Menispermum canadense L.—Moonseed
FAMILY: Menispermaceae—the Moonseed Family
This mostly tropical group is not well represented in Pennsylvania. It includes twining, dioecious vines with leaves: simple, alternate, lacking stipules, palmately veined; flowers: small, inconspicuous, white or greenish, unisexual; sepals: not much differentiated from the petals, the outer series (calyx) longer than the inner series (petals); stamens: 6 (or more); ovaries: 3, separate; fruit: a drupe.
PHENOLOGY: Moonseed flowers June through July.
DISTRIBUTION: Found twining on other vegetation in moist woods, thickets and fencerows.
PLANT CHARACTERISTICS: Moonseed is a perennial woody climber, sepals: 4 to 8, longer than the 4 to 8 petals; male flowers: stamens 12 to 24; female flowers: with 2 to 4 pistils; fruit: a black drupe, with a whitish wax film at maturity; appearing in grapelike clusters; leaves: palmately veined with low, rounded teeth; leaf petioles: may be twisted at the point where they attach to the stem.
POISONOUS PARTS: Perhaps all parts of this plant are toxic, but the fruits, which hang in pendulous grapelike clusters, are especially poisonous. The rootstocks also contain bitter alkaloids.
SYMPTOMS: The symptoms of poisoning could not be found in the literature; death, however, has been reported from ingestion of seeds.
POISONOUS PRINCIPLES: Plants contain isoquinoline alkaloids, including dauricine that has curarelike activity. In fact, Amerindians use a South American member of this family, Chondodendron tomentosum Ruiz & Pav., as an ingredient in arrow poison. It is also a constituent in a muscle relaxer used by anesthetists prior to operations.
CONFUSED TAXA: The woody vine, dark clusters of fruit, and similar general leaf shape allow this plant to be confused with wild grape (Vitis L.), the fruit of which is edible. Moonseed can be distinguished from wild grape by closely comparing leaves and seeds contained in the fruit. Wild grape leaves have twenty or more blunt teeth, but moonseed leaves have fewer than ten broad, shallow, rounded lobes Grape has several slightly pear-shaped seeds within each fruit; moonseed has a single, flat. crescent-shaped (almost circular). grooved seed.
SPECIES OF ANIMALS AFFECTED: Birds appear to safely consume the fruits of moonseed plants. Because its distribution is limited to woodlands, Menispermum canadense is unlikely to be a problem for livestock. Records indicate that some time before 1935 children in Cambria County, PA, mistakingly ate moonseed fruits and died.
TREATMENT: (11a) (b); (26)