SafePlants

Douglas-fir Dwarf Mistletoe (Arceuthobium douglasii)

Arceuthobium douglasii, commonly known as Douglas-fir dwarf mistletoe, is a parasitic plant primarily affecting Douglas-fir trees.

Considerations for Pets

• Forms "witches' brooms" which alter the architecture of branches on infected trees.
• Small aerial shoots.

Considerations for Children

• Forms "witches' brooms" which alter the architecture of branches on infected trees.
• Small aerial shoots.

Taxonomy and Nomenclature

• Scientific Name: Arceuthobium douglasii Engelm.
• Common Name: Douglas-fir dwarf mistletoe
• Division: Magnoliophyta
• Class: Santalales
• French Name: Faux-gui du Douglas vert

Distribution and Habitat

• Native to western North America, ranging from British Columbia to Texas.
• Common in Colorado forests.
• Found in the Okanagan and Similkameen valleys and in the Creston area, with isolated stands near Lytton.

Ecological Role

• A destructive native parasite of Douglas-fir trees.
• Considered a primary disease agent affecting Douglas-fir.
• Causes serious losses in many Douglas-fir stands.

Morphological Characteristics and Growth Habits

• An obligate parasite with an endophytic 'root' system ramifying within the host branch.
• Infects Douglas-fir shoots, which are olive green.
• Induces the formation of witches' brooms on infected trees, altering branch biomass and architecture.

Interactions with Other Organisms

• Primarily infects Douglas-fir (Pseudotsuga menziesii).
• Also affects ponderosa and lodgepole pines, and can attack pion.
• Wildlife uses witches' brooms associated with infection by Douglas-fir dwarf mistletoe.

Quirky Facts

• The infection of Douglas-fir dwarf mistletoe can lead to the formation of "witches' brooms" on the host tree, which are dense, broom-like growths of twigs and branches.