September 6, 2006

Feature Article - for release the week of September 10, 2006

Dan Culbert - Extension Horticulture Agent 

Quick Links:   Names   Description    Invasiveness   References

 

  Beware the Bolivians  

An issue that has come into national attention has been the “invasion” of our country by aliens. It’s riled up folks all across the border and has now begun to pop up as an issue in our local neighborhood.  But the USA is not the only place where these invaders are becoming an issue.

It’s those darn Bolivian Sunflowers that were talking about today – a tall clumping bush with typical daisy flowers.  This plant is a tall thick-stemmed plant that is topped with lots of attractive yellow flowers.  Often planted as a screening plant, they can thrive in our climate year round, and have the potential to spread into unwanted areas.  

A Sunflower with lots of names

To be fair, this ornamental plant is known by several common names.  This plant has also been called Mexican Sunflower, Honduras Sunflower, Japanese Sunflower, and Shrub Sunflower.  Tree Marigold is another suitable common name, and I won’t go into some of the many other foreign language names that I’ve dug up. 

With all these confusing names, it’s a good chance to show the “beauty” of botanical names: Tithonia diversifolia is a name that will work for both gardeners in Okeechobee and botanists from Queensland.  I’m told the first part of the name came from a legend: a Trojan named Tithonus was loved by the dawn goddess Eos, but she tired of him and turned him into a grasshopper.  The species name tells us that the leaves of this plant have several different shapes. (And you just thought all that scientific name stuff was just a bunch of Greek, right?)

As the common names suggest, this is a native of the Central America and Mexico.  It is cultivated for its beautiful flowers and enormous size.  It’s a member of the Daisy family, and is related to the orange-flowered Tithonia rotundiflora, which is also known as the Mexican Sunflower, a totally different plant.  

 

Big Clumps of Yellow Daisies

Leaves of this plant may have different shapes, and some will have deep lobes. (Different foliage = diversifolia.)  Photo: UCLA Mildred E. Mathias Botanical Garden

Bolivian Sunflower produces many large yellow flowers:  Photo: B. Navez

Flowers of Tithonia diversifolia look like sunflowers.  They are about 6 to 7 inches across.  Photo: Bob Bierman, Plant Atlas of FL

 

Given a year or two, one small branch can quickly grow from 8 to15 feet tall, and spread to a 6-foot wide clump.  Its fast growth, upright habit and colorful flowers have made it a seemingly popular choice for an instant screening plant. 

The six to seven inch bright golden daisy of the Bolivian Sunflower is not a single flower, but is a head made up of many small flowers. Around the rim are eleven to thirteen rays that have the bright “petals”.  Inside the floral circle are 200 to 300 tubular florets, each one able to form a seed.  Because of their small size, the seed can easily be spread by wind, further increasing the range of this plant.  

The flower fragrance of our alien has been described by some as smelling like chocolate, while others say it has a honey-like aroma.  In our area, Tithonia can bloom from late spring until the late fall.  The plant's flowers are visited by butterflies and many bees, so some refer to this as a plant that encourages wildlife – an argument that I disagree with.

The deep leaves of this Tree Marigold are large and have a fuzzy texture.  The larger leaves are deeply lobed.  As the plant gets taller it will form a rangy shrub with wide pithy, unbranched stems that are leafless at their lower heights.  It is suggested that this plant be cut back to one foot tall after the blooming period to help control the height and width of the clump.

In Africa, this species has been used as a “natural” pesticide.  Farmers make a tea from either burnt or fresh leaves and apply it to termite infested affected trees or directly on mounds to provide a limited period of protection from these insects.  The large size of the plant has interested some farmers in Columbia as a biomass plant to add organic material to poor soil and as a feed source for some livestock. 

 

An Invasion from the South

I can attest to its rapid rate of growth.  When visiting a nursery about 10 years ago, the grower gave me a foot-long one-inch thick stem section that had a few roots.  I potted it up, and away it grew.  When it reached a height of about 4 feet, I transplanted it along a fence in my back yard.  As it grew taller, some of the stems fell over the fence.  They rooted, formed new plants and continued their spread into a pepper infested power line easement. 

This thicket continued to take over until the 2004 and 2005 hurricanes knocked it all down.  It has since recovered well, and the new growth is back as thick as it ever was.   And now seedlings have begun to spread down wind of the original site.  Applications of nonselective herbicides like glyphosate have been used to rid areas of these volunteers as they attempt to take over natural areas.

I highly recommend that homeowners be careful if this plant is introduced into your Florida Yard.  Frost free areas may see it take hold and invade places where it can crowd out desirable native habitat.  We don’t need any more of these kinds of aliens in our piece of paradise. (Note: at this time, this plant has not yet been assessed by the UF/IFAS Invasive Plant Task Force.)

I’ve placed photos and more information on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on the identification or management of Bolivian Sunflower, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners.  

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Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Millie Ferrer-Chancy, Interim Dean Last update: 04/11/2011 .  This page is maintained by Dan Culbert 

 

references

Chuba, D.K. and Muoghalu, J. I.  Seed Germination and Reproductive Strategies of Tithonia diversifolia and  T. rotundifolia.  Lusaka, Zambia: University Of Zambia, June 2005.  http://www.ecology.kee.hu/pdf/0301_039046.pdf#search=%22Tithonia%20diversifolia%22

Erdek, Paul. Tithonia diversifolia. (Plant of the Month). Florida Gardener.com, 8/1/04.  http://www.floridagardener.com/pom/tithonia.htm      

Everett, T.H.   NYBG Illustrated Encyclopedia of Horticulture  p. 3357.    New York Botanical Garden, 1982.  

Mildred E. Mathias Botanical Garden.  Tithonia diversifolia. Los  Angeles:UCLA. In (MEMBG) Newsletter,  Winter 1999, Volume 2(1) http://www.botgard.ucla.edu/html/MEMBGNewsletter/Volume2number1/Tithonia.html

Space, Jim. Tithonia diversifolia (PIER species account)  Hawaii: Pacific Island Ecosystems at Risk (PIER), 11/14/05. http://www.hear.org/pier/species/tithonia_diversifolia.htm 

Starnes, John A. "As good as gold Plant is jack-of-all-trades."  St. Petersburg Times, November 11, 2006.  http://www.sptimes.com/2006/11/11/news_pf/Homes/As_good_as_gold_Plant.shtml 

Gulf Frilitary Butterfly on Bolivian Sunflower (c) Judson Rhodes

Eos ("Dawn") pursuing Tithonus, Attic red-figure oinochoa by the Achilles Painter, ca. 470 BC–460 BC, found in Vulci. Location: Louvre, Department of Greek, Etruscan and Roman Antiquities, Sully wing, Campana Gallery (MA 343) Photographer: Jastrow (2006)

Want more Photos?  Click on this picture!