"In the case of the mistletoe, which draws its nourishment from certain trees, which has to be transported by certain birds...Its is therefore, of the highest importance to gain a clear insight into the means of modification and coadaptation. "
Darwin (1859) - Origin of species
Mistletoes are aerial parasitic plants of shrubs and trees. To be more precise, they belong to the Sandalwood order (Santalales) in which only part (5) of the eighteen families developed the aerial parasitism (Nickrent, 2011). All species of mistletoe invades the xylem of hosts using a modified root called haustorium, being able to photosynthesize. Because of that, they are only half parasites - hemiparasites.
In Brazil, mistletoes are called “ervas-de-passarinho”. Something like a bird's herb. Birds, indeed, are their main seed dispersers, eating the fruits and regurgitating, defecating of bill wiping the seeds onto tree branches. Mistletoes may also be dispersed through autochory (as in Arceuthobium ), or by mammals, as in Tristerix corymbosus, solely dispersed by the marsupial gliroid dromicops in Argentina and Chile (Amico and Aizen, 2000).
The parasitic plants, unsuspecting people may think mistletoes are ugly creatures, which only exist to cause harm to their hosts. However, according to Dr. David Watson (Charles Sturt University, Australia), they are more Dryad than Dracula, acting as facilitators for other plants and offering food and shelter for fauna, including insects, spiders, birds, mammals and many others (Watson, 2009, 2001). Besides that, recent studies have shown that mistletoes also produce a nutrient-enriched litter, which is a precious source of minerals for plants in some soil-poor ecosystems (March and Watson, 2007).
Complexity is in the details. A host is infected by a mistletoe, which hosts the eggs of a butterfly, which are being infected by a tiny parasitoid wasp.
Amico, G., Aizen, MA, 2000. Mistletoe seed dispersal by a marsupial. Nature 408, 929-930.
March, WA, Watson, DM, 2007. Parasites boost productivity: Effects of mistletoe on litterfall dynamics in a temperate Australian forest. Oecology 154, 339–347.
Nickrent, DL, 2011. Santalales (Including Mistletoes), in: Encyclopedia of Life Sciences. John Wiley & Sons, Ltd, Chichester, UK, pp. 1–6.
Watson, DM, 2009. Parasitic plants as facilitators: More Dryad than Dracula? J.Ecol. 97, 1151–1159.
Watson, DM, 2001. Mistletoe—A keystone resource in forests and woodlands worldwide. Annu. Rev. Ecol. System 32, 219–249.
Grow your own mistletoe
Growing mistletoe can seem crazy suggestion. Believe me! It is worth it! First step is choosing a native, non-aggressive species. In the images below I did the exercise to cultivate Psittacanthus biternatus (except the last photo, which is of P. plagiophyllus ) on a Murici tree (Byrsonima crassifolia ). In the photo description is the number of months that have passed from germination to the respective stage. Hope I encourage you to grow these fantastic plants!