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Publication #HS1281

Pond Apple—A Tree Species Adapted to Salt Stress1

Guodong Liu, Yuncong Li, Kimberly Moore, and Kim Gabel 2

Soil salinity is a naturally occurring problem for growers, gardeners, and homeowners in Florida. As sea-levels rise, seawater intrusion causes salt stress to plants grown in coastal lowland areas. The current practices for reducing salt stress are chemical strategies like oxygen fertilization and are only temporary solutions (Liu et al. 2016). The long-term approach must be a biological strategy that involves incorporating plant species that are adapted to salt stress. This article introduces a salt-tolerant species, pond apple (Annona glabra L.), which has great potential to be used in high-salinity coastal landscapes.

Pond apple is a member of the custard apple family, Annonaceae. Figure 1 presents a photo of young pond apple plants. More photos of the pond apple can be found at http://lee.ifas.ufl.edu/Hort/GardenPubsAZ/Pond_Apple.pdf. Pond apple is also called bobwood, corkwood, monkey apple, swamp apple, or alligator apple because American alligators often eat the fruit (Standley 1922). Feral pigs and other wild animals, including cassowaries, also consume this fruit, and the seeds are dispersed over great distances in their droppings (Natural Heritage Trust 2003).

Figure 1. 

Pond apple seedlings.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Pond apple, a semi-deciduous, woody tree, is native to mainland Florida. The Institute of Regional Conservation lists this species as a native species in south Florida (Gann et al. 2016). The USDA map of pond apple locations shows that this species is distributed only in Florida and Puerto Rico (http://plants.usda.gov/core/profile?symbol=ANGL4). The species can grow 10 feet or taller. The plant has alternate leaves with an acute tip of 3–6 inches long and 1.5–2.5 inches wide with a prominent midrib. The leaves are light or dark green on the upper surface and paler on the underside. The flowers are white to light yellow, approximately 1 inch in diameter. They have six petals including three leathery ones outside and three smaller ones inside. The inner base of the flower is red. This species can bear fruit starting at two years. The fruit is edible and looks like a custard apple. The fruit size is similar to a mango, ranging from 2 to 6 inches. The fruit contains approximately 100 seeds resembling pumpkin seeds in both appearance and size (Natural Heritage Trust 2003). The fruit of this species was an important food source for the early Native Americans and settlers. The fruit can be eaten raw, boiled, or made into jellies (Morton 1974; Allen et al. 2012). Seeds, bark, and leaves of this plant contain many potent chemicals including some of the alkaloids found in opium (Morais et al. 1998), polyketide natural products (Bermejo et al. 2005), and activators of dopamine receptors (Millan et al. 2002). They can all be used pharmaceutically or medically (Austin 2001). Recent research suggests that pond apple plant extracts contain anticancer chemicals (Cochrane et al. 2008).

Pond apple and bald cypress [Taxodium distichum (L.) Rich] both grow well in flooding conditions such as in the Everglades. Their leaf morphology and water relations, however, are totally different. Pond apple’s broad leaves have a thick wax layer on either the upper or under surface and have low transpiration rates. In contrast, bald cypress has a significantly smaller leaf area and a thin wax layer on both surfaces. The differing leaf morphology and the underlying physiological differences may be the mechanisms to make pond apple significantly more tolerant to salt stress than bald cypress (Figures 2 and 3).

Figure 2. 

Bald cypress and Pond apple seedlings grown in saltwater containing 15, 000 ppm sodium chloride (NaCl). A. bald cypress seedlings, 0 roots submerged but irrigated with the saltwater, survived. B. bald cypress seedlings, 100% roots submerged with the saltwater, 100% died 9 days after being treated. C. pond apple seedlings, 100% roots submerged with the saltwater, 100% growing. D. pond apple seedlings, 0 roots submerged but irrigated with the saltwater, 100% growing.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Figure 3. 

Bald cypress seedlings (left two plants) died of salt stress after roots were 100% submerged in brackish water with 15, 000 ppm sodium chloride for 9 days, while pond apple seedlings (right two plants) grow well in the same growth condition.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Pond apple is very tolerant to brackish water conditions but sensitive to low-iron stress. When this species is grown in dry conditions, the leaves turn yellow easily and rapidly due to iron deficiency (Figure 4). Thus, this species needs to be grown in soil with appropriate moisture. If the leaves turn yellow, iron fertilization is needed. To avoid or correct iron deficiency of the species, please read these EDIS publications on iron: Irony Deficiency in Palms (http://edis.ifas.ufl.edu/ep265), Iron (Fe) Nutrition in Plants (http://edis.ifas.ufl.edu/ss555), Understanding and Applying Chelated Fertilizers Effectively Based on Soil pH (http://edis.ifas.ufl.edu/hs1208) (Broschat 2011; Hochmuth 2014; Liu et al. 2015).

Figure 4. 

Pond apple seedlings suffering from iron deficiency.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

References

Allen, G. M., M. D. Bond, and M. B. Main. 2012. 50 Common Native Plants Important in Florida’s Ethnobotanical History. Cir 1439. Gainesville: University of Florida Institute of Food and Agricultural Sciences. Accessed April 19, 2016. https://edis.ifas.ufl.edu/pdffiles/UW/UW15200.pdf

Austin, D. 2001. “Pond Apples.” The Palmetto 21(1): 10–11. Accessed May 1, 2016. http://www.fnps.org/assets/pdf/palmetto/austin_dr_dan_pond_apples_no_4_people__plant_interaction_series_discovering_fls_ethnobotany_vol_21_no_1_november_2001.pdf

Bermejo, A., B. Figadère, M.-C. Zafra-Polo, I. Barrachina, E. Estornell, D. Cortes. 2005. “Acetogenins from Annonaceae: Recent Progress in Isolation, Synthesis and Mechanisms of Action.” Natural Product Reports 22(2): 269–303.

Broschat, T.K. 2011. Iron Deficiency in Palms. ENH 1013. Gainesville: University of Florida Institute of Food and Agricultural Sciences. Accessed April 19, 2016. http://edis.ifas.ufl.edu/ep265

Brown, S.H. and S. Mark. 2013. Annona glabra. Fact Sheet. UF/IFAS and Lee County Extension. Accessed May 1, 2016. http://lee.ifas.ufl.edu/Hort/GardenPubsAZ/Pond_Apple.pdf

Cochrane, C.B., P.K. Nair, S.J. Melnick, A.P. Resek, C. Ramachandran. 2008. “Anticancer effects of Annona glabra plant extracts in human leukemia cell lines.” Anticancer Research 28(2A): 965–71.

Gann, G.D., M.E. Abdo, J.W. Gann, G.D. Gann, Sr., S.W. Woodmansee, K.A. Bradley, E. Grahl and K.N. Hines. 2016. "Natives for your neighborhood: a program of the Institute for Reginal Conservation." Accessed April 19, 2016. http://www.regionalconservation.org/beta/nfyn/plantdetail.asp?tx=Annoglab

Hochmuth, G. 2014. Iron (Fe) nutrition in plants. SL 353. Gainesville: University of Florida Institute of Food and Agricultural Sciences. Accessed April 19, 2016. https://edis.ifas.ufl.edu/ss555

Liu, G.D., E. Hanlon, and Y.C. Li. 2015. Understanding and Applying Chelated Fertilizers Effectively Based on Soil pH. HOS 1280. Gainesville: University of Florida Institute of Food and Agricultural Sciences. Accessed May 1, 2016. http://edis.ifas.ufl.edu/hs1208

Liu, G.D., Y.C. Li, K. Moore, K. Gabel, L. Wu, and R. Muñoz-Carpena. 2016. How to Chemigate Salinity-Stressed Plants with Hydrogen Peroxide to Increase Survival and Growth Rates. HOS 1280. Gainesville: University of Florida Institute of Food and Agricultural Sciences.

Millan, M.J., L. Maiofiss, D. Cussac, V. Audinot, J.A. Boutin, A. Newman-Tancredi. 2002. “Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. I. A multivariate analysis of the binding profiles of 14 drugs at 21 native and cloned human receptor subtypes.” The Journal of Pharmacology and Experimental Therapeutics 303(2): 791–804.Accessed April 19, 2016. http://jpet.aspetjournals.org/content/303/2/791

Morais, L. C. S. L., J. M. Barbosa-Filho, R. N. Almeida. 1998. “Central depressant effects of reticuline extracted from Ocotea duckei in rats and mice.” Journal of Ethnopharmacology 62 (1): 57–61. Accessed April 19, 2016. http://www.sciencedirect.com/science/article/pii/S0378874198000440?np=y

Morton, J. 1974. 500 Plants of South Florida. E.A. Seemann Publishing, Inc., Miami, FL. 163 pp.

Natural Heritage Trust. 2003. “Pond Apple (Annona glabra L.).” Weed Management Guide. ISBN 1-920932-13-5. http://www.lrm.nt.gov.au/__data/assets/pdf_file/0019/5257/pond_apple_mgt_guide.pdf

Standley, P. C. 1922. "Trees and Shrubs of Mexico". United States National Herbarium 23(2): 281–282

Footnotes

1.

This document is HS1281, one of a series of the Horticultural Sciences Department, UF/IFAS Extension. Original publication date April 2016. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Guodong Liu, assistant professor, Horticultural Science Department; Yuncong Li, professor, Department of Soil and Water Sciences, Tropical Research and Education Center; Kimberly Moore, professor, Environmental Horticulture Department, Fort Lauderdale Research and Education Center; Kim Gabel, Environmental Horticulture Agent, Monroe County Extension. UF/IFAS Extension.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.