Masses of white flowers are a common and beautiful sight along Connecticut’s roadways and in fields this time of year (late May through June). While there are (of course) many shrubs and trees bearing white flowers, one of the most predominant is multiflora rose (Rosa multiflora). This rose is native to Japan, Korea and parts of China and has become invasive throughout eastern North America. While it is invasive and is a real problem, we’re sort of stuck with it overall so go ahead and enjoy the gorgeous blooms. Photo: J. Allen, UConn
Multiflora rose was first introduced into the U.S. as early as 1866 for use as a rootstock for ornamental roses. In the 1930s, the U.S. Soil Conservation Service began to recommend it for erosion control and as a ‘living fence’ for livestock. In the 1960s plants were even distributed to landowners for free to encourage planting as cover for wildlife including birds and rabbits and as a food source for songbirds. Thanks to the songbirds, many seeds have been distributed to new sites because they do like to eat the nutritious rose hips (fruit). The plant is now considered a noxious or invasive weed in many states including in Connecticut “…prohibited from importation, movement, sale, purchase, transplanting, cultivation and distribution under CT General Statutes §22a-381d”.
Photo: J. Allen, UConn
It’s pretty easy to recognize multiflora rose when it’s in flower but also once the bloom period is over. Flowers are borne in clusters of mostly white but sometimes slightly pink flowers that are ½ to 1” across and have five petals. Leaves, too, are distinctive. They are alternate and compound, having 5-11 oval leaflets with toothed margins. The base or petiole of the leaf is fringed. Even the thorns are unique to this species. They are large, curved backwards and have an oval base. If a thorn is removed, it will leave a visible oval scar on the stem. They’re pretty serious thorns and are reported to be capable of puncturing tires and leaving a painful gash in skin. Overall, this plant can reach a height of about 15’ with long, arching stems. It can also be a climber and at times you will see it spreading up against other vegetation or structures. For some great info and photos of the thorns, fringed petals (stipules), and more check out this web page: http://na.fs.fed.us/spfo/invasiveplants/factsheets/pdf/multiflora-rose.pdf
Multiflora rose spreading through a natural area and up another tree in the background. Photo: J. Allen, UConn.
Reproduction is by seeds (prolific at 500,000 to a million seeds per large bush per year), suckers and by rooting at the end of stems that arch over and touch the ground. Widespread dispersal is via birds that eat the fruit and expel the seeds. It’s reported that seeds which have passed through a bird’s digestive system germinate more readily. Invasiveness is enhanced by not only the huge potential for seed production but also by the fact that the seeds can remain viable in the soil for up to 20 years.
Like other roses, the hips and other plant parts (leaves and flowers) are edible. The hips are high in Vitamin C, carotene and essential fatty acids. It’s recommended to harvest after the first frost when berries are softened and sweet. They can be eaten raw but do contain some hairs between the flesh and the seed that can cause irritation. Leaves, flowers and hips can be used to make tea. To make rose hip tea, mash the fruits and steep in hot water. Leaves are best when young as the hairs on the undersides can become stiffer and less palatable later in the season.
Some of the broader impacts of this plant, like other invasives, include displacement/replacement of native plants and the resulting impacts on habitat and food supply for native wildlife. Pasture lands are adversely affected when these thorny plants encroach and reduce forage area for livestock. Even forestry operations are affected because of the impenetrable, thorny thickets that form, reducing access and making work difficult. Multiflora rose can thrive in a wide range of habitats from open sunny sites to woodland edges. It can survive on a range of soil types but is not found in extremely dry or wet sites.
Control methods used include physical or manual removal including mowing, digging, and prescribed fire. Chemical herbicides can be used as either a cut stem (fall) or foliar application. Biological controls are not yet available. A virus that causes rose rosette disease limits growth in some areas but that also affects ornamental roses. An insect, the European rose chalcid, is being studied for potential use.
By J. Allen