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Article - for release the week of
Culbert - Extension Horticulture Agent
WHAT’S THAT IN MY TREE ?
The tourist season in Okeechobee coincides with the time when the foliage on our trees is the thinnest. It’s also a busy time here at the Extension office with requests for information about all that stuff growing in trees. People are concerned that all these unusual things are killing their trees, and want to know how they should be removed.
Only few of these plants are harmful. Most are "just there", while
a few of them are actually rare plants that deserve recognition. Information
for today’s column comes from
Mistletoe grows in Laurel Oaks, Hickories and a few other hardwood trees. It is very apparent in the thin foliage of our semi-deciduous trees at this time of year. It appears as a darker green ball of foliage on an otherwise bare tree canopy. This is one of the few things found growing on our trees which can harm our urban forest.
Christmas mistletoe (Phoradendron serotinum) is found growing locally. In a healthy tree, mistletoe may not be much of a concern, but if the tree is stressed from hurricane damage, construction impacts, disease or old age, this parasite can take its toll.
Mistletoe can be cut out of the tree canopy. The branch should be cut back several inches below the connection point. This kind of trimming may not be possible on larger limbs of the tree. Scientists have found that a spray containing the plant growth regulator, ethephon, can be used as a selective mistletoe management spray. Its use on local trees has been approved by the EPA.
Christmas Mistletoe photo by Dan Culbert
Spanish Moss photo courtesy Ed Gilman
Ball Moss photo courtesy Ed Gilman
Many "air plants" or epiphytes are also seen at this time of year. Spanish Moss and Ball Moss are native plants closely related to the pineapple. We may see more air plants on weakened or damaged plants because under stress may also have thinner foliage. This allows more light to penetrate into the branches, stimulating the growth of air plants. So, air plants grow faster on stressed trees because the tree is weakened, but are not the cause of poor tree growth.
Trees are not likely be killed by Spanish or Ball moss. If air plants become so thick that they shade the leaves of its host, growth might be slowed down. When a diseased or poorly attached limb with lots of these air plants are heavy with rainwater, the branch could break.
Spanish Moss (Tillandsia usneoides) is a symbol of the South, found hanging from tree limbs, especially live oak and cypress. It is gray when dry and light green when wet and it hangs from tree branches in garlands up to 20 feet long. The small flowers are pale green or blue, and fragrant at night. Stems and leaves are slender and curly, and catch water and nutrients from dust. Spanish moss has no roots, so it is not a parasite of the host tree.
Until the 1960's, Spanish moss was harvested commercially, and tons of it were used for mattress and furniture stuffing. Tiny pests - red bugs or chiggers - may lurk within, waiting to bite the unsuspecting. Microwaving or boiling will rid this material of these pests.
Ball Moss (Tillandsia recurvata) is a gray-green epiphyte found on tree branches or telephone wires. It is often mistaken for a small clump of Spanish Moss. It grows in clumps 6-10" in diameter on most kinds of trees, but seems to be especially fond of live oak. Tiny seeds are blown by the wind until they land on a tree branch. They stick fast and develop root-like attachments to the outside of the bark.
Ball Moss is able to convert nitrogen in air (which is unusable to plants) into a form that plants can use. Except for the beans and peas, most plants cannot do this. So when ball moss falls to the ground and decomposes, it provides fertilizers for other plants.
According to Dr. Richard Wunderland of the
Some of these species are at risk due to habitat destruction and over-collection. Another threat is an introduced insect that chews holes in the base of these epiphytes. This “Evil Weevil” was introduced in 1989. Natural predators are being raised to combat this insect by UF/IFAS reducing the need for insecticides.
Giant Wild Pine photo courtesy Barbra Larson/UF
Southern Needleleaf photo courtesy Shirley Denton
Florida Butterfly Orchid Photo courtesy T. Ann Williams
Wild Orchids can also take up space on tree branches. They don’t have any direct vascular connections to the trees on which they live. The Florida Butterfly Orchid (Encyclia tampensis), grows as a clump of bulbous "grass" on oaks and other plants. The flowers look like small butterflies, about one inch in size. Most of the petals are yellowish, with the bottom part of the flower a white and pink color. This orchid and all native plants should not be taken from the wild without permission.
Several species of ferns can also take up residence on tree branches. The Resurrection Fern (Polypodium polypodioides) can cover Live oaks limbs and sometimes on rocks or dry ground. They creep along the furrows of the bark, and produce 6 inch long fronds. The leaves are gray and curled up when dry, but green when wet and unfurled. Resurrection fern gets its water and nutrients from rain and dust, and causes no harm to the tree that supports it. This little plant is the "miracle plant" sold as a novelty item.
Other visitors to the bark of our trees are numerous kinds of lichens,
organisms composed of both fungi and an alga. The algae give the color and
provide the food for the lichen, while the fungus gives protection and shape for
these unusual plants. These gray, green, red or yellowish patches take up space
on tree limbs and branches, but do not harm the tree in any way. Landscape
perfectionists may find their appearance unappealing, and some persons have been
known to spray a fungicide to discourage them. The
At the base of distressed trees, half mushrooms know as conks can sometimes be seen growing from the trunks or roots. These are fruiting bodies of decomposing fungi, and some can attack a declining tree. Gandoderma fungi are a death sentence for many palms. While other species of this fungus can infect hardwood trees, the tree fungi do not affect palms. The presence of any kind of mushroom at the base of a tree is not a good sign, and experts should be called.
Resurrection Fern photo by Dan Culbert
Lichens photo by Dan Culbert
Gandoderma conk photo by Monica Elliott/UF
placed more information on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.
If you need additional information on these epiphytes, please email us at
firstname.lastname@example.org or call us
at 863-763-6469. Local residents can
stop by our office at 458 Hwy 98 North in Okeechobee, and visit our
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Babcock, Sharon Epiphytes Are Everywhere The Green Thumb St. Lucie County’s Master Gardener Newsletter Volume 1, Issue 9 July, 2004
Christman, Steve Polypodium polypodioides (Resurrection Fern) Floridata Plant Profile. website 10/17/03.
Daniel F. “What’s that in my
ibid. "Kiss Karefully with Mistletoe". Okeechobee: Okeechobee Times and Okeechobee News. 12/2003.
DeValle, Terry. "Killer
Lichens a Myth
Frank, J. Howard, Cave, Ronald,
Hall, Ed and Thomas, Michael
Schubert. T. S. Epiphytic Bromeliads on Florida Trees Plant Pathology Circular 333. Tallahassee: FDACS Division of Plant Industry,1990.