Mistletoe is the common name for obligate hemiparasitic plants in the order Santalales. They are attached to their host tree or shrub by a structure called the haustorium, through which they extract water and nutrients from the host plant. Their parasitic lifestyle has led to some dramatic changes in their metabolism.
The genus Arceuthobium, commonly called dwarf mistletoes, is a genus of 26 species of parasitic plants that parasitize members of Pinaceae and Cupressaceae in North America, Central America, Asia, Europe, and Africa. Of the 42 species that have been recognized, 39 and 21 of these are endemic to North America and the United States, respectively. They all have very reduced shoots and leaves with the bulk of the plant living under the host's bark. Recently the number of species within the genus has been reduced to 26 as a result of more detailed genetic analysis.
Arceuthobium americanum is a species of dwarf mistletoe known as American dwarf mistletoe and lodgepole-pine dwarf mistletoe. It is a common plant of western North America where it lives in high elevation pine forests. It is a parasitic plant which lives upon the Lodgepole Pine, particularly the subspecies Pinus contortus ssp. murrayana, the Tamarack Pine. This pine subspecies is most common in the Cascade Range and Sierra Nevada. The American dwarf mistletoe is a yellow-green coral-shaped structure above the surface of the tree's bark, while most of the parasite is beneath the bark. The seeds mature in late summer and disperse to nearby trees. This species has been found to explosively-disperse its seeds through thermogenesis.
Arceuthobium campylopodum is a species of dwarf mistletoe known as western dwarf mistletoe. It is native to the low to moderate elevation coniferous forests of western North America. It is a common parasite of several species of pine tree, including Jeffrey Pine, Ponderosa Pine, and Coulter Pine. The dwarf mistletoe is a greenish-yellow structure above the bark of the tree, while most of the plant is beneath the bark. Seeds mature during the fall and disperse to nearby trees.
Arceuthobium abietinum is a species of dwarf mistletoe known as fir dwarf mistletoe. It is native to western North America from Washington to New Mexico to northern Mexico, where it lives in coniferous forests as a parasite on various species of fir, particularly white fir, giant fir, and red fir. This is a small shrub which is visible as a network of scaly yellowish stems extending above the bark of its host tree. Most of the mistletoe is located inside the host tree, attached to it via haustoria, which tap the tree for water and nutrients. The leaves of the mistletoe are reduced to knobby scales on its surface. It is dioecious, with male and female mistletoe plants producing spikes of staminate and pistillate flowers, respectively. The fruit is a sticky berry a few millimeters long which explodes to disperse the seeds it contains several meters away from the parent plant and its host tree.
Arceuthobium divaricatum is a species of dwarf mistletoe known as pinyon dwarf mistletoe. It is native to the southwestern United States and Baja California, where it lives in woodlands as a parasite on various species of pine, particularly Colorado Pinyon and Single-leaf Pinyon. This is a small shrub which is visible as a network of scaly brown or greenish stems no more than 12 centimeters long extending above the bark of its host tree. Most of the mistletoe is located inside the host tree, attached to it via haustoria, which tap the tree for water and nutrients. The leaves of the mistletoe are reduced to thin scales on its surface. It is dioecious, with male and female mistletoe plants producing spikes of staminate and pistillate flowers, respectively. The fruit is a sticky berry a few millimeters long which explodes to disperse the seeds it contains several meters away from the parent plant and its host tree.
Arceuthobium douglasii is a species of dwarf mistletoe known as Douglas fir dwarf mistletoe. It is native to western North America from British Columbia to Texas to California, where it lives in forest and woodland as a parasite. It is found mostly on Douglas fir trees, but occasionally on fir, as well.
Arceuthobium littorum is a species of dwarf mistletoe known as coastal dwarf mistletoe. It is endemic to the coastline of northern California, where it lives as a parasite on Bishop Pine and Monterey Pine trees. This is a dark brown or greenish shrub which is visible as a network of scaly stems extending above the bark of its host tree. Most of the mistletoe is located inside the host tree, attached to it via haustoria, which tap the tree for water and nutrients. The leaves of the mistletoe are reduced to scales on its surface.
Arceuthobium siskiyouense is a species of dwarf mistletoe known as knobcone pine dwarf mistletoe. It is endemic to the Klamath Mountains of northern California and southern Oregon, where it lives as a parasite on knobcone pine trees. This is a brownish shrub which is visible as a network of scaly stems extending above the bark of its host tree. Most of the mistletoe is located inside the host tree, attached to it via haustoria, which tap the tree for water and nutrients. The leaves of the mistletoe are reduced to scales on its surface.
Phoradendron tomentosum, the leafy mistletoe, hairy mistletoe or Christmas mistletoe, is a plant parasite. It is characterized by its larger leaves and smaller berries than dwarf mistletoe. Leafy mistletoe seldom kill but they do rob their hosts of moisture and some minerals, causing stress during drought and reducing crop productions on fruit and nut trees. Leafy mistletoe has the ability to photosynthesize on its own but it relies on other plants in order to obtain its nutrients. It attaches itself to a tree and then grows haustoria, in order to get the food and water it needs.
Arceuthobium oxycedri, juniper dwarf mistletoe, is a hemiparasite of the family Santalaceae. It parasitizes members of the genus Juniperus, especially Juniperus oxycedrus and Juniperus communis.
Arceuthobium apachecum, called the "Apache dwarf mistletoe," is a parasitic plant found on the branches of pine trees in Arizona, New Mexico and Coahuila. It has yellowish-green stems up to 7 cm high.
Arceuthobium gillii, common name "Chihuahua pine dwarf mistletoe," is a parasitic plant found in Arizona, New Mexico, Chihuahua, Sonora and Sinaloa. It is found mostly on the Chihuahua pine, Pinus leiophylla var chihuahuana.
Arceuthobium microcarpum, called the "western spruce dwarf mistletoe," is a parasitic plant known only from Arizona and New Mexico. It is found mostly on spruce trees but also occasionally on Rocky Mountain bristlecone pine. The specific epithet "microcarpum" means "small fruited," in reference to the berries, which are only 3.5 mm long.
Arceuthobium vaginatum, called the "sheathed dwarf mistletoe" or "southwestern dwarf mistletoe" is a parasitic plant found in the southwestern United States and northwestern and central Mexico. It generally is found on pine trees.
Callophrys johnsoni, the Johnson's hairstreak, is a butterfly of the family Lycaenidae. It is found in North America from British Columbia south to central California. The habitat consists of coniferous forests.
Arceuthobium pusillum is a perennial, obligate parasitic plant in the sandalwood family. Its common names include Dwarf mistletoe or Eastern dwarf mistletoe. It is one of the most widespread dwarf mistletoes within its range which covers the eastern United States and Canada, from Saskatchewan to Nova Scotia and New Jersey. The species name "pusillum" derives from Latin "pusillus", meaning very small.
Daniel Lee Nickrent is an American botanist, working in plant evolutionary biology, including the subdisciplines of genomics, phylogenetics, systematics, population genetics, and taxonomy. A major focus has been parasitic flowering plants, particularly of the sandalwood order (Santalales). His interest in photographic documentation and photographic databases has led to several photographic databases including Parasitic Plant Connection, Phytoimages, Plant Checklist for the Rocky Mountain National Park, and Plant Checklist for the Crab Orchard National Wildlife Refuge.
