670 ZYGOPHYLLACEAE 



lary pedicels : sepals lanceolate, 3.5 ram. long, acute, pubescent : corolla 5-10 mm. broad : 



petals fan-shaped, about 2 mm. long, commonly broader than long : stamens as long as the 



petals : filaments glabrous : ovary bristly pubescent : fruit about 1 cm. long, armed with 



straight or curved spine-like thorns. 



A native of southern Europe and the East Indies, introduced into America from New York, Florida, 

 Texas and Mexico. 



2. Tribulus cistoides L. Stems branched at the base, the branches 3-9 dm. long, 

 prostrate, spreading radially, forked: leaves 8-4 cm. long, silky: leaflets 6-16, the blades 

 firm, oblong or linear-oblong, 7-10 mm. long, apiculate, oblique, sessile : flowers on axil- 

 lary pedicels which are nearly as long as the subtending leaf or longer : sepals lanceolate, 

 8-10 mm. long, acuminate, pubescent : corolla yellow, 4-5 cm. broad : petals obovate, 

 usually about 2 cm. long : stamens about ^ as long as the petals : filaments glabrous : 

 ovary bristly-pubescent : fruit about 1 cm. in diameter, armed with more or less curved 

 spine-like thorns. 



In sandy soil, Florida to Lower California, southward through tropical America. 



2. KALLSTROEMIA Scop. 

 Herbs resembling Tribvlus. Leaves opposite or alternate : stipules very narrow. 

 Flowers solitary on axillary pedicels. Sepals 5-6, imbricated, distinct or nearly so, 

 persistent. Petals 5-6, spreading, imbricated or convolute, yellow or red, deciduous. 

 Stamens 10-12 : filaments filiform-subulate, those opposite the petals exterior and adnate 

 to the base of the petals, those of the interior series alternate with those of the outer, 

 shorter and each subtended by a small gland. Ovary sessile, 10-12-celled, without trans- 

 verse septa: styles united into an elongated column: stigmas 10-12, parallel. Ovules 

 solitary in each cavity, pendulous, anatropous or half anatropous. Fruit 10-12-angled, 

 tuberculate, at maturity separating from a thick axis into 10-12 carpels. Seeds solitary 

 in each carpel, with a membranous testa. Endosperm wanting. Caltrop. 



Sepals lanceolate, not hirsute, mainly appressed-pubeseent. 1. A', maxima. 



Sepals linear-subulate, bristly hirsute. 



Leaves and branchlets sparingly pubescent: plants slender: pedicel less than 



1..5 mm. thick under the fruit. 2. K. parviflora. 



Leaves and branchlets copiously and conspicuously hirsute : plants stout : pedi- 

 cel over 1.5 mm. thick under the fruit. 3. A', hirsutissima. 



1 Kallstroemia rndxima (L. ) T. & G. Stem branched at the base, the branches 

 radially spreading, usually prostrate, 1-6 dm. long or longer, more or less forked, rather 

 appressed-pubeseent, succulent : leaves sparingly pubescent : leaflets mostly 6-8, the blades 

 of the terminal pair 9-18 mm. long : sepals lanceolate, sometimes narrowly so in age, 3-4 

 mm. long, rather appressed-pubeseent : petals 6-8 mm. long : fruit 7-10 ram. long, the 

 conic beak somewhat longer than the body. 



In waste places and sandy soil. Gulf States. Also in tropical America. 



2. Kallstroemia parviflora Norton. Similar to K. maxima in habit, but with more 

 spreading pubescence. Leaves thinly pubescent : leaflets 6-8, the blades of the terminal 

 pair 6-13 mm. long : sepals linear-subulate, 4.5-6 mm. long, bristly hirsute : petals 6-8 

 mm. long : fruit 10-12 mm. long, or rarely slightly smaller, tlie slender beak somewhat 

 longer than the body. 



In dry soil, Mississippi to Arizona and Mexico. 



3. Kallstroemia hirsutissima Vail. Similar to the two preceding species, but stouter. 

 Leaves copiously and conspicuously pubescent : leaflets mainly 6-8, shaggy pubescent at 

 least beneath, the blades of the terminal pair mostly 10-23 mm. long : sepals linear-subu- 

 late, 3.5-4.5 mm. long, bristly hirsute: petals 5-7 mm. long: fruit 6-8 mm. long, the 

 conic beak commonly as long as the body or somewhat shorter. 



On plains and prairies, Kansas and Colorado to Texas, New Mexico and Mexico. 



3. COVILLEA Vail. 



Heavy-scented evergreen shrubs, often excreting an acid resin. Leaves opposite : 

 blades 2-foliolate or pinnate : stipules present : leaflets opposite, with inequilateral sessile 

 blades. Flowers terminal on pedicels arising from between the stipules. Sepals 5, imbri- 

 cated. Petals 5, yellow, imbricated, short-clawed, surpassing the sepals. Disk 10-lobed. 

 Stamens 10, inserted below the disk : filaments filiform, each bearing a wing-like, 2-cleft 

 scale. Ovary 5-celled, short-stalked, pubescent. Ovules 6 in each cavity, pendulous. 



