Canada Moonseed is a native perennial twining vine, without tendrils, whose stems can grow to 6 to 10 feet long. Stems can be green to maroon with leaf stalks and flower panicle stalks frequently a deep maroon-like color.
The leaves are large, broad, ovate, shallowly lobed, no teeth, that are alternate on the vine on thin short stalks. These stalks are attached inward from the base of the leaf (peltate) as though the leaf were held as a shield, but sometimes the attachment point may be quite close to the base. The base of the leaf varies from truncated to slightly heart-shaped. Lobes number 5 to 7, with the leaf tip varying from pointed to obtuse.
The inflorescence is an axillary branched dense cluster (a panicle) of stalked flowers beginning bloom by early June.
The flowers are very small and have a bell shaped calyx with 5 to 8 greenish-white sepals that are ovate to elliptic in shape. These are longer than the petals, which can number 4 to 12, and are whitish in color, ovate to elliptic in shape. Moonseed is monoecious, with the flowers separated by sex with the sexes in separate panicles. The male (staminate) flowers having 12 to 36 stamens, with distinct filaments and yellowish anthers. The female (pistillate) flowers have 2 to 4 pistils with stigmas that are slightly lobed, along with 6 to 9 false stamens (staminodes). Flower stalks have very small bracts.
Seed: Fertile flowers produce a small drupe, black to bluish black, 8 to 13 mm in size, resembling small 1/4 inch grapes but should not be eaten as there are mildly toxic. The name "Moonseed" refers to the pit-like seed which resembles a flattened quarter moon, one in the center of each drupe. It is hard, with a ribbed or warty surface.
Habitat: Common Moonseed grows from rhizomatous root system in deciduous woods, thickets, along streams, fence rows, etc where there is some sun during the day, moist to mesic conditions and somewhat rich soils. It is tolerant of shade but flowering will be much reduced. Its greatest growth is when it has an object to climb on such as a fence.
Names: The genus name, Menispermum, is composed of two Greek words - mene, referring to 'moon' and sperma, referring to 'seed'. The species name, canadense, refers to 'of Canada'. The author name for the plant classification - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: There will be little confusion of this plant with others in the flowering stage but when fruit is on the vine, one must be careful to not mistake the bluish-black drupes for the edible Wild Grape of Vitis riparia.
Above: Male Flowers: 1st photo - A single male flower just opening. 2nd photo - An entire cluster. Flower have from 12 to 30 stamens.
Below: Drawing ©Flora of North America
Below: 1st photo - Leaves have 5 to 7 lobes (somewhat maple shaped). Note the leaf stalk is attached inward from the base of the leaf. 2nd photo - The underside of the leaf is paler in color due to very fine hair with longer hairs on the veins and leaf stalk. The leaf-stalk attachment point is usually inward from the base of the leaf (known as 'peltate') as though the leaf were held as a shield.
Below: The 1/4 inch diameter drupes within which is a flattened moon-shaped hard seed with a ribbed edge. This shape provides the name for the plant. Diagram courtesy USDA-NRCS Plants Database.
Below: A panicle of male flowers. Note the maroon color panicle stalk.
Notes: Canada Moonseed is indigenous to the Garden. Eloise Butler noted it in her log on May 25, 1907 and then brought in more with plants collected right in Glenwood Park on May 31, 1907. [Glenwood Park surrounded the Garden area and is now named Theodore Wirth Park] She planted an additional plant in 1909 and on July 17, 1910 found that the plant already existed in another part of the Garden and found more on Aug. 14, 1912. That did not stop her from importing another from Minnehaha Park on Oct. 2, 1917, from Glenwood Park in 1919 and from Ft. Snelling in 1920. When the Upland section of the Garden was developed after 1944, Martha Crone planted Moonseed in 1946 and in 1947 along the fence where it still grows today.
Canada Moonseed is native to a broad range of counties across the state with scattered exceptions and absent in the Arrowhead. In North America it is found in the eastern half of the continent except for Louisiana in the south, Maine in the north and in Canada it is known in the Provinces of Manitoba, Ontario and Quebec.
M. canadense is the only species of Menispermum found in Minnesota or North America. One other species exists in Mexico and one in Asia - total of 3 worldwide.
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"