Tropical Plants in Your Backyard

Above: Northern spicebush flowers. Credit: Drew Chaney

By David Bellangue, Nursery Manager, Piedmont Discovery Center

As I sit by my computer, I glance out the window at the cold landscape outside. Trees bare of leaves stand like solemn sentinels against an overcast sky that looks down on a drab world of grays and browns. You can almost feel the chill just by looking out the window, and I dream of a winter getaway in some tropical land filled with all manner of strange and wonderful plants that would never survive winter in temperate North America. 

Sadly, a tropical escape is not possible, and I turn my thoughts towards some botanical wonders awaiting springtime with me in my own backyard. As it would happen, tropical flora is closer than you might think as several members of our temperate flora belong to plant families much more at home in the warmth of tropical forests than the temperate woodlands and forests of Virginia. The three species highlighted in this post (pawpaw, northern spicebush, and American persimmon) are the northernmost members of their respective families (Annonaceae, Lauraceae, and Ebenaceae). In this post, you will be treated to a brief overview of these tropical families including their origins, main distribution today, and economically important species and genera, as well as descriptions of their temperate members that are found throughout Virginia. Without further ado, let’s explore the tropical plants that are at home in our own backyard! 

Annonaceae (Custard-apple Family)

Botanical illustrations for sweetsop (Annona squamosa) & soursop (Annona muricata) from Fleurs, fruits et feuillages choisis de l’ille de Java: peints d’après nature, published in 1880. Credit: Swallowtail Garden Seed, Flickr.

Familial Characteristics: Tree, shrub, or woody vine with aromatic plant parts bearing simple (not divided into leaflets), entire (smooth around the edge of the leaf) leaves arranged alternately in two rows up the stem. Flowers radially symmetrical, usually with 3 sepals and 6 petals and numerous stamens arranged into a ball-like configuration. Flowers are pollinated by beetles or flies, as this family arose before the evolution of bees. Fruit an aggregate of berries (fleshy fruit with more than one seed).  

Origin: Earliest fossil evidence for the family comes from fossilized pollen, putting the origin of the family between 89 to 91 million years ago (Takahashi et al. 2008). The family spread throughout the tropics during this time from a combination of rafting on drifting land masses and long-distance dispersal events (Couvreur et al. 2011). It is one of the earliest flowering plant families to develop. 

Main distribution and center of diversity: Throughout the tropical and subtropical regions of the world. Characteristic of lowland tropical wet forests. Highest diversity of species are found in the Neotropical realm of South and Central America with around 900 species (Judd et al. 2016).

Genera/species: 128/2,300

Economically important members: Edible fruit from Annona like sweetsop (A. squamosa), cherimoya (A. cherimola), soursop (A. muricata), and Asimina (pawpaw). Perfumes from Cananga odorata (ylang-ylang). Several genera (Annona, Cananga, and Monoon) cultivated as ornamentals (Judd et al. 2016). 

Locally Native Representative: Pawpaw (Asimina triloba)

Pawpaw flower and leaves in spring. Photo credit: Ezra Staengl

Of the 8 species in the genus Asimina, most are confined to Florida and adjacent states with several species listed as endangered there. Two are found in Virginia (A. triloba & A. parviflora), but only the common pawpaw is widespread.

Name: Asimina ; a Latinized version of a gallicized (French in character) indigenous name for the fruit; triloba for the three lobed flowers. 

Clockwise from top left: Pawpaw flowers, leaves, twig, and fruit.

ID: Deciduous shrub or tree up to 15 m (50 ft) with light brown smooth bark. Leaves simple and entire born alternately along the stem, broadest above the middle. When crushed, leaves emit a strong odor likened to that of a bell pepper (Swanson 1994). Terminal bud is large, elongated, and flattened without a covering, reddish or dark brown and wooly. Flower buds visible all winter long as fuzzy brown spheres. Flowers, dark purple to brown 2.5-4 cm (1-1.5 in) wide with six petals, appear with the leaves in the spring. Large edible kidney-shaped berries with sweet yellow pulp (yellowish green to brown in color) mature late in the summer in clusters. 

Habitat: Well-drained floodplain forests, mesic to occasionally dry upland forests, wet flatwoods, and swamps. Occurring most abundantly on base-rich soil. Common in the Coastal plain and Piedmont, somewhat common at lower elevations in the Mountains (Weakly et al. 2020).

Blooming season: March to May

Fruit Season: Late August to early October

Fun Facts: 

  • Largest fruit native to North America that evolved for megafaunal dispersal(a niche that was filled by people after the megafauna went extinct). Native American cultivation contributed to pawpaw’s expansive range (Hormaza 2014;USDA & NRCS 2024). 
  • Various chemical compounds produced by pawpaws are under investigation for use, especially for cancer-fighting properties (McLaughlin 2008). 
  • Pawpaws serve as the host plant for the zebra swallowtail butterfly (Eurytides marcellus).

Lauraceae (Laurel Family)

A selection of economically important Lauraceae members including Java cinnamon (Cinnamomum javanicum) top right; sweet bay (Laurus nobilis) top left; and avocado (Persea americana) bottom. Photo credit: Illustrations of the Natural Orders of Plants (Twining & Rougeux)

Family Characteristics: Tree, shrub, or occasionally parasitic vine (genus Cassytha). Often evergreen. Leaves most often alternately arranged, simple, entire (though rarely lobed), and with clearly visible leaf veins; often contain aromatic oils. Flowers bisexual (complete) or unisexual (dioecious), usually small pale green, white, or yellow with 3-12 stamens.  Fruit most often a drupe (fleshy fruit with a single seed or pit).  

Origins: One of the first flowering plant families to evolve during the Early to Middle Cretaceous (around 113 and 100 million years ago) (Balthazar et al. 2007). In that time, Lauraceae spread across many regions and diversified rapidly. With the breakup of the supercontinents Gondwana and Laurasia, many laurel ancestors drifted with the newly created land masses, resulting in widespread distribution in the face of extensive geographic barriers (like oceans, deserts, and high mountains).   

Main Distribution & Center of Diversity: Widespread in tropical and subtropical regions of the world with few members extending into temperate regions. Particularly diverse in Southeast Asia and northern South America. 

Genera/species: 50/2,500 

Economically important members: Several members are important spice plants including Laurus nobilis (bay leaves), Cinnamomum verum (cinnamon), and Sassafras albidum (sassafras). Persea americana (avocado) is an important tropical fruit tree and several members are used for perfume production and as timber. 

Northern spicebush branch with ripe fruit Photo credit: Tom Potterfield, Flickr.

Locally Native Representative: Northern spicebush (Lindera benzoin)

The genus Lindera contains between 80-100 species mostly occurring in East Asia. 3 members occur in North America and only the northern spicebush is abundant and widespread in Virginia. 

Name: Lindera honors Swedish botanist and physician Johann Linder (1676-1723); benzoin comes from Arabic vernacular meaning aromatic gum (Missouri Botanical Garden 2023).

Clockwise from top left: Northern spicebush flowers, buds, fruit, winter fruit, and trunk.

ID: Deciduous, upright aromatic shrub 1-5 m (3-16 ft) bearing obovate (egg-shaped narrowing towards the base) to oblong (longer than wide) simple, entire leaves glabrous or nearly so (lacking hairs) alternately arranged up the stem with leaf size decreasing towards the base of twig. Twigs greenish to greenish brown in color. Trunk and branches are covered in many lenticels (small openings that allow for gas exchange). Plants are dioecious with male and female flowers occurring on separate plants. Flowers are somewhat inconspicuous, up to 7 mm (0.276 in) wide, yellow in color, and bloom before foliage develops in the early spring (flower buds are often visible from fall through late winter). All plant parts emit a fragrant aroma when crushed or scratched. Fruits are small bright red drupes that can persist throughout the winter. 

Habitat: Mesic to dry-mesic upland forests, well-drained floodplain forests, seepage swamps, alluvial swamps, and tidal swamps. Most abundant on base-rich soils. Common throughout Virginia.

Blooming Season: March to April

Fruit Season: August to September 

Fun Facts: 

  • This species and fellow Lauraceae member sassafras (Sassafras albidum) are the larval host plants for the spicebush swallowtail (Papilio troilus). 
  • Over 20 species of birds including wood thrush, hermit thrush, veery, red-eyed vireo, and gray catbird utilize the red berries borne in late summer as fuel during migration. 
  • Its aromatic berries, leaves, and twigs have been used as tea and spice for hundreds of years, lending it another common name – Appalachian allspice. 

Ebenaceae (Ebony family)

Illustrations of representatives from the Ebony family including Malabar ebony (Diospyros malabarica) center; date-plum (Diospyros lotus) bottom left; and cape ebony (Diospyros pallens) right. Photo credit: Illustrations of the Natural Orders of Plants (Twining & Rougeux)

Family Characteristics: Tree or shrub with black or dark colored tissues. Alternate, simple, entire leaves usually with nectar glands on the underside of the leaf. Most usually dioecious flowers, small, with 3-7 petals fused into an urn-like shape. Fruit a berry. Astringent (drying, puckering, or numbing mouth feel) until very ripe, with fairly large seeds. 

Origins: Potentially evolved during the Cretaceous period (145 to 66 million years ago) in western Gondwana and spread to Eurasia and North America into the Paleocene (65 to 56 million years ago). Although, due to variable leaf morphology, attributing fossils to Ebenaceae has been tricky (Wallnofer 2001).

Main Distribution & Center of Diversity: Distributed across most of the tropical and subtropical regions of the planet with a few members extending into temperate regions. Particularly important floristic component in African forests and the Mascarene Islands (Mauritius, Réunion, and Rodrigues) (Judd et al. 2016).

Genera/species: 4/500 with the genus Diospyros (480 species) making up the bulk of the family.

Economically important members: Several members of the genus Diospyros such as black saopte (D. digyna), Japanese persimmon (D. kaki), date plum (D. lotus), and American persimmon (D. virginiana), have edible fruit and many species have been heavily exploited for timber due to their hard dark wood, especially Ceylon ebony (D. ebenum) and Mauritian ebony (D. tessellaria). 

Locally Native Representative: Common persimmon (Diospyros virginiana)

Developing fruit on a female persimmon tree. Photo credit: John Ruter, University of Georgia, Bugwood.org

Of the 480 species in the genus Diospyros, only 2 species grow in the continental US: the Texas persimmon (D. texana), which is confined to Texas, and American persimmon (D. virginiana), which is widespread across the Southeastern US.

Name: Diospyros from the Greek words dios, meaning divine, and pyros, meaning wheat or grain. Literally a divine food or divine fruit. Virginiana means “of Virginia” (Bayton 2020).  

Clockwise from top left: Persimmon leaves, bark, flowers, seeds, and fruit. Credit: Rebekah D. Wallace, University of Georgia, Bugwood.org; CUH

ID: Small to medium-sized tree with dark brown to black bark, that on older plants is deeply divided into small, squarish blocks. Leaves 3-7 cm (1.2-2.7 in) wide and 6-16 cm (2.4-6.3 in) long, elliptical or oblong (mostly rounded at the base with parallel sides), deciduous, simple, and entire, arranged alternately along the stem. Twigs lack terminal buds; lateral buds 2-4 mm (0.079-0.157 in) long, pointed, dark reddish brown to purplish in color. Plant dioecious with female trees bearing solitary urn-shaped flowers that will develop into an edible, fleshy, plum-like berry, orange to yellowish brown in color.    

Habitat: Old fields, fencerows, and roadsides. Found in a range of natural habitats including swamp forests, depressional ponds, dune woodlands, and scrub rocky woodlands, as well as in the understory of mesic to dry deciduous upland forests. In Virginia, commonly found in the Coastal Plains and Piedmont, infrequent and confined to lower elevations in the Mountains. 

Blooming Season: May to June

Fruit Season: September to December

Fun Facts :

  • Fruits are incredibly astringent and best eaten when fully ripe and after the first hard frost. Fruit can be eaten raw or used in syrups, jellies, baked goods, and fruit leather (NC extension Plant Tool Box). Persimmon seeds can be dried, roasted, and ground as a coffee substitute. 
  • Fruit eaten by a wide range of wildlife including raccoons, turkeys, coyotes, and various birds (quail, wild turkey, cedar waxwing, and catbird) (USDA & NRCS 2024).
  • Flowers are an important source of nectar for both native and honey bees. 

Plant Adaptations to the Cold

Given their tropical affinities, how do these three species not only survive, but thrive, across temperate North America? Cold frost, and below-freezing temperatures pose a serious threat to plants. Freezing conditions, especially during the daytime, limit the ability of plants to photosynthesize. Ice crystal growth within plant cells can rupture the cell wall resulting in cell death. Freezing also locks away water in the form of ice leading to dehydration and death, especially when coupled with windy conditions that dry out plant tissues (Rebetez et al. 2004). 

In the face of these limits, woody plants in temperate regions have several strategies to thrive in cold climates. Since even cold-adapted plants are vulnerable to freezing temperatures while actively growing, as day length shortens and temperatures cool plants harden themselves against freeze damage by slowing growth and entering a dormant state until it warms again in the spring. For deciduous species, this means dropping succulent leaves that are easily damaged by frost and prone to drying out, and replacing them with relatively resistant dormant buds. Other strategies include the production of antifreeze chemicals that reduce ice damage to cells and reduction of water in cells to reduce the freezing point in a process called supercooling (Larcher 2005). 

To guard against premature growth during a winter warm spell, temperate plants must experience a certain number of chill hours (exposure to temperatures between 32 and 45 degrees F) before they can resume growth (Körner 2016). Once chill hours are satisfied, plants become more sensitive to other environmental cues, like increasing day length and increasing temperatures as late winter gives way to spring, spurring them to emerge from dormancy. While some plants are more tolerant of lower temperatures, and can start growth at relatively low temperature, others (like pawpaw) wait well into spring before emerging from dormancy to avoid damaging late frosts. 

Sources 

Balthazar, M.V, Pe (2007) Potomacanthus lobatus gen. et sp. nov., a new flower of probable Lauraceae from the early cretaceous (Early to Middle Albian) of Eastern North America. American Journal of Botany.

Bayton, R. (2020). The gardener’s botanical : an encyclopedia of latin plant names. Princeton University Press.

Couvreur, T. L. P., Pirie, M. D., Chatrou, L. W., Saunders, R. M. K., Su, Y. C. F., Richardson, J. E., & Erkens, R. H. J. (2011). Early evolutionary history of the flowering plant family annonaceae: steady diversification and boreotropical geodispersal. Journal of Biogeography, 38(4), 664–680. https://doi.org/10.1111/j.1365-2699.2010.02434.x

Judd, W.S, Campbell, C.S, Kellogg, E.A, Stevens, P.F, & Donoghue, M.J, (2016). Plant Systematics: A Phylogenetic Approach. (4th ed.) Sinauer Associates Inc.

Diospyros virginiana (American Persimmon, Common Persimmon) | North Carolina Extension Gardener Plant Toolbox. (n.d.). https://plants.ces.ncsu.edu/plants/diospyros-virginiana/ 

Hormaza, J. I. (2014). The pawpaw, a forgotten north american fruit tree. Arnoldia, 72(1), 13–23.

Körner, C. (2016). Plant adaptation to cold climates. F1000research, 5. 

McLaughlin, J. L. (2008). Paw Paw and cancer: annonaceous acetogenins from discovery to commercial products. Journal of Natural Products 71: 1311–1321.

Missouri Botanical Garden. (n.d.). Plant Finder: Lindera Benzoin. Lindera benzoin – Plant Finder. https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=d890 

Rebetez Forests, Tree Physiology and Climate in Burley, J., Youngquist, J., & Evans, J. (2004). Encyclopedia of forest sciences (1st ed.). Elsevier.

Swanson, R.E, (1994) A Field Guide to the Trees and Shrubs of the Southern Appalachians, The John Hopkins University Press.

Takahashi, M., Friis, E. M., Uesugi, K., Suzuki, Y., & Crane, P. R. (2008). Floral evidence of annonaceae from the late cretaceous of japan. International Journal of Plant Sciences, 169(7), 908–917. https://doi.org/10.1086/589693

Twining, E. & Rougeux, N. Ebenaceæ, The Ebony Tribe. (n.d.). Orders of Plants. https://www.c82.net/twining/plants/?id=88 

Twining, E. & Rougeux, N. Lauraceæ, The Laurel Tribe. (n.d.). Orders of Plants. https://www.c82.net/twining/plants/?id=116 

USDA, NRCS. 2024. The PLANTS Database (http://plants.usda.gov, 01/04/2024). National Plant Data Team, Greensboro, NC USA.

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Walter, L. (2005). Climatic constraints drive the evolution of low temperature resistance in woody plants. Journal of Agricultural Meteorology, 61(4), 189–202. https://doi.org/10.2480/agrmet.61.189 

Weakley, A.S., J.C. Ludwig, J.F. Townsend, and G.P. Fleming. (2020). Flora of Virginia. With significant additions and updates. Bland Crowder, ed. Mobile app. Foundation of the Flora of Virginia Project Inc., Richmond, and High Country Apps, Bozeman, Montana.