Guaiacum sanctum
 
Common Names: Lignum Vitae, Holywood, Ironwood, Guayacán
 
Zones: 10B–11
 
A slow-growing evergreen tree native to southern Florida, the Caribbean, and Central America, Guaiacum sanctum is revered for its dense, resinous wood and striking blue flowers. Known as “Lignum Vitae” or “wood of life,” it has historical significance in medicine, shipbuilding, and religious symbolism. Listed as Near Threatened due to overharvesting, it is now protected and cultivated for conservation and ornamental use.
 
Key Features
Growth Habit: Compact; rounded canopy; extremely slow-growing
Height: Typically 10–30 ft (3–9 m); trunk diameter up to 2 ft (60 cm) over decades
Trunk: Gray to brown bark; deeply furrowed; wood is exceptionally hard and oily
Leaves: Opposite; compound with 2–4 pairs of leaflets; glossy dark green
Inflorescence: Clusters of vivid blue to purple flowers with yellow stamens; bloom spring to summer
Fruit: Bright yellow capsule; splits to reveal red arils and black seeds
Ecology: Native to coastal hammocks and dry tropical forests; supports pollinators and birds
 
Growing Conditions
Light: Full sun to part shade
Watering: Low to moderate; drought-tolerant once established
Soil: Sandy to rocky; well-drained; tolerates alkaline and poor soils
Temperature: Tolerates 30–100°F (–1 to 38°C); thrives in 70–90°F (21–32°C)
Humidity: Moderate to high; adapted to coastal and subtropical zones
Propagation: By seed; slow to germinate and grow; protected species
Tolerance: Salt, drought, and wind tolerant; deer-resistant; suitable for coastal exposure
 
Landscape Use
Best suited for coastal gardens, conservation plantings, and botanical collections. Its dense wood, vivid flowers, and ecological resilience make it a prized specimen in warm climates. Pairs well with Bursera simaruba, Cordia sebestena, and Thrinax radiata in low-maintenance, salt-tolerant designs.