Wild Cucumber

As its name suggests, wild cucumber, or manroot (Marah macrocarpa), is a relative of the garden cucumber, as well as watermelon and squash. Unlike its relatives, all parts of the wild cucumber plant are toxic to some degree.

The other common name, manroot, comes from the large tuberous root which may be the size and shape of a sleeping man. One root, excavated at the Rancho Santa Ana Botanic Gardens, weighed 467 lbs. The root contains a substance that stuns fish, and Native Americans “fished” by tossing pieces of pulverized roots into ponds and streams.

Description ^2,8,11,23,59

Wild cucumber is a long, branching, herbaceous, perennial vine that may reach 25 feet (8 m) in length. One or more viny stems grow from an enormous, fleshy tuber. The vines climb up and over adjacent shrubs, clinging by means of long, coiled tendrils. Leaves are palmately lobed, 2-4 inches (5-10 cm) across, with  5-7 lobes.

Flowers are either male or female; both are found on the same plant. Five to twenty male flowers occur in spikes arising from leaf axils. Male flowers are about a ½ inch (8-13 mm) in diameter.  Male flowers begin to appear before the female flowers.⁴ This helps prevent self-pollination and encourages gene flow between different plants.  The female flowers are slightly larger; they occur singly at the base of a male spike. Flowers of both sexes are similar, white to cream, shaped like a shallow cup with five lobes. The ovary is below the female flower, appearing as a spiny, pea-sized sphere below the petals. The major bloom period is December or January through April.¹

The fruit is a large, green, spiny ovoid, 1½ to 5 inches long, suspended from the vine. Spines stiffen as fruit ages. Up to 16 large seeds are formed within 4 chambers. When mature, the fruit splits open at the lower end, ejecting up to four seeds from each chamber; the attractive seeds are shiny and brown, about the size of a penny.

Plants have a very short growing season, putting forth shoots with the first winter rains. By February, vines engulf the surrounding shrubs. By mid-summer, the plant has gone dormant, leaving a characteristics tangle of dried stems over surrounding vegetation.

Classification ^2,11,34,44

Wild cucumber is a dicot angiosperm in the gourd family, Cucurbitaceae. Many members of this family are climbing vines with tuberous rootstocks. Flowers are typically in parts of five (4-6 in Marah), radially symmetrical with the petals united or partially so and either white or yellow in color. Male and female flowers are distinct, usually produced on the same plant (the plant is “monoecious”). The ovary is attached below the flower (the ovary is “inferior”). The fruit is often fleshy and melon-like with a rind and a spongy interior or woody and gourd-like.

The gourd family contains major food plants such as cucumbers, melons and squashes. These fruits were among the earliest cultivated plants in both the Old and New Worlds.

In the past, taxonomists have recognized several varieties of wild cucumber. Our plant was initially reported as a variety of macrocarpa.⁴⁸At present, these earlier varieties are no longer considered valid.^2,7

One other species in this family has been recorded from the Reserve, wild gourd (Cucurbita foetidissima).⁴⁸

Ecology  

Wild cucumber, with its large underground tuber, is one of the first plants to resprout after a fire.^14,23 It reseeds vigorously the first year after a fire and It is not uncommon to see carpets of wild cucumber during the first post-fire season.⁷⁰

Wild cucumbers climb by means of long tendrils from their leaf axes.¹³⁹ Tendrils are straight until they reach a twig or other support at which time the tip of the tendril coils quickly around the support, anchoring the vine.³⁹⁰ Subsequently the entire tendril coils between the plant and its support. Darwin recognized the paradox of a tendril coiling when anchored at both ends, and he resolved the dilemma when he noted that the tendril coils in the opposite direction from either end. Near the middle of each coiled tendril is a flat spot where the coils change direction. This flat spot is called a “perversion”. There may be more than one perversion on a coil. The coiling of the tendril shortens the tendril, winching the cucumber plant closer to its support, as well as providing an excellent spring between them.

Human Uses  

Native Americans in southern California used wild cucumber in a wide variety of ways; the high frequency of carbonized seed coat fragments at prehistoric sites suggests that many of these uses extend far back in time.⁶⁹

Kumeyaay made the ground seeds into a black paste that was used for face paint, and a topical application of leaves was used to relieve pain and inflammation.^{16, 69} The Luiseño made a grease base for paints.¹⁷ The Chumash used parts of the plant medicinally, and their children used the large, hard seeds as gaming pieces, or strung them into necklaces.¹⁵

Other tribes groups used the pulverized tuber or seeds to catch fish; when this powder was cast into rivers or tide pools, the stunned fish would float to the surface for easy capture.⁶⁹ The oil from the seeds was often used to reverse baldness; chemicals in wild cucumber have pharmacological activities similar to chemicals used in modern baldness treatments.⁶⁹

We found no records of wild cucumber being used for food. The plant contains a bitter substance and all parts of the plant are mildly toxic.⁶⁹ However, a young Hispanic man told us that his mother used to slice the very young fruits and cook them in stews.

Interesting Facts  

The common name “manroot” comes from the large tuber which, some say, resembles a man in a fetal position. A tuber dug up at Rancho Santa Ana Botanical Gardens weighed 467 pounds (excluding several basal tubers left in the ground).³⁴

The mature fruit may split open with some force, making an audible sound as it ejects the seeds. Several years ago, a green wild cucumber fruit was brought in to the Nature Center and placed on the front desk. Because it received so much attention from curious visitors, it sat there for several weeks. One morning, the Rangers arrived to find the cucumber had ejected its seeds with such force that the desk and much of the visitor center was covered with small bits of cucumber.

The genus name, Marah probably came from the very bitter taste of the roots, in reference to the bitter waters of Marah mentioned in the Bible; some, however, think it is based on an aboriginal name.²¹