Momordica rostrata (2019)

By Barbara Wedler (September 2019)

I was the lucky winner of the “show-worthy” prize plant, a specimen Momordica rostrata, at the July meeting. This species is native to dry areas of East Africa (southern Ethiopia, Somalia, Kenya, Tanzania and northeast Uganda). These plants have large caudices and grow at the bases of other shrubby plants in dry grasslands, wooded grasslands and woodlands (acacias and commiphoras) or along river banks.

M. rostrata live at elevations from sea level to 5,400 feet. They are not endangered. They are most common in Tanzania and Kenya. They were first described by Phillip W. A. Zimmermann in 1922.

Momordica rostrata is in the Cucurbitaceae family along with familiar plants such as cucumbers and squash. The plants have a large root caudex, which stores water during the dry seasons. The caudex is mostly exposed above ground. The color of the caudex can be green or green with a layer of light brown skin on parts of the caudex. The caudex shape is irregular. The caudex on the plant I won measures 6 inches tall and about 5.5 inches wide. In habitat, M. rostrata can grow to over 2 feet tall.

The species has long, thin, vining stems that grow out of the top of the caudex and can reach up to 23 feet long. Using tendrils, the stems wrap around the branches of the plants they are growing near. M. rostrata can suffocate the “host” plants with its dense vines and leaves.

The leaves have three leaflets and usually two or three sub-leaflets. The leaf edges are wavy. They are glabrous (free from hairs), but not shiny.

On my plant, the leaves are about 4 inches long. When I got the plant, it was just starting to have stems. Since that time, I see nice growth. I will have to give the stems some support so they do not attack any of my other plants.

The flowers of Mormordica rostrata are yellowish or light orange with a purple center. The flowers are not large – about 2.5 inches across for male flowers and smaller for female. The plants are dioecious, which means that a single plant will have either male flowers or female flowers, but not both. However, in cultivation, the plants sometimes are monoecious.

The seeds are flat and brown. The fruits are bright orange-red, 1 to 2 inches long. They have a pointed end that resembles a horn or beak, hence the name rostrata for the Latin word for beak, “rostro.”

The fruits have a yellow pulp that is edible, raw or cooked. The roots are toxic, but have some medical uses, including treatment for diarrhea and malaria. The dried, powdered roots are used to kill a pest called the stem borer.

The caudex of my plant was damaged when I got it. A large area on the base and underside of the caudex was rotted. This created a concave area of the caudex. I unpotted the plant and did my best to remove any remaining rotting material. I let the plant remain unpotted for a few days, then repotted it with the damaged area above the soil line in the hopes that it will be OK. I will see.

These plants are summer growers. In fall, they go dormant, lose their leaves and have some stem die back. They need ample water in the summer growing season. They should be planted in well-draining soil. Very little water should be applied in dormancy.

Propagation is by seed. The seeds need a temperature of 80 to 85 degrees F to germinate.

Source:
Llifle Encyclopedia of Succulents – https://www.llifle.com/Encyclopedia/SUCCULENTS/Family/curcubitaceae /34261/Momordica_rostrata