HOST‐PARASITE RESEMBLANCE IN AUSTRALIAN MISTLETOES: THE CASE FOR CRYPTIC MIMICRY

Abstract

A feature of Australian loranthaceous mistletoes is the close vegetative similarity, especially of the leaves, between many species of mistletoe and their usual hosts. The phenomenon involves, particularly, several dominant Australian genera of host trees such as Eucalyptus, Acacia, and Casuarina, and a number of mistletoe genera, including Amyema, Lysiana, Muellerina, Diplatia, and Dendrophthoe. It also occurs in virtually all ecological associations from wet sclerophyll forest to arid woodland. The apparent vegetative of their hosts by many Australian species of Loranthaceae is a popular topic for discussion among naturalists, but rather few references occur in the literature, and experimental studies of the basis of the have been undertaken. Among earlier authors, Drummond (1840) and Hemsley (1896) commented on vegetative similarity of various mistletoes and their hosts. Moore (1899) and Le Plastrier (1920) considered the to be a protective adaptation, and although Moore (1899) commented further on the apparent palatability of the mistletoe, he suggested that herbivores might be attracted to the plants by showy, nectar-rich flowers. Blakely (1922) denied the existence of host in mistletoes, but he interpreted the concept of differently from other authors. He ignored the overall similarity between host and parasite at the species or population level, and discussed the variability or plasticity within mistletoe populations and the extent to which it corresponded with variation in the host population. After finding correlation in the variability, he concluded that mistletoes showed no marked power of mimicry of their hosts. The, primary object of this paper is to elucidate the nature of the apparent vegetative by many Australian loranthaceous mistletoes of their respective hosts. A full review of the subject of in higher plants has not been attempted, but the nature of other known or suspected cases is discussed as background for the present study.