted into a spiral, those on opposite sides of the flask wound in opposite directions. The apposed edges of the ribbons are held apart by swollen cells placed at intervals, leaving between them funnel-like openings guarded by inwardly directed hairs. The tiny copepods, nematode worms, or spiders that venture through the funnels find themselves in a narrow passage bristling, from the tips of the arms down through the neck to the bulbous bottom of the flask, with inwardly directed hairs arranged in transverse rows, and covered with mucilage from many glands. Whether these glands also secrete digestive enzymes appears not to be known, but victims only halfway down the neck are already well advanced in disintegration. These traps lined with inwardly pointing hairs have been likened to lobster pots or eel
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Genlisea sp., branch with foliage and traps and details of trap enlarged
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traps, which are crude structures in comparison to these marvelously complex little snares, perhaps the most intricate among all the carnivorous plants.
Adhesive Leaves
Instead of pitfall traps or other closed structures, a number of carnivorous plants catch their prey on the exposed, sticky surfaces of their leaves. Among them are two species of Byblis, in a family of their own, the Byblidaceae, confined to western and northern Australia. The larger of them, B. gigantea, is a half-shrub up to twenty inches (50 cm.) high, which grows in the drier, better drained parts of sandy swamps. Arising from a slender rhizome, the sparsely branched stem bears linear leaves four to eight inches (10 to 20 cm.) long and, on stalks springing from their axils, violet or rose-colored flowers with five-lobed corollas. In cross section the leaves are triangular, with rounded edges. On the two lower sides of the triangle are many stalked glands that secrete abundant mucilage. The sessile glands on all faces of the leaf have a less viscous secretion that appears to be digestive, and they also give evidence of absorption, on the strength of which Byblis is included among the true carnivorous plants.
Not all plants with sticky glands to which small creatures adhere and die digest and derive