Plants that are ornamental, functional, durable and, best of all, native are hard to beat. Rubus odoratus (purple flowering raspberry) is all of these things with an agreeable nature that makes it very easy to use in the landscape – a real bonus to landscape professionals who are continually on the prowl for reliable plants that are multifunctional and ecological.
Rose-like flowers, nearly two inches across, appear profusely in early summer and continue through the season. Flowers are deep pink with a shimmery, satiny texture and a rose-like fragrance that attracts butterflies and other insects. Flowers yield to three-quarter-inch-diameter, cup-shaped, salmon-colored fruits (raspberries), which are edible but lack the sweetness and flavor of their bramble cousins. Berries are, however, highly palatable to birds and other wildlife, as well as being decorative. Deer do not prefer the plant.
Plants are self-incompatible. For best fruit set, you will need two or more plants, preferably from different sources.
Most appealing to me are the large (4- to 10-inch), five-lobed, maple-like leaves with a fuzzy texture that gives them a velvety, gray-green color. Upright, arching canes lack the typical bramble thorns and prickles, but do have glands, which have a slight sticky feel to them. This adds to the plant’s “fuzzy” appearance and unique texture.
Rubus odoratus grows natively throughout the eastern United States and the Alleghany regions. It is quite common in the Catskills where it is reportedly spectacular in bloom. It can be observed growing in thickets, forest edges and along roadsides. Its status is endangered in Illinois and threatened in Indiana, although there are native populations in the counties of Kane, DeKalb and Cook in Illinois. It can also be found growing in the West Branch Forest Preserve in DuPage County. Companions there are Jack-in-the-pulpit, Joe Pye weed, spreading oval sedge, wild plum and other denizens of the forest edge. R. odoratus will thrive in many adverse situations including wet, soggy clay, dry sun and heavy shade, although it looks best with consistent moisture favoring typical “edge of woods” conditions.
PHOTO BY JOHN MUNT, WISEACRE GARDENS
PHOTO BY PAT HOLLINGSWORTH
Name: Rubus odoratus
Common Name: Purple flowering raspberry; thimbleberry
Hardiness: Zones 3 to 8
Mature height: 3 to 6 feet
Mature spread: 6 to 12 feet
Classification: Perennial subshrub
Landscape use: Best in shade gardens, shrub borders, native plant gardens or naturalized areas
Ornamental characteristics: Rose-like, fragrant, 2-inch-wide, rose-purple flowers over a long summer period with palmate, five-lobed, maple-like, felty green leaves
A similar and related species is R. parviflorus (more accurately called thimbleberry), with white flowers and a similar culture and habit. It is common to our Western mountain regions.
Like other Rubus species, R. odoratus spreads by stolons to form mounded colonies. Unlike its cousins, the brambles, stems or canes persist from year to year. Errant stems can be removed when needed, or the entire plant can be cut back hard after flowering in order to shape or control growth. I observed a 20-year-old planting of purple flowering raspberry that still retained the appearance of four individual plants forming a single shrub mass. Adjacent plants, a gravel pathway and lawn effectively curtailed the plants’ suckering tendencies. Growth at this location, for each plant, was about 4 feet in height by 5 feet in width, with little to no maintenance. Flowering and fruiting was profuse from year to year.
Seed from this source was used for propagation purposes at The Natural Garden in St. Charles, Ill., which specializes in producing plants from local ecotype. (One needs to be aware of the importance of provenance when considering restoration work.)
Propagation is also easy from cuttings and layers. Unblemished fruit must be significantly overripe before harvesting seed. Seed can be direct sown in fall.
According to University of Delaware professor and author Doug Tallamy in Bringing Nature Home, we have been slow to realize the importance of suburban gardens to the preservation of native wildlife. Flowers are hosts for insects, which are the staple diet of many young birds as well as migrating populations. Purple flowering raspberry is a plant that can both decorate our landscape and benefit the environment.
Paw Paw, Ill.