Adenium 'Khao' Dorset Horn

Geographic & Climate

Geographic Coordinates: Cultivar / Horticultural selection (Origin: Cultivated origin, selected from Thailand / Southeast Asian nurseries; wild type Adenium obesum native to East Africa to the Arabian Peninsula, ca. $10^{\circ}\text{N}$ to $15^{\circ}\text{S}$, $35^{\circ}\text{E}$ to $50^{\circ}\text{E}$)

Climate Classification: Horticultural Cultivar (Derived from Tropical and Subtropical Arid / Semi-arid climates, Köppen Aw / BSh)

Habitat Characteristics: Cultivated garden/nursery environment; original wild species thrive at altitudes of 0–1,500 meters in well-drained sandy-loam soils, rock crevices, and seasonal rainfall regimes with prolonged dry periods.

Botanical Morphology

Diagnostic Features: Adenium 'Khao' is a distinct horticultural selection characterized by its pristine, luminous pure white flowers, often featuring a subtle yellowish or greenish throat. Unlike the standard pink or deep red species forms, the petals maintain a clean, solid white coloration without heavy margin striping. It develops a swollen, sculptural caudex (pachycaule trunk) with smooth, grey-green bark and dense branching.

Growth Habit: Summer-growing deciduous to semi-evergreen shrub with a moderate growth rate. Reaches a mature height of 60–120 cm in container cultivation. Enters dormancy during cooler, shorter days with reduced watering.

History & Etymology

Etymology: The genus name Adenium derives from "Aden", the historical port city in Yemen near where specimens were first collected. The cultivar epithet 'Khao' (derived from Thai) translates to white, directly referencing the pure white coloration of the flowers.

Historical Context: Developed through selective breeding programs by Southeast Asian nurserymen (predominantly in Thailand, a global hub for Adenium hybridisation) to isolate and stabilize pure white floral phenotypes combined with compact, caudiciform growth habits.