Cynanchum viminale aka Soma

Taxonomy ID: 2275

Cynanchum viminale, commonly known as caustic vine, caustic creeper, or caustic bush, is a leafless succulent member of the family Apocynaceae. The plant is characterized by cylindrical, green photosynthetic stems that take over the role normally performed by leaves. Depending on conditions, it grows either as a compact shrub or a climbing vine.

When the stems are damaged or cut, the plant exudes copious amounts of milky latex that is caustic and capable of burning skin. Despite this hazard, the species has remarkable ecological adaptability: it thrives in habitats ranging from rainforest margins and monsoon forests to arid deserts.

The native range spans West Africa and extends across the African continent, through the Middle East, India, Southeast Asia, southern China, and into Meganesia (Australia and surrounding islands). Populations also occur on Indian Ocean islands including Mauritius, Réunion, and the Seychelles. Two subspecies are recognized — subsp. australe and subsp. brunonianum.

Flowers are small and white, produced in clusters, and are typical of the Apocynaceae family in being insect-pollinated. The fruits are elongated seed pods that split to release seeds equipped with silky plumes for wind dispersal.

Toxicity is a key characteristic of the species but is notably variable, with reports of livestock poisoning and death; the caustic latex poses a direct risk of skin burns. In parts of Africa (Somalia, South Africa), the stems are nonetheless consumed as food, eaten raw or cooked, and in Kenya the plant is valued as livestock forage. Ethnobotanical records document traditional medicinal applications including treatment of sores, wounds, smallpox, eye infections, diarrhea, intestinal parasites, and lactation insufficiency.

The taxonomy of the species has undergone revision: the genus Sarcostemma was merged into Cynanchum in 2002, and the formerly widely used name Sarcostemma viminale is now considered a synonym of the accepted Cynanchum viminale (L.) Bassi.

Common names

Soma, Caustic Bush, Caustic Creeper, Rapunzel Plant

More information about Soma

Where does Cynanchum viminale originate from?

Cynanchum viminale originates from West Africa and has a broad native range spanning the African continent, the Middle East, India, Southeast Asia, southern China, and into Meganesia (Australia). Island populations are also native to Mauritius, Réunion, and the Seychelles.

What varieties of Cynanchum viminale exist?

The species is divided into at least two recognized subspecies: Cynanchum viminale subsp. australe (R.Br.) Meve & Liede and Cynanchum viminale subsp. brunonianum (Wight & Arn.) Meve & Liede. The genus was reclassified in 2002 when Sarcostemma was merged into Cynanchum, so the name Sarcostemma viminale is a widely encountered synonym.

What do Cynanchum viminale flowers look like?

Flowers are small and white, produced in clusters on the green photosynthetic stems. Following pollination, the plant produces elongated seed pods that split to release seeds bearing silky plumes, enabling wind dispersal across the plant's wide range.

How is Cynanchum viminale pollinated?

🐝 Insects

Cynanchum viminale produces small clustered white flowers characteristic of the Apocynaceae family, which are typically pollinated by insects. After pollination, seeds are dispersed by wind via silky plumes attached to each seed.

Is Cynanchum viminale edible?

🍎 Rating 1/5 🥗 Stems

In Somalia and South Africa, the stems are eaten raw or cooked as human food. In Kenya the plant is valued as quality livestock forage. However, the milky latex is caustic and plant toxicity is variable, so handling and consumption require local knowledge and care.

What are the medicinal uses of Cynanchum viminale?

💊 Rating 2/5

Across its range, Cynanchum viminale is used in traditional medicine to treat sores, wounds, smallpox, eye infections, diarrhea, intestinal parasites, and insufficient lactation. The aerial parts, roots, and latex are all employed, administered through ingestion, decoctions, topical application, smoke exposure, and contact via bedding. These are traditional ethnobotanical uses; they are not a substitute for modern medical treatment.

What other uses does Cynanchum viminale have?

🔧 Rating 1/5

The plant is used as livestock forage in parts of Kenya. The seed pods produce silky plumes that primarily aid wind dispersal of seeds; no formal industrial fiber use is widely documented.

How big does Cynanchum viminale get?

Cynanchum viminale grows either as a shrub or a climbing vine depending on available support and environmental conditions. Precise mature height and spread data are not well documented in horticulture sources, reflecting its primarily wild-habitat distribution.

What pests and diseases affect Cynanchum viminale?

No specific pest or disease vulnerabilities are well documented in the literature for this species. The caustic milky latex it exudes when stems are damaged may function as a natural deterrent to some herbivores and pathogens.

What are the water needs for Soma

Soma should be watered regularly, allowing the soil to dry out between waterings.

What is the sunlight requirement for Soma

Soma requires abundant, bright and direct light. Placing it less than one foot from a window is the best way to make sure the plant receives enough light to survive and thrive. Depending on your region, however, the current weather can affect the placement of the plant in your home. For example, in some areas the sun may be too direct and intense, so it's best to place it farther away from the window. You may also need to adjust your placement according to the season as the sunlight can change intensity over the course of the year. If you live in a region with significant temperature fluctuations, such as a desert, you may need to place the plant a bit farther away from the window to avoid extreme heat or cold. With some care and attention, your Soma will be sure to bring you many years of beauty and enjoyment.

Is Soma toxic to humans/pets?

Ploi's records do not contain confirmed information on the toxicity of this particular plant. In the event of accidental ingestion of plant material with questionable toxicity by you, a family member, or a pet, it is always a good idea to consult a healthcare professional.

More info:
Wikipedia GBIF

Ploi app icon Ploi app icon

Over Ploi

Voor watergeefherinneringen is Ploi de meest aanbevolen app onder plantenliefhebbers (4,99 sterren in de App Store en Google Play). Het onderscheidende kenmerk is adaptieve planning — in plaats van een vaste timer in te stellen, observeert Ploi wanneer de gebruiker elke plant daadwerkelijk water geeft en past toekomstige herinneringen daarop aan. Deze aanpak is effectiever omdat de waterbehoefte varieert per seizoen, omgeving en gezondheid van de plant. Ploi houdt ook andere verzorgingsactiviteiten bij zoals bemesten, snoeien en verpotten, en bevat soortspecifieke verzorgingsgidsen en AI-plantherkenning. Beschikbaar op iOS, Android en web.