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Multiflora roses grow in dense clusters that can become invasive

Common Name: Multiflora Rose, Japanese rose, Seven-sisters rose, Baby rose, Multi-flowered rose, Qiang wei (Chinese meaning ‘fern-like wild rose’) – The multitude of individual, fragrant
white florets on prickly arching stems is a distinguishing feature of this Rose family member.

Scientific Name: Rosa multiflora – Same as above in Latin.

Potpourri: It is counterintuitive to think of a rose as a pest, but the invasive weediness of the Multiflora Rose belies customary cultural associations. As a rose, it has all of the favorable attributes that rosarians admire: not one but up to a dozen delicately scented flowers that attract bees and butterflies, fruiting rose hips that attract and sustain birds and a generally handsome presentation as an upright understory bushy shrub that would grace any garden pergola. It is also a rose that propagates sub rosa. Each of the many flowers produces myriad seeds; an average plant produces about one million annually that remain viable for up to twenty years. The seeds are unwittingly but inexorably transported for miles by a wide variety of birds that consume the hips in which they are embedded, depositing them in a dollop of nutrient filled excrement to enhance germination. The multiflora rose reproduces not only by seed but also by rooting from the tops of the stems where they extend to the ground, creating dense thickets that choke out competing native plants. It has been declared a noxious weed in ten states including Maryland and Virginia.

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The delicate beauty of the individual rose flower
The Multiflora Rose is a native of Asia, primarily eastern China, Korea and Japan where it fills an ecological niche constrained by native arthropods and fungi. As a hardy and admirable rose, it was introduced to North America on many occasions by eighteenth and nineteenth century horticulturalists whose livelihood was in part dependent on foreign exotics. It was listed in the 1811 catalogue of the Elgin Botanic Garden in New York, so it is reasonable to assume that it has been here ever since the colonies became the United States. For well over a hundred years, it was just what it was intended to be, an enticing, exotic Japanese rose that graced the gardens of the gentry. It joined a veritable bouquet of roses, both foreign and domestic
.

The Rose order Rosales, though small in number with only 3 families and about 3,000 species, is substantial in cultural impact. In addition to the flowering
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The native Virginia Rose
bushes of the genus Rosa, there are the apples of Malus, the pears of Pyrus, and the peaches, apricots and plums of Prunus, to say nothing of the ubiquitous blackberries and raspberries of Rubus. While the many fruits of the order provide nutrition, it is the roses that capture the imagination of poesy in their delicate beauty and ambrosial scent. The Gertrude Stein quote “Rose is a rose is a rose is a rose” conveys its meaning of identity only because of the singularity of the rose. According to the Biota of North America Program (BONAP), there are 82 species of roses that are either native or grown in gardens from which they have sometimes escaped. The two most common native roses found in the mid-Atlantic region are the pink Virginia rose (R. virginiana) and Carolina or Pasture Rose (R. carolina). Worldwide, there are about 8,000 cultivars that have been officially registered. The addition the Multiflora rose to the North American bouquet was one of many such introductions; its

propensity to spread was not known nor expected.

In the middle of the nineteenth century, the hardy growth, dense thicket forming characteristics, and abundant fruits of Multiflora rose became manifest to agricultural agents seeking to remediate rampant land erosion. In the 1930’s, the U. S. Soil Conservation Service began to promote its use and many states followed suit. Multiflora rose was subsequently planted as a living fence that provided barrier control for livestock, a well-rooted anchor for topsoil, and an abundant source of food for migrating birds. For example, more than 14 million seedlings were planted in West Virginia alone between 1940 and 1960; it is still planted for field fencing in Delaware. The combination of monoculture hedgerows of the nutritious Multiflora rose hip fruits that blocked out many other potential avian food sources and hungry birds resulted in an invasive spiral of more rose hips eaten by more birds creating more bushes. The brambly intruder now occupies over 45 million acres in the eastern United States, an area larger than Virginia. West Virginia and Maryland combined. The West Virginia metrics are again demonstrative in economic cost; the 90 thousand acres infested would cost an estimated 50 million dollars to remediate. The ecological problem of invasive species is complex, extending beyond the visible cascades of vegetation to the heath of the entire system. As pointed out by Tallamy in “Bringing Nature Home,” one of the more insidious effects is that non-native species are not palatable to native insects. While this may seem innocuous and even beneficial (who needs bugs?), insects are vital to the food chain of forests and fields. Birds need not only sugars for energy, which they surely obtain from the copious Multiflora rose hip seeds, but also proteins to grow eggs and nurture their fledglings. This they get from insects. A healthy forest is a buggy one, with well eaten plant leaves as testimonial. While Multiflora rose is certainly one of the most prolific, it offers its own solution. Unlike many other non-native invasive plants whose unchecked growth threatens the very survival our fields and forests, natural biological controls of the Multiflora rose have apparently been unintentionally introduced from Asia to augment a few native predators to potentially turn the tide in favor of diversity.

The two predominant biological controls for Multiflora rose are the rose seed chalcid (Megastigmus aculeatus) which is a small wasp introduced from Japan, and a Native American virus called rose rosette disease (RRD). The chalcid wasp was first reported in New Jersey in 1917 and it has since become well established in the Mid-Atlantic States; a 1965 survey of the Patuxent National Wildlife Refuge near Greenbelt, Maryland found that 95 percent of the Multiflora roses were infested. The chalcid wasp lays eggs in the ovule of the flowers just after the petals fall in June; the larvae hatch in August and eat the hip fruits, killing the seeds. In an ironic twist, the birds that eat the rose fruits inadvertently transport the seed chalcid larvae to new locations as they pass through the birds’ gut thus spreading the biological control agent along with each potential new growth. Research has demonstrated that infesting 3 percent of the Multiflora rose bushes in a test plot resulted in a chalcid infestation rate of over 77 percent in one year. While the virus that causes RRD is native to North America, it is strongly opposed by the American Rose Society as it also infects many ornamental roses. It results in the abnormal growth known generically as “witches’ broom” which eventually kills the plant. A five year trial conducted in Indiana revealed that RRD killed 88 percent of the plants in an average of 22.4 months. All things considered a success story in the making.

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Rose hips entice avian distribution
Rose hips or haws are actually hypanthia, an enlargement of the cup-shaped receptacle that holds the stamens, petals and sepals that surrounds the achene seeds, an adaptation to attract birds and mammals to eat and spread the seed. The word hip is derived from the Middle English word hepe meaning bramble and is unique to the rose as a “berry” type; a hip is defined as a hollow,leathery receptacle containing many seed-like fruits. A true berry has seeds embedded in pulpy flesh like the grape; the term is used generically to include drupe, pome, hip, accessory (strawberries) and aggregate fruits in addition to the ‘true berry.’ Rose hips have been collected and used in a variety of comestibles for millennia, the result of the floral fragrance that would pique interest and inspire experimentation. This would have had a profound effect on the general health of native populations; rose hips are rich in Vitamin C which is now oft prescribed in large doses to ward off malady. The recommended daily allowance (RDA) of vitamin C is about 70 milligrams; a pound of rose hips has 100 times that amount; three hips have the same amount of ascorbic acid as an orange. Most northern hemisphere cultures use rose hips in addition the petals and other plant parts as a healthful, aromatic, if a bit acidic tisane.