Adenia (2018)

By Bob Williams (February 2018)

Sometimes botanists like to play cruel jokes on people. Mention the genus Adenia to most people, and more often than not, you will be corrected that the name is Adenium.

Both genera can grow impressive caudices. They lose their leaves in the winter. They can grow fast. That is where the similarities end.

Adeniums are known for their flowers. The flowers of Adenia are small and non-descript, but plants in the genus have things going for them that make them attractive to the caudex-loving individuals among us. They seem to be hardy. They grow fast. They can form a large caudex.

Adenia is a genus of flowering plants in the passion flower family, Passifloraceae. The genus name Adenia comes from “aden,” described as the Arabic name for the plant by Peter Forsskål, the author of the genus.

All adenias are perennial plants, but there are many different forms, including herbs, vines, shrubs and trees. Many are succulents, and some are pachycauls with thick stems and few or no branches. Some have fibrous root systems, and some have tubers.

Adenia plants can be found in a wide variety of habitats, from the dry African deserts to wet Southeast Asian rainforests. There are some 100 species in the genus.

Adenias are strange plants. They have medicinal uses, yet many species are toxic. Several species are used in traditional African medicine. Various parts of A. cissampeloides are used to treat conditions that include gastrointestinal problems, inflammation, pain, fever, malaria, leprosy, cholera, anemia, bronchitis, sexually transmitted diseases, and mental illness.

A. dinklagei leaves are ingested to treat palpitations. The leaves of A. tricostata are used to treat fever. The leaves or leaf sap of A. bequaertii are taken to treat headache and mental illness. A. lobata stems are applied to sites of Guinea worm infection and are used as an enema and an aphrodisiac. A. cissampeloides is used as a fish poison and arrow poison. The fruit of A. digitata has been used in Africa to commit homicide and suicide.

The toxicity can come from sap like a euphorbia or from ingesting leaves or fruits. Handle this plant group with care.

The Adenia plants that those in the hobby covet mainly grow in southern Africa and Madagascar. In habitat, they are often found in brush, with the branches scrambling up through the bushes. When growing in open areas, the plants form their own “bush,” with new growth from the base coming through mostly dead stems.

This creates something of a dilemma for growing these plants. They are shrubs or small trees that grow in a hot, full-sun environment, yet their caudices are almost entirely shaded. Full sun will “sunburn” the base.

Adenia plants should be grown in bright, indirect light or under shade cloth. Like most succulents, they like fast-draining soil and frequent watering during the summer. I read that they can take watering every four to five days. Only water when the soil has dried, though. Do not keep the soil constantly moist.

When the weather turns cool, these plants lose their leaves. Quit watering. They can get by in the winter with no water. Cold, soggy soil is a death sentence for these plants. They are not cold-hardy for this area and should be sheltered or brought in before temperatures drop to 45 degrees F or below.

Once the leaves fall, you can prune the vines back from 6 to 12 inches. Adenias flower in the spring, but apparently the flowers are nothing to write home about.

Propagation can be by either stem cuttings or seed. When doing stem cuttings, the odds of a caudex forming are low. If trying to propagate by seed and you want to do your own pollination, adenias have male and female plants, so you need one of each. In reading about care for this plant, I found they like a soil ph between 6.1 and 6.5.

As I said, these plants can grow fast. Most can form a caudex 6 feet in diameter and up to 2 feet tall. Some information suggests that repotting every two or three years may be required because of this rapid growth.

Some of the more commonly grown Adenia species are A. glauca, A. aculeate, A. globose, A. digitata, A. pechuelii and A. spinosa. They can be found fairly easily for sale.

Overall, there is not a large amount of information available on these plants. I am not sure why. Maybe it got posted under Adenium.