CALTROP FAMILY (ZYGOPHYLLACEAE) 



Key to the 2 native species, both illustrated (Nos. 93-94) 



A. Leaflets mostly 4, sometimes 6; fruits mostly flattened, heart-shaiied at apex — 93. Oiiaiacum officinale. 

 AA. Leaflets mostly 6-10; fruits deeply 5- or 4-angled or winged, pointed at apex — 94. Guaiacum sanctum. 



93. Guayacan, common lignumvitae 



A handsome small evei-f^-een tree with a dense 

 rounded crown and dark jjreen foliai^e, easily rec- 

 ognized by: (1) light brown bark smoothish and 

 mottled, peeling off in thin scales; (2) opposite 

 even pinnate leaves with mostly 4 or 6 stalkless, 

 oblique, broadly elliptic or obovate leathery leaf- 

 lets; (3) several to many deep to pale blue flowers 

 with 5 petals minutely hairy on the outer surface, 

 spreading starlike %-% inch across in showy ter- 

 minal ancl lateral clusters shorter than the leaves; 

 and (4) flattened orange-brown cai^sules % inch 

 long and broad, heart-shaj^ed and slightly winged, 

 attached at narrowed end. 



A tree 15-30 feet high, with a short trunk 4-18 

 inches in diameter. The bark scales are 1-2 inches 

 across and u])on falling expose smoothish gray- 

 brown spots beneath. Inner bark is light brown 

 and bitter. Tlie green twigs, turning to gray, have 

 enlarged ringed nodes and are nuich branched and 

 widely forking. 



Leaves are 1V2~3 inches long, with green axis 

 and at base paired minute hairy scales (stipules) 

 which shed early. Leaflets are %-2 inches long 

 and %-lVi inches wide, roundecl or sometimes 

 blunt-pointed at both base and apex, broadest on 

 the side toward base of leaf, slightly thickened and 

 often turned under at edges, hairless, and dark 

 green or olive green on both sides, slightly shiny- 

 above. The lowest pair of leaflets is at the base of 

 axis beside the twig, while the pair of leaflets at 

 apex is largest. 



Many pretty, faintly fragrant flowers are 

 clustered together (nmbellike) on slender minute- 

 ly hairy stalks %-l inch long. There are 5 broad 

 rounded finely hairy sepals nearly 14 irich long; 

 5 spreading deep to pale blue petals nearly Yj inch 

 long, narrowed at base and rounded at apex, mi- 

 nutely hairy on outer surface; 10 stamens about 

 %6 inch long, with blue filaments and yellow 

 anthers; and stalked pistil I/4 inch long, with flat- 

 tened usually 2-celled ovary and pointed style. 



The flattened capsules minutely pointed at the 

 heart-shaped apex are green when immature, turn- 

 ing orange brown. They split open to discharge 

 2 or 1 seed 1/2 inch long, brown with a red fleshy 

 covering (aril). Flowering and fruiting from 

 early spring to fall. 



The narrow sapwood is pale yellow. Heartwood 

 is dark greenish brown or nearly black. Lignum- 

 vitae is one of the heaviest commercial woods (spe- 

 cific gravity about 1.2-1.3). It is extremely hard, 

 of very fine uniform texture, with highly inter- 

 locked grain, growth rings clearly defined, and 

 characteristic oily feel caused by the unique resin 

 content. The wood is difficult to season and work 

 but takes a fine polish. The heartwood is very 



212 



Guaiacum officinale L. 



durable and very resistant to decay. It is very 

 resistant to attack by dry-wood termites, but the 

 sapwood is susceptible. 



The self-lubricating resinous wood is so valuable 

 that it is sold by weight, though not now of com- 

 mercial importance in Puerto Rico. It is famed 

 for its special use in bearings and bushing blocks 

 for propeller shafts of steamships. It serves also 

 for pulley sheaves, deadeyes, and as a replacement 

 for metal bearings in roller mills. Other uses in- 

 clude handsaw guides, awning rollers, furniture 

 casters, mallets, bowling balls, and turned nov- 

 elties. 



Under the name lignumvitae (Latin for wood 

 of life), the extract of this wood formerly was 

 official in medicine as a stimulant and to increase 

 perspiration. Earlier it was thought to be a cure 

 for various diseases, having been introduced in 

 Europe about 1508. Also employed medicinally 

 was guaiac resin, which exudes from bark and sap- 

 wood, reddish brown in color but changing to blue 

 or blue green. 



The trees occasionally are planted as orna- 

 mentals for the masses of blue flowers, which are 

 rare in the tropics, and for the handsome dark 

 green foliage. However, their growth is slow, so 

 slow that forest plantings in Puerto Rico by the 

 Forest Service have been discontinued in favor of 

 other species. Bees visit the flowers. 



Forests, thickets, and pastures in the dry coastal 

 and dry limestone regions of Puerto Rico from 

 Guayama to Cabo Rojo. Also in Culebra, Vieques, 

 St. Croix, St. Thomas, and St. John. Reported to 

 be nearly exterminated on Virgin Islands except 

 in cultivation. 



Public forest. — Guanica. 



MuNflCIPALITIES WHERE ESPECIALLY COMMON. 



12, 66. 



Ranoe. — West Indies from Bahamas and Great- 

 er Antilles to Martinque in Tjcsser Antilles and in 

 Bonaire, Curasao, and Aruba. Also in Panama, 

 Colombia, Venezuela, and British Guiana. Plant- 

 ed in southern Florida, Bermuda, Trinidad and 

 Tobago, Surinam, and elsewhere in tropical 

 America. 



Other common names. — guayaco (Puerto 

 Rico) ; lignumvitae (Virgin Islands) ; guayacan 

 (Spanish) ; palo santo (Cuba, Venezuela) ; guaya- 

 can negro (Cuba) ; guayacan de playa, guayacan 

 colombiano, guayaco (Colombia) ; lignumvitae, 

 common lignumvitae (United States, English, 

 commerce) ; gaiac (French, commerce) ; gai'ac 

 franc, ga'ic male (Haiti) ; bois saint (Martinique) ; 

 wayaca, pokhout (Dutch West Indies) ; guaiaco, 

 pan santo (Brazil). 



The generic name is also spelled Guajacum. 



