Red Bay

Sara Meissner

Introduction

This little tree might seem generic, but it hides a powerful smell! Reaching less than 50 feet tall, Red Bays have smooth, lance-shaped leaves arranged alternately on their branches. But a closer look reveals some key distinctions from other woody plants: rusty brown hairs along the twigs, buds, and undersides of leaves. Also, when crushed, the leaves emit a strong and spicy odor. Red Bays are evergreen, blooming with inconspicuous yellowish flowers in early summer and producing round, dark blue fruits in early fall (Virginia Tech Dendrology). These make it an important resource for wildlife and pollinators alike. Read on to learn more about this unique local specimen!

All photos by Sara Meissner

Classification

Scientific Name: Persea borbonia

Common Names: Red Bay, Redbay

Kingdom: Plantae

Phylum: Anthophyta

Class: Dicotyledoneae

Order: Laurales

Family: Lauraceae

Genus: Persea

Specific epithet: borbonia

(explorer.natureserve.org)

Niche and Habitat

Red Bays grow along the coastal plain of the southeast, from warm-temperate to semitropical climate zones (USFS SRS). Generally found near swamps, low woodlands, and in coastal forests, this small tree can grow in moist sandy to mucky soils. It is also tolerant of full sun to partial shade and is hardy against salt (NC State Extension). Red Bays are only moderately fire-resistant and therefore will be damaged by any fire. Any burns above low severity will likely kill young plants (USFS FEIS).

The fruits of this tree are highly beneficial to wildlife. Turkeys (Meleagris gallopavo) and songbirds eat the seeds, and white-tailed deer (Odocoileus virginianus) and black bears (Ursus americanus) will eat the foliage and fruit. They can also provide cover for gray squirrels (Sciurus carolinensis). These animals help disperse the seeds to new areas, if overstory competition allows. Red Bays are the primary host plant of at least two species of swallowtail butterfly and attract many other pollinators (USFS FEIS).

Red Bays have been observed in all light green and yellow counties. State presence is noted with dark green. Yellow counties consider the Red Bay to be "rare".

Map from BONAP (http://bonap.net/MapGallery/County/Persea%20borbonia.png)

Evolutionary History

Red Bay’s tendency towards wet soils and wetland edges has allowed it to focus development away from fire-resistance and towards methods of seed dispersal. Related to the Avocado (Persea americana), the fruits seem to be tasty and are eaten by many animals. The leaves are also very flavorful, emitting a strong and almost spicy aroma when crushed that can be substituted for traditional “bay leaves” in human cooking (USFS FEIS). This latent scent could help attract herbivores to eat the fruits, and pollinators to visit the small flowers. The leaves are also high in calcium, making them nutritionally beneficial.

The Red Bay also has resistance to most insects and diseases (see Conservation below for the exceptions). Insect hosts do not usually do more than superficial damage to the leaves, and antifungal compounds in the roots give further protection from diseases that are dangerous to other Persea species (USFS SRS).

Harmless psyllid galls are common on Red Bay leaves, curling their edges and often appearing yellow, green, or black.

Environmental Impacts

Red Bay is a beneficial member of many plant communities and detrimental to none. These trees do not form dense groves and can be stunted to shrubby in shadier locations (USFS SRS). As mentioned above, they provide a significant source of food to certain species, and the US Forest Service recommends including Red Bays along intermittent streams in southern pine plantations to boost their wildlife habitat value (USFS FEIS). Red Bays can also be used in restoration projects in wetlands and for reclamation at phosphate mines. Their versatility across wet-soiled areas makes them a consistent benefit.

Conservation

Despite a general resistance to insects and disease, Red Bays face a significant threat in both categories. As such, they are classified as Imperiled in North Carolina (explorer.natureserve.org).

Laurel Wilt Disease is a fungal infection spread by the invasive Redbay Ambrosia Beetle (Xyleborus glabratus) as it bores into the trunks and branches of mature trees in the whole laurel family. It was initially discovered in Georgia in 2002 and has now spread along the Atlantic coast to North Carolina and westward into Texas (USDA NISIC). The introduced fungus essentially strangles the tree, depriving the vascular system of water, causing wilt and mortality within a few weeks to months. Infected areas often see mortality rates of over 90 percent of trees above one inch on diameter. The disease also affects two endangered plant species present in North Carolina, Pondspice (Litsea aestivalis) and Pondberry (Lindera melissifolia). There are currently no effective controls or cures besides stopping the transportation of firewood and burning or burying infected trees on site (NC FS).

And secondly, the Black Twig Borer Beetle (Xylosandrus compactus) attacks living twigs and small branches of many tree species, boring into the pith to raise broods. This causes the twig to wilt and die rapidly, often being misdiagnosed as the more serious Laurel Wilt. Infestation by this beetle will generally not be fatal for larger trees but can cause mortality in the small Red Bay shrubs that sprout after Laurel Wilt decimation, hindering recovery (University of Florida).

Leaves change color to a sickly green as they begin to wilt.

Eventually, they will die altogether as vascular flow is cut off.

Bore holes of Xylosandrus compactus. Xyleborus glabratus holes are similar.

Interior view of X. compactus in her brood chamber.

Friends or Foes?

In their moist habitats, Red Bays are usually associated with other common wet trees like loblolly (Pinus taeda) and pond pines (Pinus serotina), bald cypress (Taxodium distichum), red maple (Acer rubrum), oaks (Quercus spp.), and tupelos (Nyssa spp.), and are a major component in Sweetbay-Swamp Tupelo-Redbay forest cover types. Smaller species like yaupon (Ilex vomitoria), inkberry (Ilex glabra), lyonia fetterbush (Lyonia lucida), and wax myrtle (Myrica cerifera) are also close associates (USFS SRS).

Red Bays are not tolerant of persistent shade and so compete against their canopy-creating neighbors. They take advantage of edges and gaps caused by disturbances, often forming downstream “tails” of growth in Florida low hammocks that are visible from the air (USFS FEIS).

Videos

For more information:

The North Carolina Extension website features more identifying characteristics and needs of the Red Bay for gardeners looking to improve the native plant diversity of their yards or care for wild specimens: https://plants.ces.ncsu.edu/plants/persea-borbonia/

Especially important in our Southeastern ecosystems, learn about the relationship between Red Bays and fire from the US Forest Service: https://www.fs.fed.us/database/feis/plants/tree/perbor/all.html

For a more detailed breakdown of Laurel Wilt and how it is affecting North Carolina, check out the Frequently Asked Questions from the NC Forest Service website: https://www.ncforestservice.gov/forest_health/forest_health_laurelwiltfaq.htm

For regional information, articles, and resources relating to Laurel Wilt, have a look at the National Invasive Species Information Center page from the USDA: https://www.invasivespeciesinfo.gov/profile/laurel-wilt

The University of Florida, a hot-spot for Red Bays, has more information on how to identify and disrupt the spread of Black Twig Borers: http://entnemdept.ufl.edu/creatures/trees/black_twig_borer.htm

And if you are feeling adventurous, try cooking with Red Bay leaves instead of the store-bought variety: http://www.eattheweeds.com/persea-borbonia-palustris-humilis-and-americana-too-2/

Resources

Brendemuehl, R. H. (n.d.). Redbay. US Forest Service, Southern Research Station. https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/persea/borbonia.htm

Dixon, W. N., Woodruff, R. E., & Foltz, J. L. (2017, December). Black twig borer. Featured Creatures, University of Florida Entomology & Nematology. http://entnemdept.ufl.edu/creatures/trees/black_twig_borer.htm

Laurel Wilt. (n.d.). USDA National Invasive Species Information Center. https://www.invasivespeciesinfo.gov/profile/laurel-wilt

Laurel Wilt Frequently Asked Questions. (2017, Jan 17). North Carolina Forest Service. https://www.ncforestservice.gov/forest_health/forest_health_laurelwiltfaq.htm

NC State Extension. (n.d.). Persea borbonia. North Carolina Extension Gardener Plant Toolbox. https://plants.ces.ncsu.edu/plants/persea-borbonia/

Persea borbonia Red Bay. (n.d.). NatureServe Explorer. https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.154633/Persea_borbonia

Seiler, J., Jensen, E., Niemiera, A., & Peterson, J. (2019). Redbay. Virginia Tech Dendrology. http://dendro.cnre.vt.edu/dendrology/syllabus/factsheet.cfm?ID=302

Van Deelen, T. R. (1991). Persea borbonia. In: Fire Effects Information System. US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). https://www.fs.fed.us/database/feis/plants/tree/perbor/all.html

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