Plant Profile: Manroot (Marah)
Since early January, I had been watching this cute little vine weave its tendrils around plants on Mt. Sutro, sometimes overwhelming other natives. When I was asked to do a profile on Manroot, I reacted like the typical newbie and said, “Huh?” It looked like this was one native that didn’t need any help from us, no siree! Well I’ve now been set straight by those in the know. Here’s the skinny on this vigorous native.
Manroot, also called Big Root or Wild Cucumber is of the genus Marah, a Hebrew word meaning bitter. It is a flowering perennial in the gourd family Cucurbitaceae (pronounced cue-kurbi- tay’-see) and is native to western North America and British Columbia. It grows from a large tuberous root, which according to some accounts, can take the shape of a man, and weigh up to a hundred pounds.
Marah fabaceus (California Manroot) and Marah oregana (Coastal Manroot) are two of the species found here on Mt. Sutro. They can be seen growing happily alongside non-native English Ivy and Cape Ivy, which explains why some people mistake Marah for these non-natives. Pictured right, Marah growing with English Ivy. A big difference between the native Manroot and similar-looking invasive ivies is that other plants do not appear to be adversely affected by Marah clambering over or growing intertwined with them. The Manroot dies back at summer’s end and does not appear to strangle other plants as it does so. Unfortunately, the same can’t be said of the invasive ivy plants that cover much of the mountain.
Flowers on the Manroot are usually white, but can vary in color from yellowish green to cream. The flowers are monoecious, meaning, they are either male or female, but both are found on the same plant. Male flowers can fertilize the female flowers via insect pollination. Fruits are 2-3 inches long, round or oval, light green and covered with stiff prickles (pictured left). They form in spring and ripen in summer. To identify Marah, look for its large somewhat textured leaves and long-reaching thin tendrils that seem to be seeking something to grasp onto. Cape Ivy which is similar in coloring has smoother more pointed leaves, and English Ivy may appear with fewer points and can be darker green in color.
Native Americans were reported to have multiple uses for Manroot. Marah oregana was used by the Chinook to make a poultice from the gourd. The Squaxin mashed the upper stalk in water to dip aching hands. The Kumeyaay crushed tubers of Marah fabaceus, and tossed them on surface waters to immobilize fish. All parts of the plant have a bitter taste (hence, the genus name Marah, from the Hebrew). The liquid inside the fruit is an eye irritant, and the spines on the fruit can be irritating to the skin, so caution is advised when handling the fruit. Coastal Manroot grows well by streams or in washes but also does well in drier areas, and as high up as 1600 meters (almost a mile). It will tolerate a variety of soil types and acidities, and will grow either in full sun or deep shade.
References: 1) The Jepson Manual of Higher Plants. Univ. of California Press; 1993 2) Wikipedia: Marah fabaceus; Marah oregana 3) Calflora Taxon Report 11823; http://www.calflora.org/cgi-bin/species_query.cgi?where-taxon=Marah+oregana 4) COSEWIC Assessment and Status Report on the Coast Manroot Marah oreganus in Canada; 2009.