SafePlants

Dwarf Mistletoes (Arceuthobium spp.)

The genus Arceuthobium, commonly known as dwarf mistletoes, comprises 42 species of parasitic plants. These plants primarily infect members of the Pinaceae and Cupressaceae families.

Considerations for Pets

• Dwarf mistletoe stems and seeds grow from pine branches.

Taxonomy and Nomenclature

• Scientific Name: Arceuthobium spp.
• Common Name: Dwarf Mistletoe
• Family: Viscaceae
• Taxonomic Rank: Genus
• The text mentions the Arceuthobium campylopodum-occidentale complex, indicating taxonomic challenges within the genus.
• One specific species mentioned is Arceuthobium americanum Nutt. ex Engelm.
• Subspecies: Arceuthobium tsugense Rosendahl G.N. Jones Subsp. tsugense

Distribution and Habitat

• Dwarf mistletoes are found in North America, Central America, Asia, Europe, and Africa.
• They are prevalent in many forests of western North America.
• In Nevada, they infect all coniferous tree species except incense cedar and junipers (which are infected by true mistletoes).
• They are a common problem in Colorado forests, particularly affecting ponderosa and lodgepole pines.
• Specific locations mentioned include Glacier View, Colorado; British Columbia (with subspecies on shore pine and mountain hemlock); and Central Mexico.
• They are native to western forests.

Ecological Role

• Dwarf mistletoes are parasitic plants, obtaining water and carbohydrates directly from their host trees.
• They cause serious and economically important diseases in conifers.
• They can significantly impact forest health and are considered a major problem in conifer species throughout the world.
• Natural disturbances and forestry practices can influence the spread of dwarf mistletoe.

Morphological Characteristics and Growth Habits

• Dwarf mistletoes are parasitic flowering plants that grow on the stems and branches of living conifers.
• They are very small, fleshy shrubs, usually no more than 2 cm (0.8 in.) tall.
• The common dwarf mistletoe, A. minutissimum, is one of the smallest plants with specialized water-conducting tissues, with flowering stems extending less than 3 cm.
• Infections can cause large witches' brooms, especially in Douglas-fir, ponderosa pine, lodgepole pine, western larch, and hemlock.
• Infected trees form distinct dwarf mistletoe infection centers.
• Small branch swelling is the first indication of dwarf mistletoe infection.

Interactions with Other Organisms

• They parasitize coniferous trees.
• Studies have examined the effects of southwestern ponderosa pine dwarf mistletoe (A. vaginatum) on bird communities.

Resources and Further Information

• Arizona Cooperative Extension (AZ1309)
• Management Guide for Dwarf Mistletoe (Arceuthobium spp.) – May 2004
• The Tree Line (Manitoba Conservation): 204-945-7866 or Toll Free 1-800-214-6497