Adenia volkensii
Volkens' bottle tree
Adenia volkensii is an imposing arborescent caudiciform succulent of the family Passifloraceae, endemic to the arid savannas of East Africa — primarily Tanzania, Kenya, and Ethiopia. It develops a massive, bottle-shaped or columnar main trunk with a smooth, pale grey, photosynthetically active bark, reaching 4–7 m in height and 60–100 cm in diameter at the base. Unlike other adenias with trailing stems, A. volkensii forms a defined tree with an open crown and deciduous leaves. It contains extremely toxic lectins such as stenodactylin, one of the most lethal proteins known, which was investigated for potential use in biological warfare agents during the Cold War.
chevron_right edit_note Proposed edits auto-approved at +3 net votes
No pending proposals for this section.
Overview
| Category | Classification |
|---|---|
| Family | Passifloraceae |
| Genus | Adenia |
| Growth Habit | Arborescent caudiciform tree of columnar to bottle-shaped habit, slow-growing, with an open crown and seasonal deciduous leaves |
| Conservation Status | Vulnerable in parts of its range due to habitat loss and illegal collection for the plant trade. Listed on CITES Appendix II as a regulated caudiciform Passifloraceae species. |
| pH Target | 6.0–7.5 |
| Type | Arid mineral with gravel and coarse sand, very high porosity. In nature it grows in volcanic rock and weathered granite soils. |
Origin & Habitat
Morphology
Massive, bottle-shaped or columnar, with a very swollen base that tapers gradually towards the crown. Smooth, pale grey to greenish-white bark with photosynthetic capacity. Basal diameter 60–100 cm, height 4–7 m in mature wild specimens. Stores large quantities of water and energy reserves.
ecoSimple, alternate, ovate to orbicular, 4–10 cm long, slightly lobed into 3 rounded lobes, medium green to grey-green. Deciduous: they appear with seasonal rains and fall during the dry season.
ecoSmall, tubular, yellow-green to creamy white, 1.5–2.5 cm, gathered in axillary cymes. Dioecious species. Male flowers have 5 exserted stamens; female flowers have a superior ovary with 3 stigmas. Flowering at the onset of the wet season.
ecoDeep and lateral root system, with thickened roots in the transition zone to the trunk. In stony soils the roots adapt to cracks and fissures. In container cultivation, root growth can deform soft plastic containers.
ecochevron_right edit_note Proposed edits auto-approved at +3 net votes
No pending proposals for this section.
Requirements
Soil & Substrate
Type
Arid mineral with gravel and coarse sand, very high porosity. In nature it grows in volcanic rock and weathered granite soils.
groups Beneficial Associations
chevron_right edit_note Proposed edits auto-approved at +3 net votes
No pending proposals for this section.
Propagation Strategy
- 1 Manually scarify the seed coat with fine sandpaper or abrasive paper, or soak in hot water (40 °C) for 24 hours.
- 2 Sow in sterilised mineral substrate (sand + perlite) at 1 cm depth.
- 3 Maintain at 30–35 °C with moderate humidity and bright indirect light.
- 4 Germination is hypogeal: the radicle emerges first and thickens to form the primary caudex.
- 5 Keep seedlings in semi-shade during the first month before acclimatizing to full sun.
- 6 The first transplant to an individual pot must be done with extreme care to avoid damaging the storage roots.
- 7 First signs of the bottle-shaped trunk are visible around year 2–3 of cultivation.
In temperate climates, grow in a warm greenhouse or bright interior during winter; this species does not tolerate outdoor low night temperatures.
Watering during dormancy: causes trunk rot within weeks, frequently fatal.
Every 4–5 years, only in late spring. Prefer a pot slightly larger than the trunk, with excellent drainage.
Monthly fertilisation during spring and summer with low-nitrogen mineral fertiliser (NPK 3-8-8 or similar). Do not fertilise in autumn or winter.
Uses & Applications
Precautions / Toxicity
EXTREMELY TOXIC. Adenia volkensii contains stenodactylin, a type A-B lectin (Type II Ribosome-Inactivating Protein) with toxicity comparable to ricin. Classified as one of the most lethal proteins known. Ingestion of any part of the plant can be fatal. The sap can cause severe irritation to mucous membranes and skin. It was the subject of research in biological weapons programmes during the Cold War. Handle exclusively with gloves, mask, and protective eyewear. Keep absolutely away from children, pets, and water sources.
chevron_right edit_note Proposed edits auto-approved at +3 net votes
No pending proposals for this section.
Plant Health
Basal trunk rot (Fusarium spp. / Phytophthora spp.): the greatest risk in cultivation. Manifests as softening and brown discolouration at the base of the trunk. Treatment: remove all affected tissue, allow the cut to dry for 7–10 days, apply copper-based fungicide paste, and repot in completely dry substrate.
Soft scale (Coccus hesperidum): forms colonies under leaf axils and on young branches, secreting honeydew that promotes sooty mould. Treatment: mechanically scrape off scales, apply 1–2% mineral paraffin oil or systemic insecticide.
Sunburn in young seedlings: an abrupt change in light conditions can burn the trunk epidermis. Acclimatize gradually over 2–3 weeks to full sun, starting with 2–3 hours of direct sun and progressively increasing.
chevron_right edit_note Proposed edits auto-approved at +3 net votes
No pending proposals for this section.
"Stenodactylin from A. volkensii was first purified by De Virgilio et al. (2010) and confirmed as a Type II RIP of exceptional potency. Unlike ricin (Ricinus communis), its B chain has a different lectin specificity, making it the subject of oncological research for targeted immunotoxin therapies. In African botanical gardens, mature specimens of A. volkensii are used as natural indicators of well-preserved dry savanna ecosystems."
chevron_right edit_note Proposed edits auto-approved at +3 net votes
No pending proposals for this section.
Scientific Integrity
🟡 MediumVote to help validate this record
Sources
Loading…
Discussion
Disclaimer
This species record is provided for educational and informational purposes only. Jardín Roca Negra does not guarantee the accuracy or completeness of the data. Content is community-curated and may be subject to revision; it should not replace advice from a qualified botanist. This species may be toxic, invasive, or subject to legal restrictions — verify before handling or cultivating. Jardín Roca Negra accepts no liability for any harm arising from reliance on this information. Images are reproduced under Creative Commons or equivalent free licenses; credits are noted below each image.