[MPWG] Mistletoe has it all! Happy Holidays!

[Patricia_DeAngelis at fws.gov]

Dear Listserve Members:

The holidays are around the corner! So this message is infused with 
holiday cheer and thoughts about medicinal plants, like mistletoe, that 
are important to many of us at this time (or any time) of the year. 

Happy Holidays and I look forward to more exciting discussions and 
information sharing over the MPWG listserve in 2008! Thanks to all of you 
who find the time to make medicinal plant conservation happen. 

-Patricia

Patricia S. De Angelis, Ph.D.
Botanist - Division of Scientific Authority
Chair - Plant Conservation Alliance - Medicinal Plant Working Group
US Fish & Wildlife Service
4401 N. Fairfax Dr., Suite 110
Arlington, VA  22203
703-358-1708 x1753
FAX: 703-358-2276
Working for the conservation and sustainable use of our green natural 
resources.
<www.nps.gov/plants/medicinal>

Mistletoe has it all! 

Mistletoe is a parasitic plant of the genus Phoradendron, with at least 24 
species native to the United States, Puerto Rico and the Virgin Islands. 
It’s considered medicinal by some and invasive by others. Myths and folk 
uses of mistletoe abound as part of many ancient and modern traditions 
around the world. Here is an article by the USGS that highlights many of 
the interesting facets of mistletoe. I've also included several links at 
the end to other articles that venerate or denigrate this famous (or 
infamous) medicinal plant:

USGS 2007: Not Just for Kissing: Mistletoe and Birds, Bees, and Other 
Beasts
http://www.usgs.gov/newsroom/special/mistletoe/

Perhaps some of you have already experienced a sweet holiday smooch or two 
under the Christmas mistletoe, enjoying this fairly old kissing ritual for 
people. But mistletoe is important in other vital ways: it provides 
essential food, cover, and nesting sites for an amazing number of critters 
in the United States and elsewhere. In fact, says Rob Bennetts, a USGS 
research scientist, some animals couldn’t even survive without mistletoe, 
including some birds, butterflies, and insects. But first, a little bit 
about the plant. The white-berried Christmas mistletoe we hang so 
hopefully in places where our sweethearts will find us lingering, is just 
one of more than 1,300 species of mistletoe worldwide. Globally, more than 
20 mistletoe species are endangered. Two kinds of mistletoes are native to 
the United States: the American mistletoe (the one commonly associated 
with our kissing customs) and the dwarf mistletoe. American mistletoe is 
found from New Jersey to Florida and west through Texas. The dwarf 
mistletoe, much smaller than its kissing cousin, is found from central 
Canada and southeastern Alaska to Honduras and Hispaniola, but most 
species are found in western United States and Mexico. Mistletoe is no 
newcomer to this country: excavations of packrat middens reveal that dwarf 
mistletoes have been part of our forests for more than 20,000 years. Some 
fossil pollen grains even indicate that the plant has been here for 
millions of years. Says Bennetts: "Mistletoes should be viewed as a 
natural component of healthy forest ecosystems, of which they have been a 
part for thousands, if not millions of years."

Thief of the Tree
The thing that all mistletoes have in common is this: all grow as 
parasites on the branches of trees and shrubs. In fact, the American 
mistletoe’s scientific name, Phoradendron, means "thief of the tree" in 
Greek. The plant is aptly named: it begins its life as a handily sticky 
seed that often hitchhikes to a new host tree on a bird beak or feather or 
on mammal fur. In addition to hitchhiking, the dwarf mistletoe also has 
another dandy way of traveling to a new host tree: the seeds of this 
mistletoe will, like tiny holiday poppers, explode from ripe berries, 
shooting a distance as far as 50 feet. One researcher said that if you put 
ripe berries in a paper bag and shake it, it sounds just like popping 
popcorn. For the most part, the mistletoe is pretty darn cavalier about 
what host tree it finds — dwarf mistletoes like most kinds of conifers; 
American mistletoes are found on an incredible variety of trees. Once on a 
host tree, the mistletoe sends out roots that penetrate the tree and 
eventually starts pirating some of the host tree’s nutrients and minerals. 
In actuality, though, mistletoes are not true parasites; instead they are 
what scientists call "hemi-parasites" because most of them have the green 
leaves necessary for photosynthesis. Still, it seems like a pretty lazy 
life for most mistletoes: a little photosynthesis here and there and a lot 
of food and water stolen from their unsuspecting benefactor trees. 
Eventually, mistletoes grow into thick masses of branching, misshapen 
stems, giving rise to a popular name of witches’ brooms, or the apt Navajo 
name of "basket on high." 

Birds and the Mistletoe Trees
The plant’s common name — mistletoe — is derived from early observations 
that mistletoe would often appear in places where birds had left their 
droppings. "Mistel" in the Anglo-Saxon word for "dung," and "tan" is the 
word for "Twig." Thus, mistletoe means "dung-on-a-twig." Yet even though 
bird droppings cannot spontaneously generate mistletoe plants, birds are 
an important part of mistletoe life history — and vice versa. A surprising 
variety of birds use or rely on mistletoe. In Bennetts’ and other studies, 
a high abundance of dwarf mistletoe in a forest means that more kinds and 
numbers of birds inhabit that forest. Also, since the lifespan of 
mistletoe-laden trees is considerably shorter than trees where the plant 
is absent, a higher number of tree snags occupy mistletoe-laden woods. Not 
surprisingly, this means that more — one study documented at least three 
times as many -- cavity-nesting birds live in forests with abundant 
mistletoes. The phainopeplas, a silky flycatcher, are beautiful birds that 
live in the desert areas of the Southwest and West and are especially 
dependent on mistletoe. Diane Larson, a USGS researcher, studied 
mistletoes and birds in Arizona. "I found that phainopeplas, which rely on 
mistletoe almost exclusively for food during the winter, were also the 
species most likely to disperse the mistletoe seeds to sites suitable for 
germination and establishment. Both the bird and the plant benefited from 
this relationship," says Larson. This year, USGS is beginning a study on 
phainopeplas and mistletoes that live on acacia and mesquite trees in the 
desert. Todd Esque, a USGS researcher, said that his goal is to understand 
the distribution of the host trees in relation to mistletoe patterns and 
bird behavior. "We know the relationship is mutually beneficial for both 
species," said Esque. Some research indicates that if mistletoe-berry 
production is poor, these birds may not breed the following spring. But 
the phainopepla is just one of many birds that eat mistletoe berries; 
others include grouse, mourning doves, bluebirds, evening grosbeaks, 
robins, and pigeons. Naturalist and writer John Muir noted American robins 
eating mistletoe in the mountains of California in the late 1890’s. Wrote 
Muir: "I found most of the robins cowering on the lee side of the larger 
branches of the trees, where the snow could not fall on them, while two or 
three of the more venturesome were making desperate efforts to get at the 
mistletoe berries by clinging to the underside of the snow-covered masses, 
back downward, something like woodpeckers." Birds also find mistletoe a 
great place for nesting, especially the dense witches’ brooms. In fact, 
northern and Mexican spotted owls and other raptors show a marked 
preference for witches’ brooms as nesting sites. In one study, 43 percent 
of spotted owl nests were associated with witches’ brooms. Similarly, a 
USGS researcher found that 64 percent of all Cooper’s hawk nests in 
northeastern Oregon were in mistletoe. Other raptors that use witches’ 
brooms as nesting sites include great gray owls, long-eared owls, 
goshawks, and sharp-shinned hawks. Likewise, some migratory birds also 
nest in witches’ broom — gray jay, northern beardless-tyrannulet, red 
crossbills, house wrens, mourning doves, pygmy nuthatches, chickadees, 
Western tanagers, chipping sparrows, hermit thrushes, Cassin’s finches, 
and pine siskins. "A well-disguised nest provides protection against 
predators such as the great horned owls," Bennetts said. 

Bees, Butterflies, and Others
According to butterfly expert and Colorado State University professor Paul 
Opler, three kinds of butterflies in the United States are entirely 
dependent on mistletoes for their survival: the great purple hairstreak, 
the thicket haristreak, and the Johnson’s hairstreak. The great purple 
hairstreak, says Opler, is the only butterfly in the United States that 
feeds on American mistletoe, the Christmas mistletoe. This beautiful 
butterfly lays its eggs on the mistletoe, where the resulting caterpillars 
thrive one a mistletoe diet. The caterpillars of the other two butterflies 
feed on dwarf mistletoes. The Johnson’s hairstreak, restricted to just the 
Pacific states, is usually found in association with old-growth conifer 
forests, the same places spotted owls prefer. The caterpillars of these 
butterflies closely mimic the appearance of the mistletoe with their 
mottled green and olive shades. Like people, the butterflies of these 
species use mistletoe for courtship rituals. After courting and mating in 
the mistletoe high in the canopy, the adults leave their eggs behind in 
the mistletoe. The adults of all three species drink nectar from the 
mistletoe flowers. Mistletoe is also important nectar and pollen plant for 
honeybees and other native bees, says Erik Erikson, a bee researcher at 
the USDA Bee Research Lab. Mistletoe flowers, says Erikson, often provides 
the first pollen available in the spring for the hungry bees. "We look 
upon it as an important starter food source for the bees," said Erikson. 
Wind and insects are important mistletoe pollinators. Although hundreds of 
kinds of insects carry mistletoe pollen, only a few dozen are important 
pollinators; these include a variety of flies, ants, and beetles. Yet 
other insects eat the shoots, fruits, and seeds of the mistletoe, 
including some that feed exclusively on the plant. Exclusive 
mistletoe-eaters include a twig beetle, several thrip species, and a plant 
bug whose coloration mimics dwarf mistletoe fruits. In addition, at least 
four mite species seem to be exclusively associated with dwarf mistletoe. 

And Then There’s the Mammals
Don’t try it at home, kids and grown-ups — mistletoe is toxic to people, 
but the berries and leaves of mistletoe provide high-protein fodder for 
many mammals, especially in autumn and winter when other foods are scarce. 
Researchers have documented that animals such as elk, cattle and deer eat 
mistletoe during winter when fresh foliage is rare. In Texas, some 
ranchers even consider mistletoe on mesquite as an insurance forage crop, 
which the ranchers remove from the trees for cattle food when other forage 
is scarce. Other mammals that eat mistletoe include squirrels, chipmunks, 
and even porcupines, some of which are deliriously fond of the plant. A 
variety of squirrels, including red squirrels, Abert squirrels and flying 
squirrels often use witches brooms for cover and nesting sites. 

A Blessing or a Bane?
Not everyone likes mistletoe. Many commercial foresters consider the dwarf 
mistletoe as a disease that reduces the growth rates of commercially 
important conifer species, such as the ponderosa pine. Ecologists, though, 
point out that mistletoes are not a disease; instead, they are a native 
group of plants that have been around thousands, or even millions, of 
years. Blessing or bane, it is certain that mistletoe is not spreading 
like wildfire -- in fact, mistletoe spreads only about 2 feet per year. 
One study indicated that a 1.5-acre patch of mistletoe took about 60 to 70 
years to form. Likewise, the death of an individual tree from dwarf 
mistletoe may take several decades, and widespread infestation of a forest 
stand may take centuries. Bennetts believes that the conflict with forest 
management and the perspective of mistletoes being a forest disease really 
only comes into play when the management objectives are to maximize timber 
harvest. Otherwise, he says, mistletoes have many positive attributes, 
including tremendous benefits for native wildlife. Thus, he says, when not 
in conflict with commercial timber management objectives, mistletoes 
should be viewed as a natural component of healthy forest ecosystems. Says 
Bennetts: "I had the privilege of working with a biologist who had spent 
more than 50 years working on mistletoes. He began his work with the 
intent of finding a way to control this ‘forest pest,’ but in his later 
years, he even introduced dwarf mistletoe to some of the trees in his yard 
because he had grown to love this plant for what it is . . . a fascinating 
and natural part of forest ecosystem." 

For More Information Contact: 
Catherine Puckett
Phone: 707-442-1319
email: catherine_puckett at usgs.gov
Todd Esque
Phone: (702) 564-4506
Fax: (702) 564-4600 
email: todd_esque at usgs.gov
The USGS serves the nation by providing reliable scientific information to 
describe and understand the Earth; minimize loss of life and property from 
natural disasters; manage water, biological, energy, and mineral 
resources; and enhance and protect our quality of life. 
***USGS***

More information on mistletoe:

Genus: Phoradendron 
USDA-NRCS PLANTS Database (2007)
http://plants.usda.gov/java/profile?symbol=PHORA

Non-wood products from organisms associated with temperate broad-leaved 
trees: Mistletoe
Ciesla (2002)
http://www.fao.org/DOCREP/005/Y4351E/y4351e0d.htm

State trees and state flowers
U.S. National Arboretum (2006)
http://www.usna.usda.gov/Gardens/collections/statetreeflower.html

What Does Mistletoe Have To Do With Christmas?
Tainter, Frank (2002)
http://www.apsnet.org/online/feature/mistletoe/

'Tis the Season for Mistletoe
MSU Extension Service (1997)
http://msucares.com/newsletters/pests/infobytes/19971202.htm

Mistletoe: Good for More Than Free Kisses
HerbalGram. 2005;68:50-59 American Botanical Council
http://content.herbalgram.org/youngliving/herbalgram/articleview.asp?a=2901
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.plantconservation.org/pipermail/mpwg_lists.plantconservation.org/attachments/20071221/10d09da4/attachment.html>