Downy rose myrtle (Rhodomyrtus tomentosa), native to Asia, is spreading unchecked in Florida, taking over the understory of native pinelands, and probably altering the natural fire regimes of southern Florida. Introduced as landscaping plants, heavy infestations of downy rose myrtle already occur in several central and southern counties, including Lee, Palm Beach, Broward and Dade Counties, and as far north as Pasco County. It also occurs as an invasive weed in Hawaii.
Relatively little is known about the biology and control of downy rose myrtle. The fast-growing plant spreads by seed drop and research shows that it does not spread vegetatively. It is also spread by birds and mammals, which consume its many blueberry-like fruits. The plant can withstand slight freezes and low salinity. Apparently “fire-adapted”, downy rose myrtle resprouts prolifically after fires. Some humans reportedly harvest the fruit to make jam.
Downy rose myrtle is an evergreen shrub that usually grows to 6 feet tall, but occasionally to 12 feet tall. It can grow into large monocultures. Its leaves are opposite, simple, entire, elliptic-oval, to 3 in. long. The leaves are glossy green above and densely soft-hairy below, with 3 main veins from blade base. Downy rose myrtle flowers profusely in the spring. The flowers are rose-pink, to 1 in. across, in one-to few-flowered clusters at the leaf axils. The fruit is a bluish-purple globose berry about 1/2 in. across, that looks similar to blueberry but more oblong.
View more information and pictures about downy rose myrtle, as contained in the Langeland/Burks book, Identification & Biology of Non-Native Plants in Florida’s Natural Areas.
University of Florida researchers areinvestigating Rhodomyrtus tomentosa’s role in Florida ecosystems, especially its
seed germination and life history (flower, fruit and seed set phenology), and how it reacts to fire.
View the herbarium specimen image from the University of Florida Herbarium Digital Imaging Projects.
Financial support for this web page provided by the St. Johns River Water Management District (FL).