16 ZYGOPHYLLACEAE 



spicuous disk. Ovary 5-celled, with 2 ovules in each cell ; style subulate ; stigma simple. 

 Fruit ovoid, deeply S-angled, separating into five 1-seeded carpels which dehisce along 

 the inner edge. Seeds erect, broadly oblong and flattened; endosperm bony. [Name in 

 honor of G. C. Fagon, a French botanist of the seventeenth century.] 



A genus of about 18 species, natives of southern Asia, southern Europe, Africa, Chile, Mexico, and Cali- 

 fornia. Type species, Fagonia cretica L. 



1. Fagonia californica Benth. California Fagonia. Fig. 3001. 



Fagonia californica Benth. Bet. Sulph. 10. 1844. 



Fagonia laevis Standley, Proc. Biol. Soc. Wash. 24: 249. 1911. 



Fagonia cretica var. californica Engler, Veg. der Erde 9^: 731. 1915. 



Fagonia chilensis var. laevis I. M. Johnston, Proc. Calif. Acad. IV. 12; 1051. 1924. 



Stems diffusely and divaricately branched, 2-6 dm. high, glabrous and minutely spinulose on 

 the angles. Leaves 3-foIiolate, short-petioled ; leaflets lanceolate, the lateral ones oblique, 1-8 

 mm. long, glabrous or nearly so ; sepals lanceolate, spinulose-tipped, 4-5 mm. long ; petals spatu- 

 late, 5-8 mm. long. 



Rocky or gravelly ridges. Lower Sonoran Zone; Colorado Desert, and near the Mexican Boundary south 

 of San Diego, California, south to Sonora and central Lower California. Type locality: Magdalena Bay, Lower 

 California. Jan.-June. 



Fagonia californica var. glutinosa Vail, Bull. Torrey Club 22: 225. 1895. (Fagonia chilensis var. gluti' 

 nosa I. M. Johnston, Proc. Calif. Acad. IV. 12: 1051. 1924.) Stems mostly prostrate, stouter, beset, especially 

 above, by conspicuous subsessile yellowish glands; leaflets larger, the middle one often rhomboidal, 1-2 cm. 

 long. Sandy or rocky situations, Lower Sonoran Zone; northern borders of the Colorado Desert, Riverside 

 County, California, south to Sonora and Lower California. Type locality: Sonora. 



2. lARREA Cav. Anal. Hist. Nat. 2: 119. pi. 18. 1800. 



Evergreen strong-scented resinous shrubs. Leaves of a single pair of leaflets, these 

 sessile by the broad base on the rachis and simulating a 2-lobed leaf. Peduncles interstipu- 

 lar, 1-flowered. Sepals 5, caducous. Petals 5, clawed, yellow. Stamens 10, inserted on the 

 base of tlie small 10-lobed disk; filaments with a laciniate scale at the base. Ovary 5-celled, 

 about 6 ovules in each cell; styles united; stigmas 5. Fruit obovoid or globose, densely 

 white-hirsute, at length separating into five 1-seeded indehiscent nutlets. [Name in honor 

 of J. A. de Larrea, Spanish patron of science.] 



A genus of 2 or 3 species, natives of the southwestern United States, Mexico, and South America. Type 

 species, Larrea nitida Cav. 



1. Larrea glutinosa Engelm. Creosote Bush. Fig. 3002. 



Zygophyllum calif ornicum Torn & Frem. in Frem. Second Rep. 257, 1845. (Hyponym.) 



Larrea glutinosa Engelm. in Wisliz. Mem. Tour North. Mexico 93. 1848. 



Covillea glutinosa Rydb. N. Amer. Fl. 25: 108. 1910. 



Larrea tridentata var. glutinosa Jepson, Man. Fl. PI. Calif. 604. 1925. 



Schroeterella glutinosa Briq. Veroff. Geobot. Inst. Riibel 3: 664. 1925. 



Neoschroetera glutinosa Briq. Candollea 2:514. 1926. 



A much-branched shrub, 1-2 m. high, very leafy, the branches marked by black bands at the 

 joints, young branchlets silky-pubescent. Leaflets obliquely lanceolate, curved, 5-10 mm. long, 

 thick, coriaceous, dark yellowish green and resinous, silky-pubescent, becoming glabrate; petals 

 spatulate, oblong, twisted, 6-8 mm. long; fruit subglobose, 4-5 mm. broad, densely hirsute. 



A characteristic and common shrub of the Lower Sonoran Zone; Mojave Desert, California to southern 

 Utah and south through the desert regions to western Texas and northern Mexico. Type locality: 011a and Fra 

 Cristobal, New Mexico. March-June. 



This species is referred by some botanists to the closely related Chilean species, Larrea divaricata Cav. 



3. TRIBULUS [Tourn.] L. Sp. PI. 386. 1753. 



Diffusely branching prostrate herb, with pubescent stems. Leaves opposite, pinnate, 

 the alternating pairs of leaflets usually reduced or abortive. Stipules membranaceous. 

 Flowers solitary on axillary peduncles. Sepals 5, early deciduous. Petals 5, yellow or 

 rarely white. Stamens 10, hypogynous, the filaments filiform, naked. Ovary 5-celIed, 

 surrounded at the base by a 10-lobed disk; styles united, stout; stigmas 5. Fruit depressed, 

 5-angled, spinose, separating at maturity into five 3-5-seeded, bony nutlets. Seeds oblong- 

 ovate; endosperm none. [Name Latin, from the Greek triholos, a pronged instrument 

 thrown on the ground to impede cavalry. Applied by the ancients to the genus Trapa^ 



A genus of about 12 species, natives of the warm temperate and tropical regions. Type species, Tribulus 

 terrestris L. 



1. Tribulus terrestris L. Land Caltrop or Puncture Weed. Fig. 3003. 



Tribulus terrestris L. Sp. PI. 387. 1753. 



Annual, the stems much branched from the base, prostrate or ascending, 2-5 dm. long, 

 pubescent. Leaflets 5-8 pairs, oblong, inequilateral, 6-15 mm. long; petals oblong, 2-4 mm. long, 



