Our Leadership
AmericanHort is governed by experienced senior business leaders who represent diverse industry segments and share a desire to help our industry flourish.
Executive Committee
Kent Fullmer
Chairman
Fullmer’s Landscaping, Inc
Derek Clark
Vice Chairman
Metrolina Greenhouses
J. Harvey Cotten Jr
Treasurer
Horticultural Consultant, Author
Edward Overdevest
Immediate Past Chairman
Overdevest Nurseries LP
Lionel van der Walt
President & Chief Executive Officer
AmericanHort
Directors
Joe Allio
Petitti Family Farms
Ken Altman
Altman Specialty Plants
Patricia Dean
Wadsworth Control Systems
Tom Fessler
Woodburn Nursery & Azaleas, Inc
Christine Fortman
Berridge Nurseries, Inc
Brian Lloyd
Olson’s Greenhouse
Emily Showalter
Willoway Nurseries
Scott Valentine
Express Seed Company
Bradd Yoder
Star Roses and Plants
Bradd Yoder
Star Roses and Plants
Bradd Yoder has worked 31 years for Star Roses and Plants (The Conard Pyle company) including the last eight as its president. Star joined the Ball Horticultural Company in 2015 at which time Bradd also became a member of the company’s Executive Committee and recently has been added to the Board of Directors of Ball Tagawa Growers in California and the National Plant Network in Alabama. Bradd is a proud graduate and active alumni member of the Executive Academy for Growth and Leadership (EAGL) program.
Away from work, Bradd has a history of volunteering as a youth and high school sports coach, with over 15 years dedicated to helping young people and was founding member and President of the Kent County (MD) Pop Warner organization for over 10 years.
He and his wife have three grown children. Bradd enjoys golf, hiking, and traveling with his wife to visit their children and attend Penn State Football games.
Scott Valentine
Express Seed Company
CEO
Scott Valentine is the CEO of Express Seed Company, a leading broker/distributor of horticultural genetic products in North America.
Scott has over 25 years of experience in the agriculture space—15 in horticulture. He previously held the position of President of Syngenta Flowers North America. His experience has provided him with unique insight into the needs of North America and the knowledge of the horticulture value chain—from breeding, to production, logistics, operations and sales.
He earned a B.S. in chemistry from Bowling Green State University, a Ph.D. in biochemistry from UCLA, and an MBA from the Keenan-Flagler Business School at the University of North Carolina in Chapel Hill. For the past 4 years, Scott has served as a member of the AmericanHort Advocacy Committee. He and his wife have three children and Scott enjoys golfing, hiking and cooking.
Emily Showalter
Willoway Nurseries, Inc
Chief of Human Resources
Emily Showalter is the Chief of Human Resources at Willoway Nurseries, Inc. in Avon, OH, a third-generation family-owned business and one of the largest wholesale growers of quality nursery stock in the Midwest. Emily grew up in the family business, graduated from The Ohio State University with a BS in Agriculture, completed the Goldman Sachs 10k Small Business Program, and is a graduate of the Executive Academy for Growth and Leadership. Emily served as President of the Ohio Green Industry Association in 2020 and serves on area Horticulture program advisory boards.
Brian Lloyd
Olson’s Greenhouse
CEO
Brian Lloyd is CEO of Olson’s Greenhouse, a fourth-generation, family-owned group of companies growing, distributing, and merchandising bedding plants to mass market retailers throughout the Western United States. Brian has degrees in Marketing and Ornamental Horticulture from Utah State University and an MBA from the Marriott School of Management at BYU. He is an active member of YPO International, a worldwide leadership community of chief executives, and an alum of the Harvard Business School Owner/President Management program.
Christine Fortman
Berridge Nurseries, Inc.
Third-generation owner and operator
Christine Fortman’s corporate, non-profit and political experience serves her well as a third-generation owner and operator of her family’s Arizona retail nursery that started in 1938. Since joining the nursery over a decade ago, Christine has contributed to the industry through her involvement as Past President to the Arizona Nursery Association (ANA) as well as the Independent Nurseries of Arizona and is a current board member to ANA’s charitable arm, ANAFund. Christine sees one of our industry’s greatest opportunities is the engagement and investment in the education of future generations. She meets regularly with school garden coordinators to support and enhance important projects. She has established two named ANAFund scholarships that are awarded annually to students enrolled in a horticulture related curriculum at a university, community college or continuing education program. Christine is a graduate of the University of Colorado at Boulder and participated in the inaugural class of the Horticultural Research Institute (HRI) Leadership Academy. In addition to traveling and playing golf with her husband, Stefan, she enjoys her community role with The Board of Visitors, which supports the healthcare needs of women, children and the elderly.
Lionel van der Walt
AmericanHort
President & Chief Executive Officer
Lionel van der Walt is a dynamic global executive with over 20 years of leadership experience driving growth and transformation across various sectors, including high-tech startups and international non-profit associations.
As the incoming President & CEO of AmericanHort, he brings a unique blend of operational expertise and a proven track record of delivering exceptional value to member-driven organizations.
Most recently, Lionel served as the Chief Commercial Officer at Nallian, a technology company specializing in data-sharing solutions for the global air cargo industry. Prior to his time in the tech sector, he held key C-suite roles within the association space, serving as the CEO of the International Institute of Building Enclosure Consultants (IIBEC) and as President of Cargo Network Services Corp. (CNS), a subsidiary of the International Air Transport Association (IATA).
His career is defined by a global perspective, having lived and worked in South Africa, Spain, the United Kingdom, and the United States. This multicultural background enables him to navigate complex business challenges and foster the collaborative partnerships necessary to advance the green industry. His leadership journey began with a foundational start in the South African Air Force, followed by over a decade of leadership roles at IATA spanning the Americas, Caribbean, Europe, and Southern Africa.
Beyond the boardroom, Lionel’s connection to the land is deeply personal. Having grown up in the farming communities of South Africa, where his family continues to own and operate farms, he developed an early and enduring appreciation for agriculture. This has fueled a lifelong interest in viticulture and pomology, with a particular focus on small scale almond and hazelnut production.
Lionel holds an MBA from Milpark Business School. He is a passionate champion of high-performance teams, innovation, and diversity, and is dedicated to building upon AmericanHort’s strong legacy of advocacy and growth.
Tom Fessler
Woodburn Nursery & Azaleas, Inc.
President and Co-owner
Tom Fessler, President and Co-owner of Woodburn Nursery & Azaleas Inc., oversees a diverse operation known for growing florist azaleas, annuals, and containerized nursery stock. Tom inherited his passion for the industry from his parents who established the business in 1968. Today, he jointly manages the nursery alongside his four siblings. The nursery has grown to 675 acres, with 125 acres of greenhouses, 550 acres of gravel can yards, and pot in pot operations. Tom has actively contributed to the Oregon Association of Nurseries, starting from the grassroots level on the local chapter board and progressing to the state board of directors. Driven by a desire to stay informed and engaged, Tom served on the association’s executive committee, holding the role of president for the 1995-96 term. Furthermore, he lent his expertise to the Oregon State Board of Agriculture, serving for eight years. Tom is a devoted family man. Married to his wife Debbie for 41 years, they have six children and 19 grandchildren. In his spare time, Tom attends his grandchildren’s sporting events and seizes the opportunity to take them fishing any chance he gets.
Patricia Dean
Wadsworth Control Systems
CEO
Ken Altman
Altman Plants, Inc.
Co-President
Ken Altman is the co-president of the family-owned-and-operated Altman Specialty Plants, an industry-leading breeder and grower of horticultural plants in the U.S. Altman Specialty Plants operates production nurseries and distribution facilities from coast to coast, a nationwide footprint encompassing 38+ million square feet of greenhouse space and 4,000 acres of outdoor space. Under Ken’s leadership, Altman Specialty Plants has long embraced an active role in helping achieve a sustainable present and future for its communities, from a water recycling system at the company’s largest California nursery and a floating solar array that powers its largest nursery in Texas to a growing fleet of electric tractors and autonomous pull vehicles. Ken and his wife, Deena, founded Altman Specialty Plants in 1974 in his hometown of Los Angeles as a backyard hobby that soon became a business. Ken attended undergraduate school at UC Berkeley and earned a PhD in clinical psychology in 1976 at California School of Professional Psychology. Ken and Deena have three children, including son Matt, who is co-president of Altman Specialty Plants. While the company’s reach today extends internationally, Ken maintains an active presence in the local agricultural community. He is a past president of the San Diego Farm Bureau’s board of directors and in 2022 was named the bureau’s Farmer of the Year.
Joe Allilo
Petitti Family of Farms
President
Joe Allio is the President of Petitti Family Farms, a premier 4,000-acre collection of farms—including Ridge Manor, Willowbend, Losely, and Klyn. Under his leadership, the farms cultivate a diverse selection of trees, shrubs, perennials and ornamental grasses, supplying garden centers, growers, landscapers, and re-wholesalers across the U.S. and Canada.
As a second-generation, family-owned business, Petitti Family Farms is an integral part of the Petitti family’s legacy, which also includes 10 Petitti Garden Center locations throughout Northeast Ohio.
Before joining Petitti Family Farms, Joe had a successful career spanning over 15 years in finance, including serving as a Principal at Ares Management from 2014 to 2021, where he specialized in investments within the energy industry. His earlier experience in investment banking included roles at KeyBanc Capital Markets and Stephens Inc.
Joe holds a B.B.A. in Economics and Finance from Ohio University and currently serves on the Board of Portage Country Club in Akron, Ohio.
Kent Fullmer
Chairman
President at Fullmer’s Landscaping, Inc.
Kent Fullmer is President at Fullmer’s Landscaping, Inc. in Dayton, OH, a residential landscape design and build company. Kent’s father started the business in 1962, Kent assumed ownership of the company in 2005 and continues to lead the second-generation company with passion and integrity. Kent brings high energy to the art of landscaping and his goal to provide positive personal experiences to Fullmer’s Landscaping’s clients. Kent has considerable experience working across the industry as he has served on the board of directors of the Ohio Nursery and Landscape Association, is currently serving on the AmericanHort Landscape Contractor Committee, is a certified arborist as well as a member of the International Society of Arboriculture.
Derek Clark
Vice Chariman
Director of Sales for Metrolina Greenhouses
Derek Clark is Director of Sales for Metrolina Greenhouses, a business founded in North Carolina in 1972, and is now one of the largest greenhouse operations in the world. Previously, Derek was the Director of Sales for South Central Growers, a second-generation family-owned greenhouse in Springfield, TN, that merged with Metrolina Greenhouses in 2026. He began working in the horticulture industry in 2005 and held several key account management roles before joining South Central Growers in 2013. Derek is a graduate of the University of North Carolina at Chapel Hill as well as a graduate of the Executive Academy for Growth and Leadership. He is passionate about helping strengthen the industry for future generations.
J. Harvey Cotten Jr.
Treasurer, AmericanHort
Harvey Cotten is a garden writer, designer, and consultant. After 22 years with the Huntsville Botanical Garden, most recently as vice president and chief horticulturist, he retired in 2014. He continues to present workshops for the Botanical Garden, Master Gardener Associations, Garden Clubs and other botanical gardens and arboreta while lecturing across the southeast on various garden topics. Harvey is very active in the industry. He currently serves as president of the Alabama Nursery & Landscape Association and is past president of the Horticultural Research Institute (HRI) and Alabama Invasive Plant Council. Harvey co-authored a popular book “Easy Gardens for the South” published in 2009. He earned a Bachelor of Science degree in Ornamental Horticulture from Mississippi State University. Prior to joining the Huntsville Botanical Garden staff, he was general manager of Monmouth Plantation in Natchez, MS, and co-owner of Chase Nursery Co in Huntsville.
Edward Overdevest
Immediate Past Chairman
Overdevest Nurseries LP
Ed Overdevest is the president and owner of Overdevest Nurseries, one of the leading nurseries in New Jersey where they sell to independent garden centers and distributors within a 300-mile radius of Bridgeton. Upon graduating from Cornell University, Ed returned home to become a partner in the family business, which he and his wife Gail later purchased. They led the company through a vigorous expansion and product diversification process and are proud to have their son Ryan join the team as a third-generation partner. With production facilities encompassing 290 acres, the nursery produces over 2,000 varieties of perennials, shrubs, and trees for east coast garden centers. The company has earned a sustainability certification due to their exemplary practices in conservation, and they are known for their strong labor relations and community involvement. Ed has received numerous honors including Young Farmer of the Year, Young Farm Couple, Nurseryman of the Year, Business of the Year, Grower of the Year, and several marketing awards. He has held leadership positions in local, state, and national community, business, and trade organizations.