Seasonal heterophylly and leaf gland features in Triphyophyllum (Dioncophyllaceae), a new carnivorous plant genus

Abstract

Triphyophyllum peltatum (Dioncophyllaceae), a tropical-West African liane, is heterophyllous, bearing leaves of three types, two on juvenile, non-climbing, short shoots, and the third on the mature axis. The short shoots produce mostly eglandular, lanceolate leaves, but just before the height of the rainy season small clusters of relatively ephemeral, glandular, filiform leaves are formed. These glandular leaves bear both stalked and sessile glands, and they act as efficient trapping organs for the prey, mostly flying insects and other small animals. The stalked glands, of which there are two size classes, are the most anatomically elaborate known in the plant kingdom. Structurally there are similarities with the stalked glands of Drosophyllum and Drosera. At maturity they carry secretion droplets, and stimulation by the prey leads to further secretion. The secretions contain a range of hydrolytic enzymes. During sonic periods of its development Triphyophyllum is probably carnivorous. An important source of nutrients is thus tapped which could be significant in making possible an earlier transition from the juvenile to the rapidly-climbing adult form. The Dioncophyllaceae, contains two other monotypic genera, neither with the carnivorous habit. Triphyophyllum is considered as an ecological African analogue of Nepenthes.