storms After the
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Hurricane delivers a blow to efforts to preserve rare and endangered Torreya By LILA UZZELL As Hurricane Michael bore down on the Southeast in October 2018, the entire range for the critically endangered Florida Torreya – North America’s rarest conifer – lay within the storm’s path. The Category 5 hurricane devastated the Florida Panhandle and southwest Georgia, where an estimated 80 to 90 percent of the forest canopy was lost across the three-county range of this native evergreen tree. Downed trees were tossed throughout the steep ravines where the conifer grows, burying Torreya (Torreya taxifolia) in the debris or completely crushing the plant, which for years the Garden has worked hard to preserve. Today, overstory trees 100 years old or more remain piled on top of one another like a game of pick-up sticks. Commonly known as Florida nutmeg, Torreya populations once boasted 650,000 plants – a number that crashed in the 1950s because of overharvesting, along with a fungal pathogen that restricts reproduction of the species. Climate change and habitat loss have reduced the species’ already restricted range – wild populations occur only in steep ravines along the eastern edge of the Apalachicola River watershed. Torreya taxifolia
Team members remove debris from atop Torreya.
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WHY IT MATTERS
Collaboration through volunteer and governmental partnerships can yield success in preserving endangered plant species. The devastation caused by Hurricane Michael only exacerbated an already unfortunate set of circumstances for this imperiled species, making collaborative conservation efforts all the more significant. Since 1990, the Garden has become a leader in the conservation of Torreya, surveying and monitoring both wild and seed-orchard populations in collaboration with volunteer, local, state and federal partners, including the Torreya Keepers, the U.S. Fish & Wildlife Service, the Nature Conservancy and Florida’s Torreya State Park. After the hurricane, a long-term strategy has become essential to capture Torreya’s response to the dramatic habitat changes resulting from the storm. Losing up to 90 percent of the mature overstory canopy has altered the physical environment of the ravines, and the conifers are now faced with increased sun exposure, affecting transpiration rates, soil moisture and competition with other species. This landscape alteration is unprecedented for Torreya, so it is vital to monitor individual trees over time. Additionally, navigating the steep ravines now tangled with tree branches, trunks and other debris will be increasingly treacherous in coming years. For researchers’ safety and practical purposes, a subset of Torreya has been chosen to represent the remaining wild population, including 40 trees around which long-term monitoring plots have been established. Staff and volunteers returned last December to assess the condition of those trees and the surrounding forest. Changes in relative humidity and air temperature are logged and stored as field crews document the quantity and size of downed trees and successional changes in ground cover vegetation within about an 11-yard radius of each Torreya. Drones 4 PlantIntel
CLOCKWISE, FROM LEFT: Conservationists monitor the status of seedlings protected by wire cages, while staff survey the storm damage.
also are used to record aerial imagery of each plot and will be monitored yearly to look at shifts in seasonal vegetation response. Hurricane Michael provided both disastrous change in the Torreya’s environment as well as the opportunity to use scientific methods to objectively track the tree’s recovery or decline. The Garden plans to monitor these 40 trees bi-annually over the next five years to assess how Torreyas respond to these environmental changes.
LILA UZZELL is the Garden’s Conservation Assistant and a Field Biologist. Conservation and Research Manager Laurie Blackmore contributed to this article.
Plant. Eat. Repeat. Workshops connect residents with healthy food, sustainable communities By MOE HEMMINGS Many home gardeners seek the know-how for growing the type of food they desire. At the same time, local community gardens suffer from a lack of participation. “Plant. Eat. Repeat.” is there to connect the two. The new program provides hands-on garden instruction and demonstrations during workshops at community gardens. Offered in partnership with the Food Well Alliance, a network of local leaders working to build thriving farms and gardens, and AgLanta, the City of Atlanta’s urban agriculture program, the Garden series aims to build a strong connection among residents to their food and where it comes from. Programs like “Plant. Eat. Repeat.” provide practical ways participants can grow healthy food while cultivating sustainable growing spaces and enriching communities. Plant. Eat. Repeat., launched last year as a pilot program, includes free workshops, open to anyone, in neighborhoods around Atlanta. Classes cover seasonally-appropriate topics from seed starting to harvest and everything in between. The project provides an opportunity to bring knowledge and skill building to those who
desire it while also exposing budding gardeners to existing community growing spaces and the wealth of knowledge found there.
Some host garden sites are also participants in AgLanta Grows-A-Lot, a program that invites entrepreneurs, non-profits and residents to apply for a five-year renewable license After presenting 15 workshops in six to adopt a vacant, city-owned property to communities over three seasons, the program start a new urban garden or farm. Hosting has yielded a lot of produce, and gardeners are workshops at these sites has helped expand helping residents build a stronger connection the knowledge of AgLanta growers, who are with their food. Through often new to growing food networking with neighbors in an urban environment. WHY IT MATTERS and other gardeners, “Each class was engaging participants seem to relish the and informative. Growers Growing fresh opportunity to ask questions learned important skills, ingredients about their own growing ranging from starting encourages spaces and enjoy swapping seeds to the importance plants, knowledge and of regenerating Atlanta’s consumers to resources. neglected urban soil (while eat healthy food having FUN!),” said In 2020, the Garden and its Elizabeth Beak, the City while cultivating partners hope to incorporate of Atlanta’s Sustainability more ways for participants to sustainable gardens + Food Systems Planner. engage in hands-on learning “Growers can’t wait for the and productive experience, such as a work ‘Plant. Eat. Repeat.’ 2020 communities. day for gaining volunteer sessions to begin.” experience for helping those who tend to plots in a host garden. They are also afforded a chance to put the knowledge they have gained about planting, grooming MOE HEMMINGS is the Garden’s and harvesting to practical use as well give Community Outreach Manager garden plot-holders an opportunity to showcase their spaces and share knowledge. atlantabg.org 5
Hidden gem An often-overlooked indoor garden, Desert House gets a colorful refresh By TREY FLETCHER The Garden’s Desert House may be a little off the beaten path inside the Fuqua Conservatory, but it provides a fascinating counterpoint to the rainforest environment found in the building’s Tropical Rotunda next door. Rainforests are well known for extremely high levels of biodiversity among their plants and animals, but in the desert there are ecosystems with biodiversity that rival and sometimes exceed those found in much more humid tropical forests. The Desert House focuses on two such arid regions – the desert portions of southern Africa and Madagascar. Both places are home to some of the most diverse and unusual groups of plants found anywhere in the world. Many of the wild populations of the plants on display are threatened because of habitat loss and overcollection, so a stroll through the Desert House is a great way to become better informed about this fascinating group of plants and the ecosystems where they thrive. Some types of succulents found in the Desert House include Euphorbias, many of which resemble cacti but aren’t closely related genetically; Cycads, which superficially resemble palms but are an ancient group of plants dating to the time of dinosaurs; and the highly unusual and rare plants within the family Didiereaceae, restricted to the spiny forests in a small part of southwestern Madagascar. 6 PlantIntel
WHY IT MATTERS Displaying plant collections for education and enjoyment plays a major role in the Garden’s mission.
The form and texture of these plants come together to provide a look and feel to Desert House that is strikingly unique. Others, such as the beautiful desert rose (Adenium sp.), rosy periwinkle (Catharanthus roseus) and an array of succulent asters (Senecio sp.) provide accents of color in the displays. To further enhance the Desert House’s varying textures and brilliant colors, the Garden is acquiring many additions to its succulent plant collection. A selection of rare southern African desert bulbs that bloom in an amazing array of colors at various times throughout the year is being installed this spring. Another upcoming addition is a new collection of Lithops, also known as “living stones”. These tiny succulent plants are native to South Africa, Namibia, parts of Botswana and Angola. Lithops are often nearly indistinguishable from the rocks that litter the surface in the extremely dry and harsh ecosystems in which they are found. Despite their inconspicuous appearance, they produce beautiful flowers in a variety of colors. The Desert House has always been a hidden gem inside the Conservatory, and with the new additions, it will be an even more appealing part of the gardens-under-glass experience the next time guests visit.
TREY FLETCHER is Curator of the Garden’s Desert House.
LEFT: The spiny plants of the Desert House are often confused with cacti but are actually Cycads. ABOVE: Adenium obesum
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By EMILY COFFEY Tolumnia bahamensis
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Neither treacherous terrain, poisonous plants nor devastating hurricanes can stop the Garden’s intrepid conservationists when it comes to hunting an elusive, critically endangered orchid. Last spring, two members of the Conservation & Research team embarked on a plant hunt to find the Dancing Lady Orchid. Tolumnia bahamensis is a beautiful, critically endangered plant found among the rare coastal rosemary scrub habitat along south Florida’s Atlantic coast and was historically documented on three of the Bahamian islands. For the last nine years the Garden has been actively working to protect the Florida plants by increasing pollination rates, augmenting the populations and tracking survivorship. When the team started working with the orchids at Florida’s Jonathan Dickinson State Park, only 40 individual plants remained in the wild. With consecutive recovery work, more than 2,000 plants have been used to
augment the park’s wild populations. This population is still at great risk given the pressures of habitat loss and fire; however, with careful habitat management, continued propagation and augmentation the scarce populations stand a chance of surviving. With the success of the Florida work, the staff wanted to determine if the previously documented populations in the Bahamas were still alive. The last documented there were from a botanist taking herbarium samples more than 40 years ago. With a small grant from the World Orchid Congress, the team hopped on a plane and launched a plant-hunting expedition to search for the orchids on Andros and Abaco islands where they were documented in the past.
After a long day-and-a-half on Andros spent hiking across mangrove flats and through dense Poisonwood stands, they found Dancing Lady flowers gently swaying in the breeze. Much to their excitement and joy the population was in full flower and looked very healthy. The team worked to document the population and collect the needed data to enable them to return during the fall when the plants were in fruit. Following the first island’s success, they were eager and hopeful to find the next population on Great Abaco Island. Again, the search was extremely long and difficult – including crawling on hands and knees through dense Poisonwood stands – but at the end of the second day the largest population of the species to date was discovered. Words could not express how happy the team was to find this intact population on the eastern Atlantic side of Abaco. The next steps for this project had involved returning to search for the last population on Grand Bahama, conducting a full population assessment for each island and collecting seed
Michael Wenzel, the Garden’s Manager of Plant Documentation, examines a flower.
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ABOVE: Storm damage extends across a mangrove flat on Great Abaco Island. BELOW: The Dancing Lady Orchid is a critically endangered plant.
to safeguard the population long-term given the instability from the proximity to sea levels. It also involved conducting genetic analysis to determine the diversity of the Florida and Bahamian populations. In early September, however, when the team had hoped to be collecting seed, Hurricane Dorian, the most intense storm on record to hit the Bahamas, struck Abaco. Dorian reached its peak intensity during landfall on Great Abaco Island with sustained winds of 185 miles per hour and gusts of up to 220 miles per hour, moving at the brutally slow pace of 5 miles per hour. The storm then moved to Grand Bahama, where one of the three historic populations of Dancing Lady Orchids was documented. There, the storm further slowed to 1.2 miles per hour. The devastation left was unimaginable with towns turned to fields of rubble and homes and concrete buildings flattened. Nearly every building in Marsh Harbour on Great Abaco, where the staff had stayed just months before, was damaged, destroyed or entirely lost. As rebuilding of the communities and islands begins, the team is preparing to assist when the time comes again to search for these dancing jewels and continue this critical conservation work. In the meantime, the search is on back home for grants and donations to continue the safeguarding work for protecting this beautifully unique species.
EMILY COFFEY, PhD., is the Garden’s Vice President, Conservation & Research.
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WHY IT MATTERS
Restoring and managing habitats is critical to preserving populations of endangered plants through conservation and research.
Field test Nursery evaluates plant collections under Georgia conditions By SCOTT McMAHAN Tucked away on the back side of the Atlanta Botanical Garden, Gainesville, is an outdoor science lab that’s all about trial-and-error.
WHY IT MATTERS Evaluating plants grown from seed from other parts of the world is key to the conservation of plants everywhere.
The evaluation nursery, not open to the public, is designed to allow staff to test plants in the ground given a variety of exposures ranging from full sun all day to filtered light in a woodland setting. The nursery represents a third critical component in the Garden’s International Plant Exploration Program; the other two are field exploration for seed collection trips throughout Southeast Asia and hosting visiting scholars from other institutions. In the evaluation nursery, plants are monitored regularly for their potential to become invasive, their susceptibility to insects and disease, their hardiness in extremes of cold, hot, dry and wet conditions, and their ornamental appeal. Most plants are monitored for up to three to five years in order to continue to make room for new evaluations. The field nursery is not meant to
be designed, planted or maintained as a garden; instead, it is a place to trial new collections of plants fully exposed to north Georgia weather conditions. Work on the project began in earnest last summer. Horticulturists began planting the first plants in July – only after water was made available on site. By the time an 8-foot deer fence was built around the nursery and nearly three-quarters of a mile of PVC pipe installed and connected to a well, the heat of the summer had set in. Yet, with the help of a large auger bit and machinery, more than 300 plants were installed by the end of the year, representing nearly 200 taxa, or plant groups. Virtually all of the plants being grown in the field are of wild provenance which makes the collection even more important when added to the diversity of plant material within the nursery. So much so that the U.S. Department of Agriculture has asked the National Arboretum to collect pressed-plant vouchers of all of the nursery plants for housing in its Herbarium in perpetuity.
SCOTT McMAHAN is the Garden’s Manager of International Plant Exploration.
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By BECKY BRINKMAN
Coryanthes mastersiana
Coryanthes speciosa
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Bucket Orchids (Coryanthes species) produce some of the most fascinating flowers in all of nature. The flower’s intense fragrance and extraordinary bucket facilitate pollination – the product of the close coevolution of the orchid and its pollinator.
WHY IT MATTERS Displaying plant collections for education and enjoyment plays a major role in the Garden’s mission.
Coryanthes belong to a large group of neotropical orchids pollinated by euglossine bees – large iridescent bumblebee relatives that collect floral fragrances. Coryanthes flowers emit intense fragrances that attract the bees. The flower’s lip forms a bucket into which the bees secrete drops of watery liquid containing pollen. Male bees of the genus Eulaema visit the flowers and scratch at the base of the lip to obtain the fragrance strength. In doing so, they often slip and fall into the bucket. With their wings wet, the only escape is through the narrow opening at the rear of the bucket, close to the tip of the column. In squeezing through, the bee has the pollen mass attached to his abdomen. The process is repeated at another flower where the pollen is deposited on the flower’s stigmatic surface, affecting pollination. Little wonder that these Euglossine beepollinated orchids are one the Garden’s most fascinating flagship collections.
BECKY BRINKMAN is the Garden’s Fuqua Orchid Center Manager
Coryanthes macrantha
Coryanthes alborosea
Coryanthes bruchmuelleri
Coryanthes macrocorys
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DEEP ROOTS
Cacti and succulents collection extends to Garden’s early days 14 PlantIntel
Echinocereus triglochidiatus
Long before they became trendy, many cacti and succulents called the Garden home, some dating back to the 1980s. By AMANDA BENNETT The recent surge in the popularity of succulents is no wonder. Their ease of care, widespread availability and clean structural look appeal to busy plant lovers. Most recently, the succulents trend has emphasized indoor plants, but many are unaware how well they grow outdoors in the Southeast – the reason the Garden has long been a fan. In 1988, as the Dorothy Chapman Fuqua Conservatory was nearing completion, part of the overall garden design was that plant collections planned for inside the building would be mirrored with their hardy, sometimes New World counterparts just on the other side of the glass. Palms, conifers, cacti and succulents bordered three sides of the building for visual extension. With that in mind, the first hardy cacti and succulent outdoor garden was planted. Palms and conifers already enjoyed mass appeal -- but in Atlanta cacti and succulents were nearly unheard of as a landscape option. Most don’t realize that Georgia has native yucca and cacti: Yucca gloriosa, Y. filamentosa, Opuntia humifus, and O. compressa. The Garden’s overall plant pallet was not typical of the Southeast but proved highly successful with modified soil and the warm climate extending the length of the Conservatory’s southeastern side. Showcasing other opuntias and yuccas as well as Agave, Cylindropuntia, Echinocactus and Echinocereus, the forms, textures and stunning flowers spoke for themselves. Many of these plants were mail ordered, and a significant gift of cacti was made in the mid90s by Dr. J. Gordon Barrow – all of which he had grown from seed. Six years ago, when the Garden began redesigning its “eastern edge” as a new Skyline Garden, plans included terraces for hardy cacti and succulents based on the success of the original collection. For more than three years, staff traveled to Mexico’s Ethnobotanical Garden of Oaxaca to gain specific design insight for cacti and succulents, and to Tucson, Arizona, to hand select 8-foot Yucca faxoniana, 6-foot Nolina nelsonii and 4-foot Yucca rostrata. Though cacti and succulents are more readily available around Atlanta, retailers focus mostly on indoor plants, so most of the new 11,000-square-foot garden’s plants had to be sourced primarily in Texas, Arizona, Utah, Colorado and Florida. More than 147 taxa, or plant groups, were planted before the May 2017 grand opening. Forming the garden’s structure are modern raised planters made of corten steel with an elaborate drainage system beneath their custom-blended soil. The starting point for the plant pallet were plants that performed best in the old garden. Some of the original plants, dug and saved, were transplanted to their new homes 29 years later. More than 16 species of Agave, 60 different Opuntia and nine species of Yucca form the foundation of the collection. A remarkable Beschorneria sp., fastgrowing Agave ‘Jon Jon’ from Peckerwood Garden, and Mammillaria and Echinocereus from the Lady Bird Johnson Wildflower Center are among the prized gifts from colleagues. The Garden also acquired a
TOP: The Skyline Garden features a series of terraces. ABOVE LEFT: Mammilaria prolifera; RIGHT: Opuntia ovata
species Opuntia collection of more than 60 plants from Hayes Jackson at the Anniston History Museum. Since the garden’s completion, several winter storms and wet springs have had some impact. Some Agave americana and Nerium oleander ‘Mathilde Ferrier’ couldn’t withstand several snow and ice days in the first year. Similarly, Mammillaria ‘Copper King’ that had defied the odds in the old garden as well as some of the pickier and more obscure Agave called it quits. But the losses have provided opportunities for more planting, currently at 216 taxa and counting.
WHY IT MATTERS Displaying outstanding plant collections demonstrates a public garden’s commitment to educating guests of the critical need to preserve them for generations to enjoy. AMANDA BENNETT is the Garden’s Vice President, Horticulture & Collections.
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Taking it
to the bank Garden selected for collecting, safeguarding seed of endangered plants By JASON LIGON The safest place to store the seeds of the most endangered plant species may be tucked away in a chilly freezer. The Garden is home to such a seed bank, a concentrated cache of genetic diversity. This frozen world lends a sharp contrast to the dynamic environment facing botanical species in their natural habitat. Last year’s opening of the Garden’s Southeastern Center for Conservation amplified attention on its developing seed bank, among the most important of conservation tools.
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CLOCKWISE, FROM LEFT: An empty umbel of Coastal Mock Bishopweed drifts downstream; umbels hold on to their last remaining seeds of the season; 10 percent of a plant’s seed is collected for banking. (Photos by TJ Snider)
The conservation seed bank and the protocols guiding the movement of seed from the wild to the bank are being developed in accordance with best practices set forth by the Center for Plant Conservation. The network of more than 50 institutions that aim to conserve and restore North America’s rare native plants selected the Garden to scour the coasts of Georgia and South Carolina in search of seed from two globally-endangered species for safeguarding in seed banks: Coastal Mock Bishopweed (Ptilimnium ahlesii) and Radford’s mint (Dicerandra radfordiana).
“Too early, and you’ll bring back immature seed. Too late and conservationists show up to an empty plant umbel with its seed already whisked away with the tide,” Field Biologist Lila Uzzell said. “You can’t catch ‘em all, but at what point do you make the call to turn back in your kayak?”
Last year, the perfect place and time for collecting seed from Coastal Mock Bishopweed turned out to be at the water’s edge or on floating mats of vegetation on twisting coastal waterways under Georgia’s punishing mid-July sun. Timing was essential.
Capturing enough genetic diversity is always a concern with seed banking, in which harvesting only 10 percent of the available seed is the goal. While it’s simple to select seed easily accessible at the road’s edge, sometimes collectors have to watch their step and carefully pick
WHY IT MATTERS WHY IT MATTERS
Seed storage Seed storage is critical for is critical for conserving the conserving the genetic diversity genetic diversity of the most of the most endangered plants. endangered plants. atlantabg.org 17
Two Garden conservation team members look for Coastal Mock Bishopweed seeds alongside coastal waterways.
their way into the middle of a densely populated site or kayak another half-mile against the tide to capture a more representative sample from across the species’ entire range. In the case of Radford’s mint, staff found plants where pavement gave way to sandy corridors beyond a long-forgotten cemetery. With their bright fuchsia flowers, the plants were either so dense that a dozen seedlings would be crushed beneath a single footprint or others so sparse that a bluff separated them. Seed collected from the wild is at risk until dried and safely stored at -20° C. Not all seeds respond well to drying, but those that remain viable after drying are classified as “orthodox”. When orthodox seed is collected from the wild, a dedicated team of conservation interns and volunteers works quickly and meticulously to prepare seed to be dried and frozen, minimizing the time the seed spends under ambient conditions. All seed from last year’s collection trips for the two plants are now protected from the changing climate at seed banks at the Garden and at the National Laboratory for Genetic Resource Preservation in Fort Collins, CO. The number of hours that go into the harvesting, cleaning and record keeping for a conservation seedbank is staggering – more than 50 were needed to process the seed and data of the 1,800 Radford’s mint seeds alone. But, developed over time, the seed bank program is critical for conserving the genetic diversity of the world’s most endangered plant populations and central to the Garden’s conservation work. 18 PlantIntel
Garden conservation staff found Radford’s mint where pavement gave way to sandy corridors on the edge of a cemetery.
JASON LIGON is the Garden’s Micropropagation & Seed Bank Laboratory Coordinator
Forging friendships Through food, partnership forms bonds with refugees By ABBY GALE Gardening and cooking are proving to be the perfect ingredients in a recipe for forging the bond of friendship among Garden visitors and area refugees. For the fourth year, the Garden and an organization called Friends of Refugees have partnered to host a summer weekend event, Refugee Recipe Celebration, during which refugee cooks share unique flavors and traditional cooking methods from their homelands. The relationship began when longtime Garden supporter Susan Spratt invited staff to visit Friends of Refugees’ Jolly Avenue Garden in Clarkston, GA, considered one of the most diverse areas in America. The community garden offers refugees a place that fosters a collective experience of beauty, belonging and friendship. “It seems to me that Jolly Avenue Garden can be an important place for healing,” said Spratt,
WHY IT MATTERS
Community engagement is a critical part of the Garden’s mission in using plants to provide education and enjoyment.
The Garden and Friends of Refugees first decided to work together during summer Garden Chef demonstrations in the Outdoor Kitchen. Those have since become a true culinary adventure as visitors sample tastings from Syria, Nepal, Bhutan, Burma, Sudan, Eritrea, Congo and Ethiopia. In addition, horticulture staff have planted crops such as summer squash, peanuts and okra as display ingredients in the Edible Garden for Refugee Recipe Celebration, and last year, several rows of fruitful roselle, one of the major food plants used in Burmese soups and stews, were added.
who enjoys volunteering there and helping people grow plants they’re familiar with.
Visitors also enjoyed tasty samples of roselle soup, prepared by Growing Leaders, a high school student group that works part-time at Jolly Avenue Garden. “The students truly loved their experience at the Garden,” Davenport said. “To share recipes and stories about their home country and culture to a warm and welcoming audience was very special to them.”
Erin Davenport, Director of Agriculture & Nutrition at Jolly Avenue Garden, said many refugee gardeners were once part of an agrarian community before they were forced from their homelands. Each garden plot at the site provides a safe place for them to nurture plants and develop a sense of community.
The partnership has since grown to include high school student field trip swaps and neighborhood workshops. In Clarkston, sessions have focused on topics such as container gardening with healthy edibles, seed preservation and choosing winter vegetables and herbs.
ABBY GALE is the Garden’s Public Programs Manager.
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MAKING
babies How the Garden propagates its orchids By BECKY BRINKMAN Fuqua Orchid Center Manager
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POLLINATION
The Garden requires a continuous supply of young orchids to replace older plants, keep the Orchid Center full and lush, and to trade with other gardens. But making more orchids from scratch isn’t nearly as easy as producing other plants. For orchids, the simplest methods of propagation don’t apply. Cuttings are out of the question because orchids are monocots (plants whose seed contain only one embryonic leaf), and plant division imposes limitations in quantity and quality of the offspring. Seed propagation is thus the method of choice for orchids, but here, too, are complications that arise from the unique characteristics of orchid seed. Orchid seeds contain no endosperm, or stored food, to nourish the germinating seedling. In nature, orchid seeds derive their food from a fungal organism that serves up the necessary micronutrients. In its absence in cultivation, those micronutrients are supplied through a rich medium in a laboratory. Fortunately, the Garden’s new micropropagation lab provides the perfect setting for germinating orchid seed rather than sending it to a commercial lab. This means that every step in the production of young orchids, from flowering to greenhouse, can be accomplished on site. Here is a step-by-step
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Orchid flowers are pollinated by placing one or more of the pollen masses (pollinia) on the surface of the same flower (a selfing) or the flower of a genetically different plant of the same species (an outcrossing). The ovary with its unfertilized ovules is located behind the flower’s sepals. Pollen cells germinate on the stigmatic surface, releasing sperm cells that follow an elongating pollen tube to the ovules in the ovary. As with other flowering plants, the embryos develop inside the seed when the sperm cells from the pollen fertilize the ovules.
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POST-FERTILIZATION The ovary swells with ripening seeds. Seed maturation inside the ovary takes one to 24 months depending on the species. Notice that the faded flower is still visible at the distal end of the developing capsule.
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THE CAPSULE The ripened ovary of a flowering plant is known as the fruit, and for orchids it’s known as a capsule. Capsules come in a fascinating variety of sizes and shapes. When the capsule is mature, it starts to split longitudinally. This is when the capsule is removed from the plant and the seeds are harvested.
4 HARVESTING THE SEED An orchid capsule can contain a million dust-like seeds. All the seed from one capsule is given a unique lab number, and the information about its parentage, source and maturation length is entered into a database. The seed is divided into two glass vials that are labeled with the lab number: one for sowing and one for storage.
5 SOWING THE SEED
WHY IT MATTERS
The vial of seed is moved to a laminar flow hood for sowing, placed in a tiny envelope of paper and sterilized in a diluted bleach solution to prevent contamination. It is then rinsed and spread on the surface of a gel-like medium containing micronutrients inside a sterile jar bearing their lab number, date and media batch number. The jar is sealed to prevent contamination and placed on light racks in the lab’s culture room.
Propagating orchids from seed ensures lasting collections at the Garden and can help restore threatened populations of rare species in the wild. atlantabg.org 21
6 SEEDLINGS IN FLASKS It takes weeks to months before the seed germinates and seedlings are visible. As the seedlings grow and photosynthesize, they consume nutrients and often need to be transferred to fresh medium in a larger flask. Seedlings can take a year or more before they are mature enough to plant out.
7 DEFLASKING
8 GREENHOUSE SEEDLINGS Trays of young seedlings are moved to a shady humid greenhouse, where they are checked daily for moisture and fertilized every two weeks with diluted liquid fertilizer. After a couple months, trays of seedlings that require brighter light are moved to a brighter greenhouse for hardening off. After a few more months the seedlings are removed from cell trays and potted in individual pots.
Seedlings are removed from the flask as a group with their roots entangled and embedded in agar, which is then gently washed away. Seedlings can then be separated from one another, taking care not to damage the roots. Each seedling is then wrapped in sphagnum moss and planted in an individual cell of a seedling tray.
Orchid technology Staff join global DNA barcoding efforts
used to assist in identification of a species, critical in field identification when the plant is not in bloom.
The Garden is using its vast orchid collection to help in identifying orchids globally by using a method that has shown promise in cases of suspected plant poaching or illegal trade: DNA barcoding.
The research involves collecting a small leaf sample from nearly all orchid species in the Garden’s collection and sending them to the Biodiversity Institute of Ontario for DNA barcode sequencing, in which two genes are identified. Sequences from 763 individual plants in the collection are now being made publicly available through the Barcode of Life Data System.
Thanks to a 2016 grant from the Institute of Museum and Library Services, research scientists are performing DNA barcoding on the Garden’s world-renowned orchid collection. A DNA barcode is a short sequence of DNA that is
DNA barcoding has limitations. It assumes that DNA differences within two genes will suffice to allow for identification. This is not always the case. Sometimes two different species can have the exact same DNA sequence as the genes used for DNA bar-
By LAUREN ESERMAN
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coding, making identification challenging. Last year, the staff led a new project in collaboration with Arbor Biosciences; Dr. Jim Leebens-Mack, Professor of Plant Biology at the University of Georgia; and Shawn Thomas, a graduate student at the University of Missouri, to fill in gaps from DNA barcoding. Together, a system was developed that allows the sequencing of 963 genes from a single plant sample. This “target sequence capture” has the potential to revolutionize genetic analyses of orchids. DNA barcoding examines only two genes, while target sequence capture examines hundreds of genes, greatly increasing the likelihood of finding differences between orchid species.
LAUREN ESERMAN, PhD., is the Garden’s Research Coordinator and a Research Scientist.
PLANT CLOSEUP B l u e b e r r i e s
CLASSIFICATION: The blueberries you eat in a fruit salad or jam are from three different species of Vaccinium. Native to the southern United States, Rabbiteye blueberries (Vaccinium virgatum) get their moniker from the pink color when the fruit is still not ripe. In the Northeast, Highbush blueberries (V. corymbosum) grow wild and are a taller shrub than the diminutive lowbush blueberry (usually V. angustifolium or V. myrtilloides). NOTEWORTHY: There are also blueberries found in the tropics of New World lowland tropical and cloud forests called “Neotropical blueberries�. These interesting plants native to South America, Central America, the Caribbean and southern North America wow Garden visitors with interesting flowers. Look for Vaccinium shrubs in the Edible Garden and a healthy representation of the more than 4,000 species of neotropical blueberries in the Fuqua Conservatory and Orchid Center. HEIGHT & WIDTH: Dependent on type, but allow 4 to 5 feet between blueberry plants. Cross pollination between varieties results in heavier fruit production. USES: Edible fruit, fantastic red for fall color CARE: Plant in loamy, well-drained soil that is acidic, with a pH range of 4.5 to 5.2. Water regularly and keep shrubs mulched to retain water and minimize weeds. To guide the shrub to work on healthy roots and branches, remove any flower buds that appear for the first two years after planting. Prune canes that are diseased or damaged, or very old and no longer productive. PROPAGATION: Mostly by softwood cuttings PROBLEMS: Birds, fungal and bacterial diseases
RALEIGH WASSER is a Horticulture Manager at the Garden.
Vaccinium virgatum atlantabg.org 23
FAMILY: Ericaceae | ZONE: 3 - 9 depending on type | BLOOM TIME: Late spring| LIGHT: Full sun to part shade | NATIVE: North America
The mission of the Atlanta Botanical Garden is to develop and maintain plant collections for display, education, research, conservation and enjoyment.
24 PlantIntel
PlantIntel
| Vol. 2, Issue 1, 2020-21 | The Anna and Hays Mershon President & CEO: Mary Pat Matheson Vice President, Marketing: Jessica Boatright | Editor: Danny Flanders | Designer: Bo Shell