Uses
Hopbush produces highly durable and tough wood, making it useful for many applications. Everything from walking staves to weapons to building materials can be made from hopbush wood. The wood of the hopbush used in many locations for firewood. Hopbush fruit has been used widely as a substitute for hops in the production of beer. The leaves may be used for their scent, and in some regions of the world are used as incense for funerals. In New Zealand, the Maori use hopbush wood for making walking sticks, spears, ax-handles and weights for drill shafts. In Brazil, Hawaii, New Guinea, Southeast Asia, and West Africa they use the wood for beams and posts used to build houses and storage buildings. Hawaiians use the red flowers to fashion leis and to make a red dye. In New Guinea, fishermen use hopbush wood to build fish traps. Hunting tribes have used the saponin-rich leaves of the hopbush in streams and lakes to stupefy fish. The sticky resin produced by the leaves of the hopbush make it possible to use its branches like a torch. Hopbush has a myriad of medicinal uses around the world. The juice of the hopbush is particularly rich in tannin, making it useful medicinally as a styptic, to heal wounds, treat rashes and soothe insect bites. Leaves may be chewed to abate toothache pain. Hopbush is used In Africa and Asia to treat digestive complaints, infections, rheumatism, and respiratory problems. In New Guinea, it is used to stimulate lactation in mothers and as a remedy to treat dysentery.
Distribution
Hopbush has what is known as a cosmopolitan distribution, meaning it can be found in many regions of the world. Locations that have a tropical, subtropical, or warm temperate regions may be home to this species. In addition to the many locations that hopbush is native to, it is also widely cultivated. Native regions include a wide distribution in Africa, as well as temperate regions of Asia including China, Iran, Iraq, Japan, Taiwan, and Saudi Arabia. Hopbush is native to tropical Asia regions including India, Indonesia, Malaysia, Myanmar, Pakistan, Papua New Guinea, Philippines, Sri Lanka, Thailand, and Vietnam. In North America, hopbush is native to Arizona, California, New Mexico, and Florida as well as Mexico. In South America, it is native to Argentina, Belize, Bolivia, Brazil, Chile, Colombia, Ecuador, Guatemala, Honduras, Nicaragua, Peru, Panama, Suriname, Uruguay, and Venezuela. The hopbush is found throughout the Caribbean as well as the Pacific islands of Fiji, French Polynesia, Guam, Hawaii, Samoa, and Tonga. It is also native to Australia and New Zealand.
Latin Name
The botanical name for hopbush is Dodonaea viscosa. The genus name of Dodonaea was given in honor of Flemish royal physician, botanist, and professor, Rembert Dodoens. The species name of viscosa is derived from the Latin term viscosus, which means sticky, a reference to the sticky exudate produced by the leaves of the hopbush.
Common Names
Hopbush is the most widely used common name for this species. That name was coined by European settlers to Australia who used the plant as a substitute for hops in brewing beer.
Preferred USDA Hardiness Zones
Hopbush is a warm climate shrub and is recommended for USDA hardiness zone 9 through 11. It is not tolerant of frost conditions.
Size and Shape
Hopbush is most often grown as a perennial shrub but can assume the form of a small tree that will grow from 4 to 20 feet in height. Typical specimens in the United States reach 12 to 15 feet in height and spread, assuming an attractive rounded shape. The shiny narrow leaves give the shrub one of its common names, varnish leaf. The seven subspecies of hopbush are primarily distinguished by their size and shape, as described previously.
Exposure
Hopbush will tolerate some shade but does best in full sun. It thrives even in arid conditions and is forgiving of poor soil and rocky terrain. A tolerance of salt spray and sandy soil makes this species popular for coastal regions. Hopbush is not tolerant of frost, requiring a warm temperate climate.
Foliage/Flowers/Fruit
The foliage of the hopbush will vary based on the subspecies. Generally, the leaves are obovate to lanceolate, ranging from two to four inches long and up to a half-inch across. They are bright green in color, often pointed and are alternate on the branches. The texture of the leaves is leathery but pliable. The leaves secrete a resin that makes them quite shiny as if they have been polished or varnished. Blooming occurs in the spring when the flowers are growing at the ends of the branches. Although some plants contain both sexes, most bear only male or only female flowers. In these cases, plants of both sexes are required for reproduction. Pollen from the flowers is transported by the wind rather than insects, a process known as anemophily. It is believed that the flowers lack petals to enhance the pollination process by exposing the pollen directly to the wind. The flowers develop in bunches of small greenish balls on slender stalks close to the branches. Male flowers have 10 stamens. Female flowers have a pistil with an ovary and four dot stigmas. Once they are pollinated, the female flowers produce three to four papery winged capsules that each contains two to three small black seeds. As the fruit matures the capsules turn red or purple to brown in color. The seeds are very small–there are approximately 84,200 seeds per pound of seed.
Design Tips
Because of its tolerance of salt and sandy soil, hopbush is useful for dune stabilization. It is also used for restoring degraded lands and for reforestation. The fast growth of this species, coupled with a tolerance of strong winds, makes it a good choice as a hedge or windbreak. Hopbush is also useful for landscaping due to its lush green foliage. It can be grown as a small patio tree, as an accent plant, or even as a container plant. They may be grown on a trellis.
Growing Tips
Once hopbush is established it requires relatively little care. Water once a month, more often if particularly dry, but do not overwater. The growth of this species is impacted by the volume of water available. If watered lightly it will remain a shrub of 6 to 8 feet in size. When more water is available, it will grow to 15 feet or more. A monthly foliar feed with a water-soluble fertilizer diluted to one-half strength will promote more robust growth. Apply a balanced slow-release fertilizer with minor elements twice a year. Hopbush may be grown from seeds; however, the seeds must be soaked in hot water to improve the germination rate. Cover the seeds with water that has been brought to a boil and allow them to soak for 24 hours. Discard any seeds that float. Plant in pots and keep the soil moist. Germination takes two to four weeks. Propagation may also be achieved via cuttings taken from healthy unstressed plants. Cuttings should be from branches that do not have flowers or fruit. Make four- to six-inch-long cuttings from branches that are 1/8 to 1/4 inch in diameter. The application of a rooting hormone is recommended. Plant the treated cuttings in a moist, sterile medium and keep them moist. Cuttings should root in four to six weeks.
Maintenance and Pruning
Hopbush does not require pruning and can be allowed to grow to a natural shape and size. However, pruning will encourage thicker growth. Prune after fruiting occurs to maintain desired shape and size, but do not prune into old wood. If desired, hopbush may be pruned into a topiary shape, as a hedge, or espaliered on a trellis or wall. If a tree shape is desired, prune to a single trunk.
Pests and Diseases
Hopbush is susceptible to a virus known as ‘Dodonaea yellows’. The disease causes stunted yellow leaves, hence the name. It is also accompanied by distortion of leave margins and internodal elongation of branches in twigs that produces a condition known as witches’ brooms. Flowering and fruiting may be reduced or completely absent on the affected branches. In some cases, the entire plant is affected, while in other cases the virus only attacks some branches. Ants, scale, and sooty mold are sometimes problems with this species. If not promptly controlled, mealybugs can be a problem as well as black twig borers. Watch for dying twigs or ends of the branches and treat with an insecticide containing imidacloprid as needed.
