Ligustrum japonicum, known as wax-leaf privet[1] or Japanese privet (Japanese: ネズミモチ) is a species of Ligustrum (privet) native to central and southern Japan (Honshū, Shikoku, Kyūshū, Okinawa) and Korea.[2] It is widely cultivated in other regions, and is naturalized in California and in the southeastern United States from Texas to Virginia.[3]
L. japonicum is an evergreen shrub or small tree growing to 2–5 meters (6 ft 7 in – 16 ft 5 in)—rarely 6 meters (20 ft)—tall, with smooth, pale grey-brown bark on the stems. The leaves are opposite, 5–10 cm long and 2–5 cm broad, glossy dark green above, paler glaucous to yellowish green below, thick and leathery textured, and with an entire margin. The flowers are white, with a four-lobed corolla 5–6 mm long; they are borne in clusters 7–15 cm long in early summer. The fruit is an oval drupe, 10 mm long, ripening purple-black with a glaucous waxy bloom in early winter; in Japan they are popularly likened to mouse or rat droppings. The species is closely related to the Chinese Ligustrum lucidum, differing in its smaller size (L. lucidum making a tree to over 10 m tall), and elongated oval (not subglobose) fruit. Flowering occurs from July to October and fruiting occurs in autumn while reproducing asexually. The plant grows in sun or shade, damp, disturbed, or undisturbed areas, commonly found in floodplain forests, wetlands, and pine flatwoods. Exotic plant invasion is considered one of the main causes of the degradation of ecosystems and loss of biodiversity globally.[4] Japanese Privet is native to Japan and Eastern Asia and was introduced to the United States from Japan and Korea in 1845. Ligustrum japonicum is commonly used as ornamental in many parts of the world. They are valued by their evergreen leaves, white flowers, adaptability to different ranges of landscape conditions, pruning, resistance to diseases, and wide availability. Some Ligustrum species have escaped cultivation and become naturalized in natural areas.[4] For example, sixteen countries report the naturalization of Chinese privet. In the United States, Chinese privet has been established in 20 states and it's considered invasive.
Lingustrum Japonicum arrived in North America in 1845 from Japan and Korea. It has become an invasive plant, particularly in the American South as it has escaped from cultivation. It is occasionally grown as an ornamental plant in Europe and North America; several cultivars have been selected for garden use, including 'Rotundifolium' with leaves nearly as broad as long, and 'Silver Star' with creamy-white margins to the leaves. It has spread to various states in the United States due to its use in ornamental horticulture. In Florida, the FLEPPC does not list Ligustrum japonicum as an invasive species but it has escaped cultivation in 11 southeastern states including TX, AR, LA, MS, GA, SC, NC, TN, and PA9. Currently, 11 different species and hybrids from the privet genius are commercially available in the US. The fruit is used in herbal medicine as a cardiotonic, diuretic, laxative, and tonic treatment. Ligustrum japonicum has different effects on osteogenic and adipogenic cells within the body. By examining the ALP activity and lipid accumulation using human bone marrow derived from stromal cells, an increase of ALP production will be found.[5] The accumulation of intracellular triglycerides are well-known markers of osteoclastogenesis and adipogenesis. The increase in ALP is due to the substances within the fruits of Ligustrum japonicum. Ligustrum japonicum fruits have been used in traditional medicinal practices and supplements in Korea and Japan.[1] It has been reported to have various bioactivities. Which is why Ligustrum japonicum is used for tonic effects in traditional Japanese medicine.[6]
Ligustrum Japonicum is a fern with twining fronds of indeterminate growth because it lacks terminal structures and its petioles continuously elongate.[7] Due to rapid root sprouting, and the use of underground rhizomes, it can grow rapidly to form a dense "wall" possibly reaching 90 feet in length, which causes the elimination of seedlings and other native plants as it shades and displaces them.[8][7] The plant has a rapid growth rate when it is young and slows down as it matures and it invades lowlands and uplands, fence rows, abandoned pastures, intermittent stream beds, and woodlands. It also is problematic in plantations as it contaminates them and causes problems in the pine straw industry.[9] It also disrupts natural and prescribed fires as its growth creates a ladder that fuels fires and allows for the fires to reach into the tree canopies. It has been found that local fires and planned fire aid in the spread of Japonicum, especially in mesic pine savannas, due to their ability to survive the fires with their rhizomes which allow for spore production and dispersal in the surrounding herbaceous ground cover post-fire. It is distributed by birds eating the fruit and is propagated by cutting, seeds, and honeybees. Its tiny spores are also dispersed by the wind, clothing, equipment, and vehicles. Ligustrum Japonicum is an intragametophytic selfing fern, using two gametes from the same haploid gametophyte to form a complete homozygous sporophyte.[7] Therefore Ligustrum Japonicum only needs a single spore to create an entire fern population. The plant is also poisonous to humans, cats, dogs, and horses. It causes abdominal pain, nausea, vomiting, diarrhea, headache, weakness, low blood pressure, and clammy skin in humans.
Ligustrum japonicum invasiveness can be controlled by mechanical, biological, or chemical methods. Mechanical control includes using machinery to remove large mats of foliage that form over any vegetation or by hand pulling the young seedlings before their rapid growth begins. The possible biological control agent that can be utilized is the rust of the plant known as Puccinia lygodii in greenhouses but more studies need to be conducted to know its effectiveness.[9][10] The plant can also be controlled chemically by the use of glyphosate, imazapyr, and metsulfuron-methyl, which are all herbicides that inhibit the formation of amino acids in the plant.[10] Many ornamentals gain invasiveness through their prolific production of viable seeds. Therefore, making plants sterile or seedless can reduce, even eliminate, their invasive potential.[4] Several genetic tools have been used to reduce seed production, viability, and germination.[10] This includes natural mutation, artificial mutagenesis, interspecific hybridization, ploidy manipulation, endosperm culture, and transgenics.[4] Ploidy manipulation has proven to be successful and yields multiple sterile, noninvasive cultivars or breeding lines in a variety of ornamental plants.[4]
Ligustrum japonicum, known as wax-leaf privet or Japanese privet (Japanese: ネズミモチ) is a species of Ligustrum (privet) native to central and southern Japan (Honshū, Shikoku, Kyūshū, Okinawa) and Korea. It is widely cultivated in other regions, and is naturalized in California and in the southeastern United States from Texas to Virginia.
