Ornamental Invasive Plants in Florida with Research-founded Alternatives

Abstract

The ornamental horticulture industry has long been significant in its vast economic contributions to the US agricultural sector, with Florida ranking second in nursery and greenhouse plant sales. A small proportion of introduced plants eventually escape cultivation and become invasive, leaving fragile ecosystems at risk. In response, a series of propagation and production research studies have been conducted over the years to 1) evaluate the female sterility and landscape performance of cultivars and/or hybrids of ornamental invasives, and 2) develop reliable propagation systems of novel or underused natives having ornamental and ecological value. Attractive, fruitless selections of popular species such as butterfly bush (Buddleja sp.), heavenly bamboo (Nandina domestica), Mexican petunia (Ruellia simplex), lantana (Lantana strigocamara), trailing lantana (Lantana montevidensis), privet (Ligustrum sp.), maiden silvergrass (Miscanthus sp.), and fountain grass (Pennisetum sp.) have been identified as suitable non-native alternatives to the invasive or potentially invasive resident species (wild type). Simultaneously, researchers have taken a closer look at native plant alternatives that may offer similar aesthetic traits as invasive plants, while bringing added biodiversity and function for more ecologically friendly landscapes and gardens. As such, successful multisite trialing and/or propagation systems have been developed for a number of species native to Florida, such as squareflower (Paronychia erecta), coastalplain honeycombhead (Balduina angustifolia), wireweeds (Polygonella sp.), blue porterweed (Stachytarpheta jamaicensis), wild coffees (Psychotria sp.), sweet acacia (Vachellia farnesiana), and wild lime (Zanthoxylum fagara). With pronounced marketing and consumer education, it is hopeful that together sterile cultivars and native species will ultimately replace wild-type forms of commercially available ornamental invasives. This paper summarizes the current status of ornamental invasives in Florida and the role of native species and sterile non-native cultivars.

Landscape and Fruit Evaluation of Three Privet (Ligustrum sp.) Cultivars in Florida

“…Three privet cultivars, 'Sunshine', 'Variegatum', and 'NCLX1', finished in 11.4 L pots, were evaluated in this study, as described in Table 1 [2]. Before planting, the beds were slightly disked and covered with black semipermeable landscape fabric (Lumite Inc., Baldwin, GA, USA).…”

“…Although most introduced ornamental plants do not escape cultivation, some plants spread into natural areas, develop self-sustaining populations, and subsequently disrupt the function and form of natural ecosystems [1]. In the past decade, significant progress has been made by the ornamental plant industry to minimize the risk of invasive plant introductions [2]. Voluntary codes of conduct have been adopted nationally by botanic gardens and the horticulture trade to help reduce the pathway of invasive plants [3].…”

“…Simultaneously, plant breeders worldwide have been looking for and developing new cultivars with significantly reduced or eliminated invasive potential that can replace invasive ones [4]. For example, sterile cultivars have been developed for popular landscape plants such as heavenly bamboo (Nandina domestica) [5], Mexican petunia (Ruellia simplex) [6], and lantana (Lantana camara) [7], providing safe alternatives for landscapes and gardens, with large commercial companies such as Ball Horticulture and Proven Winners now incorporating these non-invasive traits into their marketing campaigns [2].…”

“…Cultivars of invasive plants are also considered invasive in Florida unless exempted from the noxious weed ruling or proven otherwise through an Infraspecific Taxon Protocol (ITP) assessment [2]. Wilson et al [11] evaluated 12 privet selections in northern and southern Florida and found low or no fruit production among cultivars (with novel traits and/or foliage color) compared to their respective wildtype or resident taxa.…”

Plant This Not That: A Tool for Improving Invasive Species Identification and Expanding the Use of Sustainable Alternatives in Florida, USA, Landscaping

“…The ornamental plant industry serves as a significant conduit for the global movement of invasive plants, with these species contributing substantially to inventory and revenue (Bechtloff et al 2019). The scarcity of accessible resources to assist homeowners and landscapers in identifying invasive species and choosing sustainable alternatives intensifies the issue of invasive plant spread in Florida, USA (Wilson and Deng 2023).…”