Peter Zale and Anthony S. Aiello search for azaleas in the deep south.

In September 2021, we embarked on a trip to collect azaleas, particularly Rhododendron austrinum, along the Gulf Coast in deep southern Alabama and Georgia. Interest in native azaleas is widely shared amongst horticulturists, botanists, and pretty much anyone even casually interested in plants, so as the trip planning came into focus, unforeseen opportunities to share field work with colleagues and friends helped transform the trip from a simple seed gathering exercise into a memorable experience steeped in southern hospitality.

The reality of plant exploration is that sometimes it can be rather clinical in planning and practice. This is especially true in the U.S., in-depth publications and plentiful herbaria provide detailed location information for even the rarest of species; while this increases the chances of successful collecting, it also dampens the spirit of true exploration, to the point where seed collecting can feel no more satisfying than checking items off a to-do list. Even so, there remain intangibles of plant exploration that cannot be predicted. The location, people, food, and culture give the trip personality, context to the collections, and define the overall experience. In the post pandemic world, the importance of seeing and interacting with people cannot be understated.

Rhododendron austrinum, (Florida azalea) is a species of restricted distribution and conservation concern (Nature Serve: Globally Vulnerable (G3)) across its range on the Florida panhandle and surrounding adjacent counties in Alabama, Georgia, and Mississippi. It most typically grows in the rich, mixed hardwood forest of shallow ravines, although the Gulf Coast Florida populations in Santa Rosa County occur in “sugar sand” soils along the edges of blackwater rivers which may experience tidal influence and brackish water intrusion. These riverside habitats host a staggering diversity of interesting plants, including multiple species of Sarracenia, and the fabled Lilium iridollae, and an array of choice woody species. Within its limited range, Florida azalea shows variability in phenotype and ploidy, with northern populations generally diploid with yellow-orange flowers, and southern populations usually tetraploid and pink in color. Throughout its range, it occurs sympatrically with a variety of other native azalea species, but most commonly R. alabamense, R. canescens, and R. viscosum (sensu lato). Despite its southern origins, R. austrinum is widely reported as a “good doer” with surprising cold hardiness to USDA hardiness zone 5. This, with consideration of its early flowering, overall ornamental value, and conservation value, makes it an easy target for ex situ collections and display. In the southeastern U.S., this and other native azaleas are often referred to as “honeysuckle,” not to be confused with the genus Lonicera, providing a lesson on the importance, history, and regional nature of plant vernacular names, especially when searching for clues about azalea occurrences in the wild.

The first phase of the trip took place at the Solon-Dixon Forestry Center of Auburn University, where we were invited by colleagues from the Auburn’s Davis Arboretum to join them, colleagues from the Polly Hill Arboretum searching for Stewartia, and local azalea and woody plant experts. Solon-Dixon lies at the juncture of Covington and Escambia Counties in Alabama and is bounded in some areas by large tracts of Conecuh National Forest. While the primary purpose of the forestry center is to provide educational experiences for Auburn’s forestry students, a diversity of natural areas can be found scattered around the property. Here, a rich and changing assortment of floristic curiosities and target species could be found, with 1015 species found in its 5300 acres, accounting for 25% of all known vascular plant species in Alabama. The floristic diversity itself is a reflection of the complicated geology in the region, resulting in a variety of habitat types, including mesic limestone ravines, sand hills, rocky outcrops of ironized sandstone with a xeric flora, and sandy wetland savannahs.

The floristic diversity itself is a reflection of the complicated geology in the region, resulting in a variety of habitat types.

As the group of eight of us started searching, it became immediately evident that Rhododendron canescens was the most abundant azalea in the region, found throughout mesic flatwoods, especially adjacent to small stream courses. Not surprisingly, R. austrinum was more exacting in its habitat preference. We found it growing in a unique habitats: a shallow ravine created by a meandering stream that resulted in a comparatively high degree of topographic relief compared to nearby areas. The small bluffs of the stream created unique habitat for a variety of rare species including Stewartia malacodendron, Rhapidophyllum hystrix, Trillium underwoodii, and R. austrinum. Here we found it growing in shrubby thickets near the tops of the bluffs in close association with R. canenscens under a canopy of Pinus glabra, Magnolia grandiflora, and myriad other hardwoods. Despite the shaded conditions at the site, flowering and seed set for the population was good enough that we could make modest collections of seeds. After an evening of dinner, seed cleaning, and conversation, we set sights for our next collecting location in Southwestern Georgia.

Trip planning was aided in large part by a fortuitous article published in the Spring, 2021 issue of The Azalean (Journal of the American Azalea Society) that detailed the discovery and documentation of a fascinating occurrence of azalea species near Leesburg, Georgia named “Monica’s Swamp.” This private 44-acre azalea preserve lies at the northeastern limit of distribution of R. austrinum along tributaries of the Flint River, growing near or sympatrically with R. alabamense, R. canescens, R. viscosum, and putative hybrid swarms with R. canescens. What started as an initial curiosity to know which kinds of “honeysuckle” grew on a neighboring property, exuberant preserve-owner Monica Wiliams ended up purchasing the property and has since developed a strong interest in stewarding, documenting, and preserving this unique concentration of azaleas and associated sand hills flora. Like the Solon-Dixon property, Monica’s Swamp is a lesson in geology and hydrology, where subtle changes in elevation and soil types provide a mosaic of different habitats and ecotones that make for interesting breeding grounds for azaleas. Despite growing in close proximity, the four azalea species are separated by changes of just a few feet of elevation and the resulting habitat differences. Rhododendron austrinum and R. canescens shared similar habitats along small seepage streams. Rhodoendron viscosum is a species of peaty, inundated soils often found near open water of shallow ponds. Rhododendron alabamense is an upland species, growing on deep sandy soils at “high elevations” in sand hills throughout the swamp. Wherever they occur on her property, Monica has documented the plants, making notes and taking photographs on their phenology and floral phenotypes, resulting in an all-encompassing understand of the plants throughout her property. Her keen observations allowed us to make highly specific seed collections based on her observations.

Seed collecting started quickly after we arrived in the morning and lasted until mid-afternoon; we made the first collections of R. austrinum, literally in the front yard of Monica’s neighbor, while R. canescens and R. viscosum collections were made a short distance away between Monica’s and her neighbor’s house. We were not prepared for how easily accessible the plants would be, nor the extent of work Monica had put into clearing miles of golf cart paths to access the rare plants throughout her preserve. A good portion of the day was spent winding our way through the preserve while Monica discussed her extensive efforts in clearing paths and freeing the azaleas from the fire-suppressed scrub— giving them a chance for more sunlight and the opportunity to luxuriate. The culmination of the tour was the presentation of the “The Queen”—a remarkably large and vigorous specimen of R. alabamense judged by several experts as perhaps the most exceptional specimen of R. alabamense known anywhere. Its beautiful and fragrant creamy-white flowers, near-perfectly uniform habit, and large size (12 feet tall by 15 feet wide) made it clear why it was given its moniker. It’s hard to imagine a more fitting end to the day than to collect a few treasured capsules from this revered specimen— unique not only for its dimensions, but also a likely source of good genetics for cultivation in northern regions. Satisfied with our seed collections and reeling from the deluge of plants, information, landscapes, and hospitality we encountered through our visit to the south, we retreated to Albany, GA for the evening, and a couple of days later, back to Longwood Gardens.

Peter Zale and Anthony S. Aiello are the associate directors for conservation, plant breeding, and collections at Longwood Gardens in Chester County, Pennsylvania.

From “free” to “friend”…

Established in 1911 as the Bulletin of Popular Information, Arnoldia has long been a definitive forum for conversations about temperate woody plants and their landscapes. In 2022, we rolled out a new vision for the magazine as a vigorous forum for tales of plant exploration, behind-the-scenes glimpses of botanical research, and deep dives into the history of gardens, landscapes, and science. The new Arnoldia includes poetry, visual art, and literary essays, following the human imagination wherever it entangles with trees.

It takes resources to gather and nurture these new voices, and we depend on the support of our member-subscribers to make it possible. But membership means more: by becoming a member of the Arnold Arboretum, you help to keep our collection vibrant and our research and educational mission active. Through the pages of Arnoldia, you can take part in the life of this free-to-all landscape whether you live next door or an ocean away.

For more tree-entangled art, science, and writing, subscribe to Arnoldia by becoming a member of the Arnold Arboretum.