202 ZYGOPHYLLACEAE. 



or ellipsoid; embryo nearly straight. [From the aboriginal name.] About 8 

 species, natives of tropical and subtropical America. Type species: Guaiacum 

 offlcinale L. 



Petals tomentulose; fruit broadly obcordate ; leaflets mostly 4. 1. G. offlcinale. 



Petals glabrous ; fruit broadly obovoid ; leaflets mostly 6-10. 2. G. sanctum. 



1. Guaiacum officinale L. Sp. PI. 381. 1753. 



A tree up to 10 m. high, the bark smooth and gray, the branches flexuous. 

 Leaves 3-9 cm. long; leaflets 4 or 6, mostly 4, oval to obovate, glabrous, 1-5 

 cm. long, rounded at the apex, sessile or nearly so, coriaceous at maturity; 

 stipules 1 mm. long, pubescent, caducous; flowers few or many, terminal, the 

 slender peduncles pubescent; sepals ovate to orbicular, 5-7 mm. long, tomentu- 

 lose on both sides; petals blue, narrowly obovate, about 12 mm. long, tomentu- 

 lose at the apex, rounded or mucronate; fruit usually 2-carpellary, broadly 

 obcordate, yellowish, 17-20 mm. long; seeds ellipsoid, the aril cream-colored. 



Coppices and scrub-lands, South Caicos : Cuba to St. Thomas and to Trinidad ; 

 Jamaica ; Panama to northern South America. LIGNUM VITAE. 



2. Guaiacum sanctum L. Sp. PI. 382. 1753. 



A tree, sometimes 10 m. high, the bark pale, the branches spreading or 

 pendulous. Leaves 4-10 cm. long; leaflets 4-10, oblong to obovate or oblanceo- 

 late, 2-3.5 cm. long, sessile, glabrous, coriaceous at maturity, usually apiculate 

 or mucronate; stipules about 3 mm. long, pubescent, usually caducous; flowers 

 solitary or several, on pubescent peduncles shorter than the leaves; sepals 

 obovate or oblong-obovate, 5-7 mm. long, pubescent; petals blue or purple, 

 broadly obovate, 7-11 mm. long, glabrous, rounded at the apex; fruit broadly 

 obovoid, yellow to orange, 14-17 mm. long; seeds ellipsoid, the aril scarlet. 



Coppices and scrub-lands, throughout the islands from Abaco and Great Ba- 

 hama to Watling's, Inagua, Anguilla Isles and North Caicos : Florida ; Cuba 

 to Porto Rico ; Yucatan. LIGNUM VITAE. 



2. THIBULUS L. Sp. PL 386. 1753. 



Herbs, with evenly pinnate leaves and peduncled axillary yellow flowers. 

 Sepals 5, persistent. Petals 5, deciduous. Stamens 10, the alternate ones 

 somewhat longer. Ovary sessile, 5-lobed, 5-celled, hairy, the hairs erect; style 

 short; stigma 5-ridged; ovules 3-10 in each cavity, pendulous. Fruit 5-angled, 

 spiny, splitting into 5, 3-5-seeded segments. [Greek, three-pronged, Caltrop, 

 from the resemblance of the fruit to that implement.] About 12 species, of 

 warm and tropical regions. Type species : Tribulus terrestris L. 



1. Tribulus cistoides L. Sp. PI. 387. 1753. 



Tribulus terrestris cistoides Oliver, Fl. Trop. Afr. 1: 284. 1868. 



Perennial; roots thick, woody; stems diffuse, procumbent, 3-10 dm. long, 

 pubescent, becoming glabrate. Leaves 1-5 cm. long; leaflets 6-8 pairs, 

 obliquely oblong or elliptic, acutish or obtuse and mucronulate, 415 mm. long, 

 silky -pubescent beneath; stipules subulate, 5-8 mm. long; peduncles about as 

 long as the leaves or longer; sepals lanceolate, half as long as the petals; 

 petals yellow, about 2 cm. long; carpels tubercled, each with 2 stout divergent 

 spines and several scattered smaller ones. 



Sandy waste places, Fortune Island, Grand Turk and Inagua : Georgia and 

 Florida ; Cuba to Virgin Gorda ; Guadeloupe and Martinique ; Jamaica ; Panama 

 north to the islands off the California coast. LARGE YELLOW CALTROP. BUTTERCUP. 



