Loranthus

Loranthus is a genus of mostly parasitic plants that grow on the branches of woody trees. It belongs to the family Loranthaceae, the showy mistletoe family. ^[1] In most earlier systematic treatments it contains all mistletoe species with bisexual flowers, though some species have reversed to unisexual flowers, while most modern systematists treat it as a monotypic genus with the only species Loranthus europaeus Jacq. - the summer mistletoe or European yellow mistletoe. In contrast to the wellknown European or Christmas mistletoe (Viscum album L., Santalaceae or Viscaceae) this species is deciduous. The systematic situation of Loranthus is not entirely clear, and some showy mistletoes in Asia may be true parts of this genus.

Ecology

Its zoophilic pollination is done by insects, birds and mammals, as bats, hummingbirds, parrots, butterflies, moths... The showy mistletoes can be found throughout the world. If the genus is treated in a restricted sense, the species L. europaeus is restricted to central-southeastern Europe and Asia Minor, where it often partially parasite species of oak. The fruits are an important food source for birds highly dependent on this food. Usually the birds are from specialized genera: Columbidae, Turdidae, etc. Birds eat the whole fruit and regurgitate seeds intact, expanding the seeds in the best conditions for germination (ornitochory). Secondly, the seed dispersal is carried out by monkeys, chipmunks, porcupines, opossums or fishes.

Sometimes a massive population of loranthus species in the same tree can cause death, but in most of cases their behavior is that of an epiphyte, favoring the autochthonous trees, that have developed resistance or strategies to reduce Loranthus species growth, against exotic species in the area without defenses. Some species of Loranthus, in the broad sense, are troublesome parasites, for example they occur in Kerala India as a menace on mango trees (Mangifera indica), a majority of the Anogeissus latifolia trees in the Biligirirangan Hills of Karnataka are infected by Loranthus sp and in Africa as pests in cocoa plantations. These plants grows strongly on ageing trees particularly somewhere in the middle of old branches. Once established, it steals minerals and water, as well as block sunlight by covering the encroached place. The flowers of Loranthus europaeus are small, green, usually have four to six parts and may be either unisexual or bisexual. Other species of a broader Loranthus have very large, showy flowers, with blooms in lively colours. The fruits are berries, usually containing a single seed, that are dispersed by birds.

Their presence is ecologically important for biodiversity of animal species depending of its fruits in unfavorable seasons, placing the specie's genus beginning food chain. An agricultural control method used is cutting the branch affected by Loranthus before it spreads to other branches of tree. For some Asian species using larvae of the Common Jezebel butterfly would be a method of natural control. The leaves of these loranths are food for the larvae. The larvae grow in scores and hence can quickly eat away the leaves of the mistletoe. Moreover, the larvae undergo metamorphosis later into beautiful butterflies called Common Jezebel which are very good pollinators and hence useful for trees. L. ferrugineus,is a variety traditionally used for the management of hypertension.^[2]

References