Guaiacum sanctum L., Zygophyllaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Evaluate, score: 3 (Go to the risk assessment)

Other Latin names:  Guaiacum guatemalense Planch. ex Rydb.

Common name(s): [more details]

English: guaiacum, holywood, lignum-vitae, roughbark lignumvitae

Spanish: palo santo

Habit:  shrub/tree

Description:  "Small trees up to ca. 10m tall, leafy branchlets 0.8-3 mm thick, minutely puberulent with thin ascending hairs ca. 0.2 mm long, becoming pale gray and glabrous; stipules 2-4 mm long, triangular and acute, appressed puberulent distally, thick and persisting. Leaves opposite, 3-9 cm long, pinnately compound with (2-) 3-5 (-6) pairs of leaflets, petiole 3-8 mm long, petiole and rachis to 5 cm long, rachis 0.3-0.8 mm thick, minutely puberulent or glabrescent, deeply sulcate above; leaf blades (leaflets) 12-28 (-32) mm long, 4-14 (-16) mm broad, asymmetric and narrowly oblong to oblong-obovate, the middle leaflets the longest on each leaf, bluntly obtuse to acute at the apex, subsessile and unequal on the thick petiolule, with the proximal side usually rounded at the base and the distal side more straight, leaflets drying stiffly chartaceous, glabrous above and below or sparsely sericeous near the base, venation palmate with 1-3 major veins and more weakly defined lateral veins, all these veins strongly ascending and loop-connected distally. Inflorescences fascicles of (l-) 4-8 flowers at distal nodes, peduncles (= pedicels) 12-20 mm long, slender (0.3-0.5 mm thick when dry), sparsely and minutely puberulent. Flowers ca. 15 mm long and 20 mm broad, sepals 4-6 mm long and ca. 3 mm broad, broadly imbricate in bud; petals 8-12 mm long and 6-8 mm broad, broadly obovate and clawed at the base, bright blue; stamens ca. 6 mm long, anthers 1.5-2 mm long, becoming curved; pistil ca. 10 mm long, with a short (2 mm) stipe, and slender style 2-3 mm long, ovary obovoid and drying dark. Fruits 14-16 mm long and 12-18 mm broad, obovoid and prominently 2-5-lobed or ridged, the longitudinal lobes 7-9 mm thick and rounded, fleshy or moist at maturity but drying to a yellowish and lustrous hard surface; seeds ellipsoid, ca. 1 cm long, brown to black and with a red aril.  Guaiacum sanctum is recognized by its opposite compound leaves with 2-5 pairs of small subsessile asymmetric leaflets, the bright sky-blue flowers, and the restriction to lowland deciduous forest formations. The leaflets resemble those of some Leguminosae, but the opposite leaves and lobed capsular fruit are quite different."  (Burger, 1991; pp. 36-37).

"A small or sometimes rather large tree or a large shrub, sometimes 10 meters tall, with dense spreading crown and a thick trunk rarely more than 30 cm. in diameter, the bark pale; leaflets 4-12, oblong to obovate, 2-3.5 cm. long, sessile, coriaceous, glabrous or sparsely sericeous, obtuse or rounded at the apex; stipules 3 mm. long, pubescent, caducous; flowers solitary or several together, on pubescent peduncles shorter than the leaves; sepals obovate or oblong-obovate, 5-7 mm. long; petals blue or purple, broadly obovate, 7-12 mm. long, rounded at the apex, glabrous; capsule broadly obovoid, yellow or orange, about 1.5 cm. long; seeds ellipsoid, dark brown or black, 1 cm. long, with a red aril"  (Standley & Steyermark. 1946; pp. 394-395).

Habitat/ecology:  In Guatemala (native), "plentiful on dry rocky hillsides of the lower Motagua Valley, at 250 meters or less, also frequent on the Pacific plains, at or near sea level"  (Standley & Steyermark. 1946; pp. 394-395).  "Trees of the seasonally very dry and deciduous forest formations in northwestern Costa Rica. The species is found from 10-200 m elevation in Costa Rica, and up to 700 m in Nicaragua"  (Burger, 1991; pp. 36-37).

Propagation:  Seed

Native range:  Florida (U.S.), West Indies, southern Mexico, Central America; also cultivated (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Lau, Alex/Frohlich, Danielle (2013) (p. 12) Voucher cited: A. Lau & D. Frohlich 2012032901 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (year unknown) (voucher ID: PTBG 20728) Taxon name on voucher: Guaiacum sanctum L.
State of Hawaii Hawaiian Islands	O‘ahu Island		Bishop Museum (U.S.A. Hawaii. Honolulu.) (1948) (voucher ID: BISH 72348) Taxon name on voucher: Guaiacum sanctum L.

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Central America Central America (Pacific rim)	Costa Rica (Republic of)	native	Burger, W. C. (1991) (pp. 36-37)
Central America Central America (Pacific rim)	El Salvador (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Guatemala (Republic of)	native	Standley, Paul C./Steyermark, Julian A. (1946) (pp. 394-395)
Central America Central America (Pacific rim)	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) Campeche, Chiapas, Quintana Roo, Yucatan

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	USA (Florida)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Control:  If you know of control methods for Guaiacum sanctum, please let us know.