Category: Trees

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Kissing Under the Dung Twig

Juniper Mistletoe
Phoradendron juniperinum
in Red Rock Canyon, Nevada
Courtesy Stan Shebs, Photographer
This file is licensed under the
Creative Commons
Attribution-Share Alike 2.5 Generic license.

Close-up of Juniper Mistletoe
Phoradendron juniperinum
in Red Rock Canyon, Nevada
Courtesy Stan Shebs, Photographer
This file is licensed under the
Creative Commons
Attribution-Share Alike 2.5 Generic license.

Holly: Hi, I’m Holly Strand.

Together with poinsettia and holly, mistletoe is an iconic Christmas plant. The term mistletoe doesn’t refer to a single species or even a single lineage of plants. Instead there are over 1300 species belonging to 5 different plant families. All mistletoes are partially or mostly parasitic –they obtain water and minerals from a host tree, shrub or cactus via specialized stems. Sometimes mistletoe stems may branch into tangled masses called witches brooms. These gnarled structures offer nesting habitat for songbirds, raptors, and squirrels and can provide forage for deer and elk.

In Utah, Juniper mistletoe is the most common species. You’ll find it across the Colorado Plateau and along the Wasatch Front. Acacia mistletoe is much rarer and found only in the Beaver Dam Mountains west of St. George. Both of these species are leafless and spiky looking but many types of mistletoe have green leaves to support photosynthesis.

Most mistletoes reproduce with the help of birds that eat their fruit. Mistletoe seeds pass through the bird’s digestive system and are deposited on new branches where they stick and germinate. This explains the mistletoe’s strange name which is Anglo Saxon for “dung twig”.

Considering its humble origins in bird poop, mistletoe has made quite a name for itself. Like a botanical Forest Gump, it keeps cropping up throughout history in myths, cultural traditions and even medicines.

  • In Norse mythology, the overprotective Goddess Frigg went to all the living creatures on earth, making them pledge not to harm her beloved son Baldur. But she overlooked the mistletoe. When mischievous Loki discovered this, he arranged that Balder’s brother would throw an arrow made of mistletoe to strike Balder—killing him, of course.
  • In Virgil’s epic poem the Aeneid, mistletoe was the “Golden Bough” which allowed Aeneas to pass into the Underworld.
  • The ancient Druids revered both oak trees and the mistletoe that grew in them. They believed that a potion prepared from mistletoe would make barren animals reproduce. And they used mistletoe as an antidote to all kinds of poisons.


    • Throughout the ages, mistletoe was used to treat many medicinal conditions such as epilepsy, infertility, hypertension and arthritis. Today, many claim that mistletoe stimulates the immune system, helping the body fight more efficiently against cancer and other diseases.

    While it was originally hung in doorways to attract good health and good fortune, by the 18th century mistletoe morphed into a Christmas decoration. We don’t know exactly how the custom of kissing under the mistletoe –or dung twig—evolved, but I’m certainly glad it did!

    For pictures and sources for this program and archives of past programs, go to www.wildaboututah.org For Wild About Utah, I’m Holly Strand.

    For Wild About Utah, I’m Holly Strand.

    Credits:

    Image: Courtesy Wikipedia, Stan Shebs, Photographer
    Text: Holly Strand

    Sources & Additional Reading:

    Drury, Susan. 1987. “Customs and Beliefs Associated with Christmas Evergreens: A Preliminary Survey” Folklore 98.2 pp. 194-199., Abstract

    Fertig, Walter. 2006 “Utah Plant Families: The Mistletoes (Viscaceae)” Volume 29 No. 6 Sego Lily (Newsletter of the Utah Native Plant Society) Utah Native Plant Society

    Horneber MA, Bueschel G, Huber R, Linde K, Rostock M. 2008. “Mistletoe therapy in oncology.” https://www.ncbi.nlm.nih.gov/pubmed/18425885 Cochrane Database Syst Rev. 2008 Apr 16;(2):CD003297. doi: 10.1002/14651858.CD003297.pub2. PMID: 18425885 [PubMed – indexed for MEDLINE]

    Milius, Susan. 2002. Science News. “Mistletoe, of all things, helps juniper trees.” Web edition: January 2, 2002. Print edition: January 5, 2002; Vol.161 #1 (p. 6) https://www.sciencenews.org/view/generic/id/2334/description/Mistletoe,_of_all_things,_helps_juniper_trees

    Watson, David. M. “Mistletoe—A Keystone Resource in Forests and Woodlands Worldwide.” 2001. Annu. Rev. Ecol. Syst. 2001. 32:219–491, https://rspb.royalsocietypublishing.org/content/early/2012/07/03/rspb.2012.0856.full

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    Red leaves in autumn: What’s in it for the tree?

    Extension.usu.edu, https://treebrowser.org/index.cfm?controller=final&action=details&key=469&sortby=CommonName” alt=”Red leaves in autumn: What’s in it for the tree?: Canyon or Big-Toothed Maple leaves in late summer, Acer grandidentatum, Courtesy Michael Kuhns, https://Extension.usu.edu”>Extension.usu.edu, https://treebrowser.org/index.cfm?controller=final&action=details&key=469&sortby=CommonName” width=”250″ height=”192″ border=”0″ /> Canyon or Big-Toothed Maple
    leaves in late summer
    Acer grandidentatum
    Courtesy Michael Kuhns
    Extension.usu.edu     Canyon or Big-Toothed Maple leaves in fall, Acer grandidentatum, Courtesy Michael Kuhns, Extension.usu.eduCanyon or Big-Toothed Maple
    leaves in fall
    Acer grandidentatum
    Courtesy Michael Kuhns
    Extension.usu.edu

    Hi, I’m Holly Strand.

    As early as 4th grade, children learn that leaves are green because of the high concentration of chlorophyll relative to other pigments. And that autumn leaves turn color because the breakdown of chorophyll molecules unmasks the yellow, orange and red pigments that remain.

    This simple and satisfying explanation has existed for awhile. However, research in the past 15 years has uncovered a much more complicated story. Leaf physiologists jumped from the question, “What makes autumn leaves so colorful?” And started to ask the evolutionary question: “What’s the purpose behind this autumn color fest?” “What’s in it for the tree itself?”

    The group of pigments that produce yellow or orange are called carotenoids. The carotenoids are in the leaf throughout the growing season but only become apparent with the breakdown of chlorophyll into colorless metabolites. However, the red pigments—or anthocyanins– are produced in the leaf AFTER much of the chlorophyll is lost. This active production of new anthocyanins led scientists to believe that the pigment must be performing a critical function.

    Just what function is still not known but many hypotheses exist. One is that anthocyanins act as a sunscreen shielding leaf tissues against the harmful effects of sunlight. The risk of sun damage is particularly high in fall because of the lack of chlorophyll protection and because there is increased light due to a thinning canopy. Without sun damage, the leaves can continue to absorb nutrients right up to the end.

    Another possibility is that anthocyanins function as an antioxidant shield. Plant chloroplasts produce fewer free radicals when shielded from green wavelengths of light. Anthocyanins absorb the green wavelengths. Without anthocyanin, a surplus of superoxides could cause damage to the plant cell structure.

    Lastly, there is the coevolution hypotheses. Aphids and other insects feed, carry viruses and bacteria. So red coloration was an adaptation developed by trees designed to lighten their insect load. The red leaves signal to insects that the tree is not a suitable host. The coevolution theory is supported in part because trees with autumn colors tend to be the ones with a history of interaction with aphids. Also, experiments have shown that most aphids strongly prefer green leaves over red leaves. In some cases anthocyanin may be positively correlated with a form of chemical defense.

    However, when considering this last theory, remember that species perceive color differently. To the human eye, a tree may be a brilliant autumn shade of red. To the aphid, that same tree might be an indistinguishable gray. Further the insect may be avoiding red leaves because of differences in texture, taste, scent, texture or something else that is important to an aphid.

    Whatever the reason is, I hope you are enjoying Utah’s colorful reds and yellows.

    For links to current research and a Forest Service update on fall color around the state, go to www.wildaboututah.org.

    For Wild About Utah, I’m Holly Strand.

    Credits:


    Images: Courtesy and Copyright 2003 Michael Kuhns, Extension.usu.edu
    Text: Holly Strand

    Sources & Additional Reading


    USDA Forest Service Fall Colors web site for the Intermountain Region https://www.fs.usda.gov/detail/r4/recreation/?cid=FSBDEV3_016189

    Archetti, M., Doring, T. F., Hagen, S. B., Hughes, N. M., Leather, S.
    R., Lee, D. W., Lev-Yadun, S., Manetas, Y., Ougham, H. J., Schaberg,
    P. G., Thomas, Howard (2009). Unravelling the evolution of autumn
    colours: an interdisciplinary approach. Trends in Ecology and
    Evolution, 24, (3), 166-173. https://digitalcommons.fiu.edu/cas_bio/38/

    Chittka L, Döring TF (2007) Are Autumn Foliage Colors Red Signals to
    Aphids? PLoS Biol 5(8): 187. https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0050187

    Lee, David and Kevin S. Gould Why Leaves Turn Red. American
    Scientist, Volume 90. 524-531 https://harvardforest.fas.harvard.edu/sites/harvardforest.fas.harvard.edu/files/leaves/2002_11_leaf_article.pdf

    Gunnell, JayDee, Reese, Julene, Ask a Specialist: What Causes the Fall Leaves to Change Color?, USU Cooperative Extension, https://extension.usu.edu/htm/news-multimedia/articleID=18662

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    Aflame with Color

    Aflame with Color: Canyon or Big-Toothed Maple In a natural landscape Acer grandidentatum, Courtesy Michael Kuhns Extension.usu.edu
    Canyon or Big-Toothed Maple
    In a natural landscape
    Acer grandidentatum
    Courtesy Michael Kuhns
    Extension.usu.edu

    Holly: Hi, I’m Holly Strand from Stokes Nature Center in beautiful Logan Canyon.

    The canyons and valleys of Utah will soon be awash with brilliant fall hues. Cascades of red, orange and gold will blanket the hillsides as the weather turns cooler and morning frost dusts the mountain ridges.

    The Canyon Maple is one of Utah’s main sources of autumn color. Like most maple species, its leaves are carved into deep lobes. The leaves are medium-to-bright green now, but soon the entire tree will glow with spectacular color.
    Canyon maple is found throughout Utah at medium elevations between 4,500 to 7,500 feet. It tends to grow on lower slopes and canyon bottoms in the mountains in association with Douglas-fir and junipers.

    Its scientific name, Acer grandidentatum [AY-ser gran-dih-den-TAY-tum], means “Big Tooth”, referring to the tree’s distinctive lobed leaves with large, toothed margins. In fact, bigtooth maple is another common name for this species.

    Canyon or Big-Toothed Maple In a natural landscape Acer grandidentatum  Courtesy Michael Kuhns Extension.usu.edu
    Canyon or Big-Toothed Maple
    In a natural landscape
    Acer grandidentatum
    Courtesy Michael Kuhns
    Extension.usu.edu

    Some think that he canyon maple is related to the sugar maple of the northeastern and midwestern United States,” says forestry professor Mike Kuhns of Utah State University’s Department of Wildland Resources. It’s possible that long ago, the Rocky Mountains rose up and isolated a sugar maple population that eventually evolved into a unique species.

    The canyon maple rivals its eastern relatives in fall color but does it produce sap suitable for tasty, syrup-covered waffles and pancakes? Back in 1970s, a group of scientists set out to determine just that. The trees were tapped and yielded plenty of sticky liquid. The color was very light, resembling light honey and the flavor was delicate and fruity, almost like pineapple. However, it was notably less sweet than the northeastern sugar maple. Of 30 panelists from Utah who participated in a taste test, 57 percent preferred eastern sugar maple syrup but the remaining 43 percent preferred canyon maple syrup.

    Canyon or Big-Toothed Maple leaves in late summer Acer grandidentatum Courtesy Michael Kuhns
    Canyon or Big-Toothed Maple
    leaves in late summer
    Acer grandidentatum
    Courtesy Michael Kuhns

    The researchers concluded that while canyon maple sap was not practical for large-scale syrup production it might be enjoyable for individuals to try on a small scale on private land within its habitat range.

    Syrup aside, the medium-sized tree thrives in Utah’s residential landscapes, parks and urban areas, as well as in the wild. Its year-round beauty, hardiness and manageable size make it a perennial favorite in the Beehive State.

    Thanks to the USU College of Natural Resources for supporting research and development of this Wild About Utah topic.

    For Wild About Utah and Stokes Nature Center, I’m Holly Strand.
    Credits:

    Canyon or Big-Toothed Maple leaves in late summer & fall Acer grandidentatum  Courtesy Michael Kuhns Extension.usu.edu
    Canyon or Big-Toothed Maple
    leaves in late summer & fall
    Acer grandidentatum
    Courtesy Michael Kuhns
    Extension.usu.edu

    Image: Courtesy and Copyright 2003 Michael Kuhns, Extension.usu.edu

    Text: Holly Strand & Mary-Ann Muffoletto, Stokes Nature Center

    Sources & Additional Reading:

     

    Barker, Phillip A.; Salunkhe, D. K. 1974. Maple syrup from bigtooth maple. Journal of Forestry. 72(8): 491-492. [9065] https://www.ingentaconnect.com/content/saf/jof/1974/00000072/00000008/art00016

    Kuhns, Michael. 2003. Canyon Maple: A Tree For the Interior West,” USU Forestry Extension, https://extension.usu.edu/forestry/HomeTown/Select_CanyonMaple.htm [2009, September 16].

    Tollefson, Jennifer E. 2006. Acer grandidentatum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/ [2009, September 16]

    Acer grandidentatum – Bigtooth Maple, Water-wise Plants for Utah Landscapes, https://www.waterwiseplants.utah.gov/default.asp?p=PlantInfo&Plant=17

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    Gall Insects

    Gall Insects: Click to view Rabbit Brush Galls made by a tephritid fly (Aciurina trixa.) Image courtesy and copyright Jim Cane
    Rabbit Brush Galls
    made by a tephritid fly Aciurina trixa
    Image courtesy and Copyright Jim Cane
    Fly identification courtesy Gary Dodson

    Does Utah have more Gauls than Caesar conquered? Certainly not Gaulish peoples of the ancient Roman Empire, but yes, galls of the vegetal kind we have aplenty. Galls are small protuberant growths on plants that are induced hormonally by insects, nematodes, and microbes. For its resident juvenile insect, the gall is a sort of edible fortress.

    Some plant galls made by insects persist into winter, when they are more apparent to the naturalist’s eye. Looking at just rabbitbrush, you can find a menagerie of galls shaped like peas, pineapples and spindles that were formed from leaves, buds and stems. No growing tissue is immune to galling. The morphology of a gall is often diagnostic for the species of juvenile insect within. Gall-making insects are all tiny and include gall midges and tephritid flies, cynipid gall wasps, various nondescript moths, and any number of aphids and their kin.

    One aphid causes the unsightly brown galls on branch tips of blue spruce, a bane to homeowners. Another aphid forms the pea-shaped galls that swell leaf petioles of aspens and cottonwoods. On sagebrush can be found a leaf gall whose soft surface surpasses that of a puppy’s ear. Oaks and willows host a remarkable diversity of galls. One oak gall was formerly used for tanning leather and making inks because it is rich in tannic acids. The Hessian fly is of grave agricultural importance today because its stem galls weaken wheat stems, causing them to lodge over.

    Click to view Tephritid fly (Aciurina bigeloviae) galls on Rabbitbrush. Image courtesy and copyright Jim Cane
    Tephritid fly Aciurina bigeloviae
    galls on Rabbitbrush
    Image courtesy and Copyright Jim Cane
    Fly identification courtesy Gary Dodson

    But these are exceptions; most galls are of little or no ecological or economic importance. For that reason, most galling insects remain understudied by all but a handful of passionate specialists. Finding plant galls is easy, and once you begin to notice them, you will find it hard to stop. There is no guide to Utah’s plant galls, but we list several starting references for you on our web site.

    This is Linda Kervin for Bridgerland Audubon Society.

    Credits:

    Photos: Courtesy and Copyright Jim Cane
    Text: Jim Cane, Bridgerland Audubon Society
    Additional Reading:
    Sagebrush Gall made by the fly Rhopalomyia pomum, https://bugguide.net/node/view/200946
    Robert P. Wawrzynski, Jeffrey D. Hahn, and Mark E. Ascerno, Insect and Mite Galls, WW-01009 2005,
    University of Minnesota Extension, https://www.extension.umn.edu/distribution/horticulture/dg1009.html

    Click to view Willow Cone Gall Midge. Image courtesy and copyright Jim Cane
    Willow Cone Gall Midge
    Image Courtesy and Copyright Jim Cane

    Field Guide to Plant Galls of California and Other Western States by Ron Russo
    ISBN: 978-0-520-24886-1 https://www.amazon.com/California-Western-States-Natural-History/dp/0520248864
    Gall, Wikipedia, Wikimedia Foundation, Inc., https://en.wikipedia.org/wiki/Gall (Accessed Dec 2010)
    Gagné R (1989) The plant-feeding gall midges of North America. Cornell University Press, Ithaca
    https://www.amazon.com/Plant-Feeding-Midges-North-America-Comstock/dp/0801419182