Tropical Soda Apple

How do I identify tropical soda apple? There are several species in the nightshade genus (Solanum) that might be confused with tropical soda apple, but the most common look-a-like is horsenettle  (S. carolinense).  Tropical soda apple looks a bit like horsenettle on steroids – the plants are bigger, the leaves are bigger, the thorns are bigger and the fruit is bigger.  Below are key features to help identify tropical soda apple.

• Form: shallow rooted, spreading, thorny perennial shrub from 3 to 6 feet tall.
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• Leaves: 4 to 6 inches long and 2 to 6 inches wide, shallowly lobed with dense, sticky pubescence (velvety hair) on both sides, large prickles (1/2 to 1 inch) occur along the mid-veins.  Horsenettle leaves tend to be more narrow and the prickles are much smaller and only on veins on the bottom surface of the leaves.

• Flowers:  May to August. Clusters of flowers with five white petals that are straight when first opened then curve back towards the stem, center is yellowish (Figure 1). The petals of horsenettle are fused and range from white to lavender.
  

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• Fruit: June to November.  Round (1-1.5 inches), smooth, mottled white and green (like watermelon rind) when immature (Figure 2), turning yellow when ripe. Occur in the leaf axils. Calyx (green leafy material at the top of the fruit where it attaches to the stem) covers very little of the fruit.  Horsenettle fruit is smaller (~0.5 inches) and the calyx reaches nearly a third of the way down the side of the fruit.
  
  
• Where does it grow?  Tropical soda apple is most commonly found in pastures, but is also found in open woods and other semi-shady areas.  It has been reported in scattered locations across the state and the southeast (Figure 3).  Reporting new locations of tropical soda apple will be very helpful in determining how rapidly it is spreading. Reports can be made using the Early Detection and Distribution Mapping System (http://eddmaps.org) or the free SEEDN app (https://apps.bugwood.org/apps/seedn/) which makes reporting from the field a snap. Reports can be marked private and will not be visible to the general public.

For Horse Nettle see https://www.invasiveplantatlas.org/subject.html?sub=6440

Plant(s); August. Photo from Forest Plants of the Southeast and Their Wildlife Uses by J.H. Miller and K.V. Miller, published by The University of Georgia Press in cooperation with the Southern Weed Science Society. James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org Additional Resolutions & Image Usage	Fruit(s); August. Photo from Forest Plants of the Southeast and Their Wildlife Uses by J.H. Miller and K.V. Miller, published by The University of Georgia Press in cooperation with the Southern Weed Science Society. James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org Additional Resolutions & Image Usage	Fruit(s); Rebekah D. Wallace, University of Georgia, Bugwood.org Additional Resolutions & Image Usage	Foliage; underside of leaf Rebekah D. Wallace, University of Georgia, Bugwood.org Additional Resolutions & Image Usage
Foliage; top of leaf Rebekah D. Wallace, University of Georgia, Bugwood.org Additional Resolutions & Image Usage	Foliage; James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org Additional Resolutions & Image Usage	Fruit(s); James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org Additional Resolutions & Image Usage