Euphorbia bulbispina

Euphorbia bulbispina is a small shrub from northern Madagascar. Some of its parts are succulent. It belongs to Euphorbiaceae, the spurge family. Its home range includes the district of Antsiranana. Known sites lie around Windsor Castle, also called Bobaomby. It grows on that summit and on rocks nearby. It may also grow farther south at Montagne des Francais. That site is not yet certain. Kew places it in the tropics, where dry spells come with the seasons.

This low shrub grows about 1 foot [0.3 metres] tall, sometimes more. Its many branches spread about 3.3 feet [1 metre] or farther. Young plants have a clear main stem. Its base is swollen, with spines where branches join. Many side shoots grow from this main stem. The lower branches die as the plant grows. The upper branches form a crown above the main stem. They branch at their tips, or close to them. A thick coat of dark brown wax covers them. Each branch grows more narrow toward its base.

The leaves fall off; they do not stay year-round. They grow at shoot tips, often in groups of five. Each leaf is egg-shaped, with a dull green surface. The leaves have red edges and short, purple stalks. The single stipular spines have broad, swollen bases. These bases give the species its name. The spines start out purple and turn grey-brown with age. The swollen stem and branched crown give the shrub its compact form.

Small flower clusters grow just below the shoot tips. Each simple cyme, a flower cluster, holds two cyathia. These small, cup-like flower structures measure about three millimetres across. Egg-shaped cyathophylls spread out around them. These parts are cream-yellow or white. Their nectar glands range from green to yellow-green. The pale parts stand out against dark stems and green leaves. The account notes that short stalks hold the ovaries.

In the wild, this shrub roots in limestone cliff cracks. It also grows among rocks on mountain peaks. Its known range seems small, but its full extent is unclear. LLIFLE places the known sites outside areas set aside for protection. Harm to its habitat and fire threaten the shrub. So does taking plants for the plant trade. It is hard to grow in two ways. Moving a plant is hard, and cuttings do not root well. These limits matter when moving a grown plant or trying to make more.