Ninebark is a native perennial shrub that likes to be near moisture, growing to 10 feet tall on multiple stems that are frequently branched. The branches are long, re-curved, and the old bark on branches will peel in layers or strips, hence the common name "Ninebark". Young stems are green, older stems turn a darker reddish-brown.
Leaves are alternate and larger lower leaves will have 3 to 5 pointed lobes (resembling maple leaves). The overall shape is ovate to oval with coarse teeth or dentations on the margins of the lobes. Upper leaves are smaller with less pronounced lobes. The upper surface is smooth while the lower surface has some sparse whitish hair on the veins. Leaves are stalked and at the base of the stalk is a pair of very small pointed stipules. Fall color can be yellow to a purplish red.
The inflorescence is an upright rounded cluster that looks like an umbel but is technically an open hemispheric raceme of showy 1/2 inch wide white stalked flowers.
The flowers are 5-parted with a cup-shaped hypanthium that is a yellow-orange color with 5 light green triangular calyx lobes. When the flower opens, these reflex and turn whitish. The corolla has 5 white petals with rounded tips, numerous stamens with reddish anthers, and 5 styles from the ovary.
Fruit: The fruit is an inflated seed capsule (a follicle) for each flower, borne in the upright cluster, turning to a reddish brown in the fall and by that time the cluster is usually drooping. Each capsule may have from 3 to 5 chambers and when mature, the capsule splits along two sides and releases a shiny reddish tear-drop shaped seed that has a beak at one end.
Habitat: While commonly found in moist areas the shrub is adaptable to other moisture conditions with full sun to partial shade. It can be propagated from seeds or cuttings; seeds require no pretreatment to germinate; the plant can be transplanted when young. When well established however, it is well grounded and would require heavy equipment to fully remove.
Names: The genus name Physocarpus, is from two Greek words, physa, meaning "a bladder" and karpos, meaning 'fruit', in total - 'bladdery fruit' referring to the way the seed is held in a bladder like cover. The species name opulifolius, is a bit obscure and refers to leaves like the "opulus". Opulus, is taken directly from the Greek where it referred to a type of maple and was applied here due to the maple-like leaf shape. The author name for the plant classification, ‘Maxim.’ is for Karl Maximovich, (1827-1891) Russian botanist who extensively studied and wrote about the flora of the far east. His work updated that of '(L.)', which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: While somewhat resembling the Spireas this shrub is distinguished by the shedding bark and the clusters of inflated fruits. See notes below on varieties.
Above: Flowers have 5 white petals, numerous stamens with reddish anthers and 5 styles. 2nd photo - Early fruit forming in mid-July.
Below: The structure of the inflorescence is a corymb, where the flowers have stalks of different lengths so as to form a rounded or flat-topped cluster. The cup shaped hypanthium is a yellow-orange color with 5 light green triangular calyx lobes. 2nd photo - When the flower opens, these reflex and turn whitish.
Below: The lower leaves have 3 to 5 lobes while the smaller upper leaves have less pronounced lobes. 2nd photo - The underside of the leaf is a pale color with sparse whitish hair on the main ribs.
Below: 1st photo - The pair of small stipules at the base of the leaf. 2nd photo - Old bark on branches will peel in layers or strips, hence the common name "Ninebark".
Below: Plants with full to partial sun and feet not too moist can produce a deep purplish red fall leaf color. In moist areas the color is usually yellow. 2nd photo - Seed heads of late August. The inflated capsules for each flower stem have from 3 to 5 chambers.
Below: Each chamber of the inflated seed capsule releases a shiny tear-drop shaped seed with a beak at one end.
Below: For the home landscape a cultivar named 'Summer Wine' is available which, throughout the growing season, has much of the purplish fall coloring of the native plant.
Below: A Ninebark in flower. Note the arching branches.
Below: The entire shrub with mid-June blooms. This example in the Garden is a large old specimen, close to 10 feet high with a close-growing dogwood intertwined in some of the branches, so trace the branches to identify the correct plant. The bark is entirely different on the Dogwood. It is located at Guidebook station 24 at the intersection of Geranium Lane and Lady's-slipper Lane. Today, the boardwalk makes a curve around this area.
Notes: Eloise Butler's Garden records show that she introduced this plant to the Garden on April 14, 1910 with two plants she obtained from Jewell's Nursery in Lake City, MN. On April 29, 1912 she planted 2 from Gillett's nursery in Southwick, MA. This plant was listed on Martha Crone's 1951 inventory of plants in the Garden at that time. Ninebark is native to Minnesota in counties that border the eastern edge of the State, including the metro area and all of the SE corner of the State. It's overall range is the eastern 2/3rds of the United States and Manitoba eastward in Canada, excepting Labrador and Newfoundland.
Varieties: Physocarpus opulifolius is the only species of the genus found in Minnesota and is the most widespread species of the genus in North America. Some references will list two varieties of this species: var. intermedius has fruits that are covered with starry shaped hairs and var. opulifolius has fruits without hair. In the most recent update, Flora of North America (Ref. W7) does not support division of the species into two varieties. For the home landscape a cultivar named 'Summer Wine' is available which, throughout the growing season, has much of the purplish fall coloring of the native plant.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"