Week Eight: Dwarf Mistletoe

Common Name: Dwarf Mistletoe

Scientific Name: Arceuthobium sp.

Fun Fact: Dwarf mistletoe fruits each contain a single bullet-shaped seed. As the fruit grows, tension tightens on the seed and eventually it flies outward, shooting toward a new host at up to 56 miles per hour. The dwarf mistletoe embryo, it can be said, is a feisty youth.

Domain: Eukaryota

Kingdom: Plantae

Phylum: Magnoliophyta

Class: Magnoliopsida

Order: Santalales

Family: Viscaceae

Genus: Arceuthobium

Description: Dwarf mistletoe is a different genus than its better-known and also parasitic relative. The plant itself is as small yellow structure that latches onto the branches of conifer trees, its natural host. Almost all species of conifer tree are vulnerable to infection except for cedar and juniper, which can be colonised by the dwarf’s relative, true mistletoe. Signs of infection in host trees include swelling of the bark, the visible yellow shoots, and branch growth said to be shaped like a “witch’s broom.” Eventually, the host tree will begin to die from the top down until branches, trunk, and roots all are dry husks.

Environment: Dwarf mistletoe is found in conifer forests in all of southern Canada, Alaska, the western United States from Texas to Washington State, and the northern states from Maine to Minnesota and down to Pennsylvania.

Reproduction & Development:  In accordance with the Fun Fact, dwarf mistletoe produces fruits containing small, sticky projectile seeds capable of flying 56 miles per hour and landing 50 feet from their original position. Once on a new host tree, the plant establishes itself as a parasite (see Nutrition) and is visible within two to four years of infecting the tree. After one to two more years, the plant is sexually mature and begins to fruit.

Nutrition: Dwarf mistletoe has little to no chlorophyll of its own, and therefore cannot perform photosynthesis to a degree sufficient to feed itself. This is why it is forced to parasitize conifers. The plant injects parasitic roots called “hautoria” into the branches of its host. These structures leech nutrients from the vascular tissue of the host tree until the tree dies.