670 ZYGOPHYLLACEAE 
lary pedicels : sepals lanceolate, 3.5 mm. 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 3-4 em. 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 em. long: stamens about i 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 Tribulus. 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-pubescent. 1. K, 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- MAL Ses 
cel over 1.5 mm. thick under the fruit. 3. K. hirsutissima. 
1 Kallstroemia máxima (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-pubescent, 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-pubescent: petals 6-8 mm. long: fruit 7-10 mm. long, the 
conic beak somewhat longer than the body. 
In waste places and sandy soil, Gulf States. Also in tropical America. 
2. Kallstroemia parvifldra Norton. Similar to K. marima 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, the slender beak somewhat 
longer than the body. 
In dry soil, Mississippi to Arizona and Mexico. 
3. Kallstroemia hirsutíssima 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-subo- 
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, in 
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. 
