UF/IFAS
Okeechobee County Extension Service
458 Highway 98 North
Okeechobee, FL 34972-2578
Phone: (863) 763-6469
E- mail: indianco@ufl.edu
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September 28, 2005
Feature Article - for release the week of October 2, 2005
Dan Culbert - Extension Horticulture Agent
The Weed with Two Leaves
Twice last week some office visitors brought in samples from an unknown plant for our Master Gardeners to identify. Besides having distinctive yellow berries, it had a curious arrangement of having two unequal sized leaves that grew from each bud. According to UF Extension Weed Specialist Dr. Ken Langeland, Twin-leaved Solanum is one of the new “featured fiends” that will be included in his new second book of Florida’s invasive plants.
This plant is cropping up in more and more Florida Yards all over the southern part of the peninsula, and is worth removing from your landscape as soon as it is noticed. If it is allowed to drop its berries, expect to be picking the seedlings from around your landscape shrubs and trees for years to come.
While it is not as invasive as the infamous Brazilian Pepper tree, it has the potential to invade natural areas as well as become a persistent landscape weed. The UF/IFAS Task Force on Invasive species cautions its use as an ornamental because of its ability to spread, and the Florida Exotic Plant Pest Council has added it to its Group II list – those plants that have the ability to spread into natural areas if conditions are favorable.
Twin-leaved Solanum or Two-leaved Solanum (Solanum diphyllum) is a native of Mexico and Central America. Another name sometimes given to this plant is Amatillo, which is the name of places in El Salvador, Guatemala & Honduras. (There is also a town of Amatillo in Texas, where this weed has also escaped cultivation.)
Leaves of this plant are generally a deep green color and smooth, and can measure 1 to three inches long. The pairs of leaves grow with one big and one small leaf. The plant itself forms an upright woody stem that can grow up to 6 feet in height, but they more typically top out at three to four feet.
Twin-leaved Solanum flowers look very
similar to those of eggplants and peppers, which are relatives of this
weed. Photo courtesy of Matthew
Merritt |
Mature Amatillo plants show the two different sized leaves and have
lots of yellow "cherry-tomato" sized berries. Photo
by Dan Culbert |
|
Current Florida range
of Twin-leafed Solanum. Graphic
Courtesy During warmer months it will produce clusters of small white five-petaled flowers that give rise to the round yellow berries. The fruit can be one-half inch in diameter, and are filled with many black seed. They remind me of small cherry tomatoes with hardened skin. No doubt that many others see this as well, as they are very closely related to tomatoes, peppers, and other members of the nightshade family.
According to Dr. Langeland, the plants may freeze back in winter but will resprout from their roots. Research shows that 75-85% of the seed will sprout, and the seed can stay alive even when buried an inch in the soil for up to two years. Birds and bats will also help spread this plant by eating the fruit and depositing them elsewhere.
Last year I was walking through the Mexico pavilion at EPCOT, in the Disney property, and saw this upright woody bush growing in the landscape between the tropical Hibiscus and Philodendrons. I also saw one growing next to a neighbor’s bougainvillea vine, and the resulting fruit easily spread many seedlings into my yard. Have you seen them in your neighborhood?
|
Look carefully between the Hibiscus and Philodendron - no place is immune from the invasion of this plant - even Disney's Horticulture staff has to keep an eye out for this invader. Photo by Dan Culbert |
Records are unclear as to when it came to our area, but it was grown as an ornamental plant in the 1960’s. At one time was available for sale in Florida nurseries. Because it is so easily grown from seed, and escapes into the landscape, there is no commercial market for this plant as an ornamental. In 2001 the Florida Nursery Growers and Landscapers Association recommended that this species no longer be propagated, sold or used in Florida.
One office visitor wanted to know if this plant was poisonous. I was not able to find any information about poisonous qualities occurring with twin-leaf Solanum, but since many of this plant’s relatives contain highly toxic constituents, I’d not recommend it as an edible plant.
The best way to keep this invader from your Florida Yard is to become familiar with what it looks like, and pull the small plants out before the berries are formed. We don’t have any specific recommendations for chemicals that will selectively remove Amatillo from your landscapes, but if herbicides are desired, a carefully directed application of a nonselective weed killer like glyphosate will discourage the seedlings. Remember to read and follow all label directions on any pesticide.
I’ve placed more information on our Okeechobee web page, http://okeechobee.ifas.ufl.edu. If you need additional information on Twin-leaved Solanum, 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 on Tuesday afternoons from 1 to 5 PM.
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Millie
Ferrer Chancy, Interim Dean Last update: 07/20/2010
. This page is maintained
by Dan Culbert
Cherry, H. M., McCormick, C. M., Langeland, K. A., and Burks, K. Craddock. Identification and Biology of Non-Native Plants, 2nd Edition. [tentative title]. Gainesville: UF/IFAS Florida Cooperative Extension Service. In preparation.
Markle, L. T., Overholt W. A. and Langeland, K. A.. Natural Area Weeds: Invasive Solanum spp. in Florida [SS AGR 312]. Gainesville: UF/IFAS Florida Cooperative Extension Service, 12/2008.
Vandaveer,
C. Plant of the Week for November 8, 2004. Largo: Killerplants.com
website. http://www.killerplants.com/plant-of-the-week/20041108.asp
Whitinger, Dave.
Wunderland, Richard. Solanum diphyllum . Tampa: University of South Florida, Institute for Systemic Botany, Atlas of Florida Vascular Plants, 2005. http://www.plantatlas.usf.edu/main.asp?plantID=1760