mistletoes

Mistletoes are a group of obligate hemi-parasitic plants in the order Santalales. They attach to the tissues of host trees or shrubs using specialized structures called haustoria, from which they withdraw water and minerals, while still performing photosynthesis for their carbon needs.

The term mistletoe covers several genera, including Viscum, Phoradendron, and Arceuthobium. Viscum includes European mistletoe (Viscum album), while Phoradendron species are common in the Americas. Arceuthobium, though often called dwarf mistletoe, comprises conifer parasites. Most mistletoes are evergreen and form leafy clumps or ball-like crowns on their hosts.

Mistletoes produce berries that are typically white, yellow, or pink and are dispersed mainly by birds. The seeds usually germinate on a host branch after being deposited by a bird; a germinating seed then forms a haustorium that invades the host to tap into the xylem and sometimes phloem. Flowers are often small and can be dioecious, with separate male and female plants.

Ecologically, mistletoes can be keystone resources, providing food for birds and shelter for other organisms, especially in winter. They can reduce host vigor when abundant and may cause branch dieback; management in forestry often involves pruning or removal of infected limbs, though complete control can be challenging.

Culturally, mistletoe holds a longstanding place in folklore and modern celebrations, notably as a Christmas plant in parts of Europe. Conservation status varies by species and region, with habitat loss affecting some populations while others remain widespread.