Again, scribed by Taisha. She writes:
Frost and crisp air have greeted me the past few mornings when starting my commute to UBC, two signs in these early days of December that the holidays are approaching. Around the city, empty lots are being turned into temporary sites for Christmas tree sales, lights are being strung up, and wreaths are being hung upon doors. In the spirit of the holidays, I've chosen to write an entry on Viscum album, or European mistletoe! The images of this species are courtesy of stevieiriswattii!@Flickr, who uploaded them to the Botany Photo of the Day Flickr Pool (image 1 | image 2).
Viscum album, a member of the sandalwood family, is a hemi-parasitic evergreen shrub. Hemi-parasites are plants that receive additional nutrients via a haustorial attachment to a host, but are also able to photosynthesize. In the case of mistletoe, their parasitism can lower the host tree's vigour, induce premature mortality, reduce the quality of wood, or induce water stress. As a species, Viscum album is able to infect a large number of host plants. There are five or six subspecies of Viscum album recognized, differing in part by host specificity. For example, Viscum album subsp. abietis (shown today) is a parasite on Abies (fir) species (in today's case, silver fir or Abies alba). Similarly, Viscum album subsp. austriacum parasitizes Pinus (pine) species and rarely Larix (larch) or Picea (spruce) species. Other subspecies parasitize flowering trees or different conifers.
European mistletoe is dioecious and insect-pollinated. The flowers are yellowish to green and inconspicuous. The fleshy white berries ripen through the early winter in Europe, and are bird-dispersed from late winter to spring. Birds do eat the berries, but digestion is not necessary for seed germination. Instead of eating the berries, birds will sometimes disperse the fruit by dropping the berry in flight or while on the tree. The mucilaginous viscin on the outside of the berry allows it to stick to the bark of the tree, where it will eventually germinate and infect (see Kahle-Zuber, D. 2008. Biology and evolution of the European mistletoe (Viscum album). (PDF) Doctoral dissertation, ETH Zurich, No. 18080.
Mistletoe appears extensively in mythology and folklore. To the ancient druids of Britain, mistletoe was a symbol of magical powers and medicinal properties. From Norse legend, Balder (a Norse god and the son of goddess, Frigga), was killed by mistletoe. However, his life was later restored and Frigga, in her joy, said that anyone who passed under mistletoe should receive a kiss. This custom remains today, with kisses being shared under the mistletoe which is commonly used as a Christmas decoration. Where this truly originates, I'm uncertain, although it is known to have been part of Christmas customs since at least the seventeenth century.
If you live in Vancouver, and are looking to decorate for the holidays, the Friends of the Garden are selling hand-made wreaths at the Shop in the Garden until December 23, 2013, or until quantities last!