Restriction of Viscum Album to Few Phorophytes in a Habitat with Diverse Type of Tree Species

Research Article

Austin J Plant Biol. 2015; 1(2): 1010.

Restriction of Viscum Album to Few Phorophytes in a Habitat with Diverse Type of Tree Species

Ahmed Z and Dutt HC*

Department of Plant Ecology Laboratory and Botany, University of Jammu, India

*Corresponding author: Dutt HC, Department of Plant Ecology Laboratory and Botany, University of Jammu, Jammu-180006, India

Received: July 27, 2015; Accepted: December 07, 2015; Published: December 16, 2015


Viscum known for 464 species is distributed from temperate to tropical world as is a hemi-parasite on tree species. Commonly called as mistletoes, the members of the group show normal parasitic, facultative, or rarely tripartite associations. Mistletoes are also known for auto parasitism, where individuals of the same species parasitize on the same species of mistletoe growing on the host trees. In the present study, V. album is reported on three cultivated host species i.e. Juglans regia L., Prunus armeniaca L. and Salix alba L. only, however, the study area is characterized with the number of other tree species also. In order to understand the specificity of the hemi-parasite on these three phorophytes, a seed germination test of V. album has been conducted on other eight tree species in the same geographical area.

Keywords: Temperate NW himalaya; Parasitism; Phorophyte; Autoparasite; Host specificity


Viscum is a hemi-parasite on several tree species and comprises about 464 species widely distributed from temperate to tropical climates in Europe, Africa, Asia, and Australia [1]. Morphologically, V. album is 30–100cm long, dichotomously branched with yellowishgreen, opposite, strap-shaped, entire, leathery leaves measuring 2–8 X 0.8–2.5cm. During reproductive phase species bears insect – pollinated, unisexual, yellowish-green flowers measuring 2–3 mm in diameter. The fruit is white or yellow berries containing one (very rarely several) seed embedded in the very sticky, glutinous fruit pulp [2]. Traditionally, the genus has been placed in family Viscaceae, but on the basis of molecular studies now-a-days all the members of Viscaceae are merged into the Sandalwood family i.e., Santalaceae [3,4]. In general the pattern of host specificity in mistletoes covers a wide spectrum from highly host specific to host generalists [5,6,7]. Some mistletoe parasitizes a large number of hosts in different families. e.g., V. album ssp. album on more than 450 host species and a few mistletoes e.g., some dwarf mistletoes parasitize only one host species [8,9]. The host specificity of dwarf mistletoes may be a useful taxonomic character for distinguishing between host populations [10,11,12,13]. However, some mistletoe is not common on noncultivated plants [14]. In addition, many species have been thought of as key species for animals which eat honey and fruit [15,16]. Another fascinating effect of mistletoe host specificity is the propensity of mistletoes to parasitize mistletoe. This facultative association is termed as hyperparasitism [17]. Hyperparasitic mistletoes are recorded from Loranthaceae and Santalaceae [18]. A number of species of Phoradendron and Viscum also show hyper-parasitism [19,1]. Even more amazing are the rare tripartite associations where a mistletoe parasitizes a mistletoe that is parasitizing another mistletoe on a host tree [18]. When mistletoe on another mistletoe becomes an obligate association, this is termed epiparasitism viz Phacellaria [20,17]. Parasitism by an individual of the same species is called auto parasitism. Auto parasitism occurs frequently in Loranthaceae as well as in Santalaceae (Figure 1).