Scientific Name
Euphorbia guillauminiana Boiteau
Scientific Classification
Family: Euphorbiaceae
Subfamily: Euphorbioideae
Tribe: Euphorbieae
Subtribe: Euphorbiinae
Genus: Euphorbia
Etymology
The specific epithet "guillauminiana" (pronounced gwil-lou-min-ee-AY-nuh) honors André Guillaumin (1885-1974), a French botanist.
Origin
Euphorbia guillauminiana is endemic to Madagascar. It occurs on basaltic rocks in the Analalava District.
Description
Euphorbia guillauminiana is a densely branched succulent shrub with thick, fleshy branches with spines arranged in 8 rows. It can grow up to 3.3 feet (1 m) tall. The leaves are smooth, glossy, dark green, and arranged in rosettes at the tips of the branches. They can measure up to 0.8 inches (2 cm) in length and 0.4 inches (1 cm) in width.
The flowers are yellowish-green or yellow, rarely red, and appear in cymes at branch tips.

Hardiness
USDA hardiness zones 10a to 11b: from 30 °F (−1.1 °C) to 50 °F (+10 °C).
How to Grow and Care
Euphorbias are very easy to care for. These plants require a little pampering to become established, but once they are, they are self-sufficient. More die from overcare and watering than from neglect. Euphorbias need well-draining soil and lots of sunlight. They are not particular about soil pH but cannot tolerate wet soil. Unlike most succulents, Euphorbia does not handle long periods of drought well. It may need watering once a week during the summer. Water whenever the top few inches of soil are dry. Water them deeply, but avoid letting them sit in wet soil, as this can cause root rot. Add some organic matter or fertilizer to the planting hole. Feed with a half-strength fertilizer monthly if you are growing them in containers or your soil is poor.
These succulents can be grown from seed, but they can be challenging to germinate, and they may be difficult to find. They are usually propagated by cuttings. This can be tricky because of the sap that exudes. Rooting hormone is recommended with Euphorbias. They tend to grow problem-free, but there are a few pests and diseases to be alert for.
See more at How to Grow and Care for Euphorbia.
Links
- Back to genus Euphorbia
- Succupedia: Browse succulents by Scientific Name, Common Name, Genus, Family, USDA Hardiness Zone, Origin, or cacti by Genus
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