Mistletoes are considered keystone species on woodlands and savannas worldwide, providing a food resource for a diversified fauna, as well as a nutrient-enriched litter. Infections can be large (∼1–3 m) and, in some parts of the Amazonian savannas, parasitize up to 70% of hosts locally. Despite these facts, biomass of mistletoes is rarely investigated. Here we constructed allometric models to predict the biomass stock of the shrubby mistletoe Psittacanthus plagiophyllus in an Amazonian savanna. In addition, we determined whether host size could be used as a proxy for mistletoe biomass. Finally, we compared the biomass of mistletoes with that of trees, to evaluate their relative importance. We have shown that: (1) biomass of leaves (46.1% ± 13.5%) are as important as of stems (47.8% ± 13.5%), and relative contribution of stems increases as plant grows; (2) the model including width, breadth and vertical depth was the best (SE = 0.39, R2 = 0.9) for predicting individual mistletoe biomass; (3) mistletoe load and biomass per host had a positive, but weak (R2 = 0.11 and 0.09, respectively), relationship with host size, and thus such host information is a poor predictor of mistletoe biomass; and (4) in comparison with trees, mistletoes constituted less than 0.15% (0.5–22 kg ha−1) of the total above-ground biomass, suggesting that this life-form is irrelevant to the local biomass stock despite its unequivocal biological importance.

A botanical survey conducted from 2003 to 2007 showed the occurrence of the acacia strap flower and the Oriental mistletoe plant in different regions in Jordan. Acacia strap flower was found parasitizing 26 plant species belonging to 12 families. Oriental mistletoe attacked 14 plant species from eight families. Parasitized species ranged from wild shrubs to fruit and forest trees. Eleven Fabaceae species were parasitized by acacia strap flower, whereas Oriental mistletoe parasitized six Rosaceae species. Caper, pomegranate, white weeping broom, and white willow were attacked by both parasites. Infection by both parasites resulted in mortality of host plants in many cases. Hosts severely attacked by acacia strap flower were African jujube, Australian pine, chinaberry, Christ thorn jujube, common jujube, oleander, poinciana, sumac, tamarisk, terebinth, and white weeping broom. Oriental mistletoe heavily parasitized almond, mosphilla, olive, Palestine buckthorn, pomegranate, and white weeping broom. Results indicated the high potential of both parasites to spread and attack new hosts in the absence of control measures.