Species · genus Euphorbia · Euphorbiaceae

Thornless Crown Of Thorns

Euphorbia geroldii Rauh

Growth habit

semisucculent shrub

Native range

Madagascar

Euphorbia geroldii — reference photo — no rights reserved · CC0

Cultivars of E. geroldii

The named forms growers keep — each with its own page, each honest about how much we know.

No named cultivars catalogued under E. geroldii yet. When growers document a stable, named form, it earns its own page here.

Guide

The species-level account. Cultivar pages build on this and say where they differ.

A Madagascan Euphorbia

Euphorbia geroldii is a species in the Euphorbiaceae family, the same broad group as poinsettias and spurges, which typically bear milky sap and small flowers cupped in often colourful bracts. It was first described by Rauh and published in 1994, and is currently accepted as a distinct species.

Source: RHS

Native to Madagascar

This plant's native range is confined to northeastern Madagascar, around Vohémar. It grows as a semi-succulent shrub, and its natural home is the seasonally dry tropical biome, a habitat that alternates between wet and dry spells through the year.

Source: Kew

A semi-succulent shrub

Euphorbia geroldii takes the form of a semi-succulent shrub, a habit suited to its seasonally dry native ground. Like others in its genus, it carries the milky sap and cupped, often coloured bracts typical of Euphorbia.

Source: RHS

Care recipe

The species record — the baseline every cultivar inherits unless it says otherwise.

Care notes are early — not yet verified

Light: ai:claude-opus-4-8
Water: ai:claude-opus-4-8 (range 10-21d)
Humidity: ai:claude-opus-4-8
Soil: ai:claude-fable-5
Care: ai:claude-fable-5

Light

Direct sun

Water

≈ every 21 days

Humidity

Low — average room

Temperature

15–30 °C

Soil mix

Gritty, fast-draining succulent mix

Propagation

Stem cuttings, callused before rooting

Fertilizing

Dilute balanced feed monthly in the growing season

Growth rate

Moderate

Flowering

Repeat-blooming red bracts in good light, thornless stems

ToxicityAuthoritative · species

Toxic to cats & dogs & humans

Euphorbiaceae exude an irritant milky latex that can harm skin, eyes, and mucous membranes if ingested or handled. This is where toxicity lives: every cultivar of this species inherits it and none can override it.

Reference images

Every image credited. Licenses link to their deeds.

Sources: ai:claude-opus-4-8 · ai:claude-opus-4-8 (range 10-21d) · ai:claude-fable-5 · ai:claude-opus-4-8 (family inference)

Kept true by its growers

Every fact here carries its source. Grow Thornless Crown Of Thorns yourself? What you’ve observed — how it drinks, how it holds its color, a name that’s off — and a clear photo of your plant are exactly what keep this page honest. Contributions are reviewed before anything changes.