Edward F. Gilman, Dennis G. Watson, Ryan W. Klein, Andrew K. Koeser, Deborah R. Hilbert, and Drew C. McLean
Introduction
Lignum vitae is an extremely slow-growing broadleaf evergreen which ultimately reaches 30 feet in height and casts light shade, but few people have seen plants of this size because it is not grown in the trade. Most are seen 8 to 12 feet tall with a beautiful array of multiple trunks and a rounded canopy much like that of a mature crape-myrtle. The one to two-inch-long, leathery, dark green leaves are joined at many times throughout the year by the production of large clusters of bluish purple flowers, the old flowers fading to a light silvery-blue and creating a shimmering haze over the rounded canopy. These flowers are followed by small, heart-shaped, yellow orange berries, appearing on the tree at the same time as the bluish purple flowers and creating a lovely sight.
Figure 1. Full Form—Guaiacum sanctum: Lignum vitae
General Information
Scientific name: Guaiacum sanctum
Pronunciation: GWY-uh-kum SANK-tum
Common name(s): Lignum vitae, holywood, tree of life
Family: Zygophyllaceae
USDA hardiness zones: 10B through 11 (Figure 2)
Origin: native to Florida, the West Indies, Mexico, and Central America
UF/IFAS Invasive Assessment Status: native
Uses: tree lawn 3–4 feet wide; tree lawn 4–6 feet wide; tree lawn > 6 ft wide; sidewalk cutout (tree pit); parking lot island < 100 sq ft; parking lot island 100–200 sq ft; parking lot island > 200 sq ft; container or planter; specimen; deck or patio; Bonsai; highway median
Figure 2. Range
Description
Height: 10 to 30 feet
Spread: 8 to 12 feet
Crown uniformity: symmetrical
Crown shape: round, vase
Crown density: dense
Growth rate: slow
Texture: fine
Foliage
Leaf arrangement: opposite/subopposite
Leaf type: even-pinnately compound; made up of 3-5 pairs of leaflets
Leaf margin: entire
Leaf shape: obovate, elliptic (oval)
Leaf venation: pinnate
Leaf type and persistence: evergreen
Leaf blade length: 1 to 2 inches
Leaf color: dark green
Fall color: no color change
Fall characteristic: not showy
Figure 3.Leaf—Guaiacum sanctum: Lignum vitae Credit: Marc S. Frank, University of Florida Herbarium
Flower
Flower color: bluish purple
Flower characteristics: very showy; emerges in terminal clusters
Flowering: most abundant in spring, but also year-round
Figure 4. Flower—Guaiacum sanctum: Lignum vitae
Fruit
Fruit shape: oval
Fruit length: ½ inch
Fruit covering: fleshy; 5-winged capsule
Fruit color: yellow orange
Fruit characteristics: does not attract wildlife; showy; fruit/leaves not a litter problem
Fruiting: most abundant in summer, but also year-round
Figure 5. Fruit—Guaiacum sanctum: Lignum vitae
Trunk and Branches
Trunk/branches: branches droop; very showy; typically multi-trunked; no thorns
Bark: creamy white to gray, and peels in patches with age
Pruning requirement: needed for strong structure
Breakage: resistant
Current year twig color: gray
Current year twig thickness: thin
Wood specific gravity: 1.09
Figure 6. Bark—Guaiacum sanctum: Lignum vitae Credit: Gitta Hasing
Pest resistance: free of serious pests and diseases
Use and Management
Underneath the smooth, beige/grey bark of Lignum vitae is some of the heaviest of all wood, sinking under its weight instead of floating in water. This dense wood was once popular for use in the manufacture of bowling balls and has also been used for propeller shafts on steamships, gears and for mallets. The picturesque crooked, typically multiple trunk, evergreen leaves, and beautiful flowers, and fruit would all combine to make Lignum vitae a popular choice for use as a container, patio, or specimen planting if it were widely available in a range of sizes. Unfortunately, like many other slow-growing trees, this one is not often grown in nurseries. One must travel to arboreta to view nice specimens of this tree.
Lignum vitae can be grown in full sun or partial shade on a wide variety of soils, including alkaline. Plants will easily tolerate wet or dry soil, wind, and salt, making it an ideal choice especially for seaside plantings.
Guaiacum officinale grows 10 to 30 feet tall, has blue or sometimes white flowers, and light to dark brown seeds.
Propagation is by seed.
Pests and Diseases
No pests or diseases of concern.
Reference
Koeser, A. K., Friedman, M. H., Hasing, G., Finley, H., Schelb, J. 2017. Trees: South Florida and the Keys. Gainesville: University of Florida Institute of Food and Agricultural Sciences.
