Taxonomic name: Solanum tampicense Dunal
Synonyms: Solanum houstonii Dunel 1813, non Martyn 1807, Solanum quercifolium Miller
Common names: ajicón (Cuba), aquatic soda apple (English), espina de manglar (Spanish), huevo de gato (El Salvador), huistomate (El Salvador), salsita de agua (Spanish), scrambling nightshade (English), sosumba (Belize), wetland nightshade (English)
Organism type: shrub
Solanum tampicense is a member of the same genus as the tomato and is native to parts of the Caribbean, Mexico and Central America. In the United States, this shrub has invaded Florida, where it creates impenetrable monocultural stands and climbs over native vegetation in a vine-like fashion. It is found inhabiting cypress swamps and river margins where it spreads most effectively by floating seeds and stem fragments to new locations. S. tampicense is invasive because of its high tolerance to sunlight and shading, ability to handle temporary flooding, and prolific seed production.
S. tampicense is a perennial shrub (USDA-NRCS 2002). According to Ramey and Murray (2001), the flowers of S. tampicense are white and yellow and tomato-like (being in the same botanical genus as edible tomatoes). Its fruits are pea-sized berries, in clusters of up to 11 berries. The berries turn from green to orange to deep red as they ripen with each berry containing 18 - 50 disc-shaped seeds that are 2mm wide. The leaves are elongate (to 8 - 25cm long, 2 - 7cm wide), with indented edges and star-shaped clusters of microscopic hairs. There are straight prickles on the veins on the upper sides of the leaves and curved prickles underneath. Sprawling stems are up to 1cm wide and 2 - 5m long, and they lack hairs but are covered in curved prickles. The prickles snag and interlock so that plants can form impenetrable thickets that can cover over small trees and bushes to a height of 5m (Fox and Bryson 1998).
riparian zones, wetlands
According to FLEPPC (2003), S. tampicense can be found in relatively undisturbed wetlands, typically cypress swamps or along river margins. S. tampicense grows in shade and full sunlight. It is also somewhat flood tolerant. It sheds its leaves in high water then regrows new ones when the flood recedes and while small seedlings may only tolerate a few weeks of submersion, mature plants can recover after several months. However, the shrub is not tolerant of permanent flooding. S. tampicense is susceptible to frost but may re-grow from root crowns.
FLEPPC (2003) explains that S. tampicense is capable of forming large, tangled, monocultural stands of many hectares by invading sparsely vegetated areas or clambering over native vegetation. S. tampicense is able to create these stands because of its high tolerance to sun and shade, tolerance of temporary flooding, prolific seed production, and seed longevity.
Native range: S. tampicense is native to parts of the Caribbean, Mexico and Central America (FLEPPC 2001). It was introduced to the United States and is present in southwestern Florida (USDA-NRCS 2002).
Introduction pathways to new locations
Floating vegetation/debris: Seeds and stem fragments are dispersed downstream by water flows (FLEPPC 2003).
Local dispersal methods
Consumption/excretion: Most species in the Solanum genus are dispersed by birds (FLEPPC 2003) and captive birds will eat the fruit and viable seeds are regurgitated or defecated (Fox pers. comm.)
Preventative measures: The major control method in the USA is prevention.S. tampicense is listed on the Federal Noxious Weed List (USDA-NRCS 2002).
Chemical: Some populations in SW Florida have been successfully controlled using herbicides approved for use in aquatic habitats such as glyphosate, triclopyr and 2,4-D. However, seeds have been shown to survive burial for at least 5 years, so annual surveys and retreatments may be necessary (Fox pers.comm.)
Biological: According to Cuda et al. (2003), S. tampicense “is an ideal target for classical biological control.” This species tends to form extensive impenetrable thickets in remote, periodically flooded areas that make controlling the plant by conventional means a difficult task. Cutting plants back is ineffective for control because they can resprout from the root crown even after several months of submersion in water. Cuda et al. (2003) goes on to state that “field surveys in Florida and in the native range would need to be conducted to discover potential biological control candidates.”
According to FLEPPC (2003), S. tampicense flowers and fruits emerge in May in Florida if subjected to full sunlight or early fall if subjected to full shade. Sunlight also effects seed production, which can be as high as 247 seeds on one stem in full sunlight but less than 10% of that in shade. Plants can be regenerated from any stem sections that are kept wet and have a leaf or leaf-scar with a healthy bud. Plants can regrow from shoots developing from the root crown, an important recovery mechanism after mechanical damage, freezing, herbivory, etc.
S. tampicense seeds are very durable and tolerant of freezing, drying and passage through a bird's gut; they can survive at least 5 years of burial in wetland soil, and fresh seeds have a 90% germination rate (FLEPPC, 2003).
Reviewed by: Alison Fox, University of Florida
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Last Modified: Thursday, 23 March 2006