Aloe castilloniae J.-B.Castillon
Castillon's limestone aloe
Aloe castilloniae is a recently described species from southwestern Madagascar, where it inhabits the singular spiny forest on calcareous substrates of the Toliara region. Described by J.-B. Castillon, it belongs to the group of Malagasy aloes adapted to extreme heat, drought and poor calcareous soils. Its rarity in botanical collections makes it a sought-after species for specialists.
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Overview
| Category | Classification |
|---|---|
| Family | Asphodelaceae |
| Genus | Aloe |
| Growth Habit | Medium rosette on short stem, solitary |
| Conservation Status | Vulnerable |
| pH Target | 7.5–8.5 |
| Type | Calcareous lithosol, extremely porous and poor |
Origin & Habitat
Morphology
Leaves 25–40 cm long, grey-green to glaucous, with white to brown spiny marginal teeth and pronounced terminal spines.
ecoShort stem 15–30 cm, covered by adhered dry leaf remnants.
ecoTubular flowers 3–3.5 cm long, orange to orange-red, in simple or few-branched racemes on 50–70 cm peduncles.
ecoDeep roots penetrating calcareous crevices to seek water and nutrients in lithosolic soils.
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Requirements
Soil & Substrate
Type
Calcareous lithosol, extremely porous and poor
groups Beneficial Associations
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Propagation Strategy
- 1 Sow in highly porous calcareous substrate at 24–28 °C.
- 2 Keep slightly moist with spray and cover with film.
- 3 Germination in 3–6 weeks; gradually remove film.
- 4 Seedlings are delicate; transplant at 4–5 cm with great care.
- 1 Separate offsets with a clean knife during the warm season.
- 2 Allow to callus for 3 days in a very dry environment.
- 3 Plant in calcareous substrate with very little initial watering.
- 4 Root in 5–8 weeks.
Replicate the semi-arid climate of the Malagasy southwest: intense heat and prolonged drought.
Frequent watering, fatal for this ultra-xerophytic species.
Every 4–5 years; handle with gloves due to spines
No regular fertilisation; optionally one minimal dose of alkaline mineral fertilizer in spring
Uses & Applications
Precautions / Toxicity
Toxic if ingested; spines cause physical injury.
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"Formally described in the early 21st century, A. castilloniae underscores how many Malagasy aloe species remain undescribed in the most inaccessible areas of the spiny forest; current molecular studies suggest at least 10–15 species pending formalisation in that biome."
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Scientific Integrity
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Sources
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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.