44 2 



ZYGOPHYLLACEAE. 



VOL. II. 



Family 66. ZYGOPHYLLACEAE Lindl. Nat. Syst. 1830. 

 CALTROP FAMILY. 



Herbs, shrubs, or some tropical species trees, the branches often jointed to 

 the nodes. Leaves mostly opposite, stipulate, pinnate, or 2-3-foliolate, the leaflets 

 entire. Stipules persistent. Flowers perfect, axillary, peduncled. Sepals usually 

 5, distinct, or united by their bases. Petals the same number as the sepals, or 

 none. Stamens as many as the petals, or 2-3 times as many, inserted on the base 

 of the receptacle, the alternate ones sometimes longer ; anthers versatile, longitudi- 

 nally dehiscent ; filaments usually with a small scale at the base or near the middle. 

 Ovary 4-i2-celled ; style terminal; stigma usually simple; ovules i-numerous in 

 each cavity, pendulous, or ascending. Fruit various, dry in our species. Endo- 

 sperm of the seed copious or none ; embryo straight or curved ; cotyledons linear 

 or oblong. 



About 20 genera and 160 species, widely distributed in warm and tropical regions. 



Fruit spiny, splitting into 5 3-5-seeded segments. 



Fruit not spiny, often tubercled, splitting into 10-12 i -seeded segments. 



1. Tribulus. 



2. Kallstroemia. 



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



Herbs, mostly diffuse or prostrate, with evenly pinnate stipulate leaves and peduncled 

 axillary yellow flowers. Sepals 5, deciduous. Petals 5, deciduous. Stamens 10, hypogynous, 

 the alternate ones somewhat longer. Ovary sessile, 5-lobed, 5-celled, hairy; disk lo-lobed; 

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

 splitting into five 3-5-seeded segments. [Greek, three-pronged, Caltrop, from the resem- 

 blance of the fruit to that implement.] 



About 12 species, natives of warm and tropical regions. Besides the following typical one, 

 another occurs in the Southern States. 



i. Tribulus terrestris L. Ground Burnut. 

 Land Caltrop. Fig. 2688. 



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



Annual, pubescent, branched from the base, the 

 stem prostrate or ascending, sometimes i long or 

 more. Leaves petioled; stipules small; leaflets 4-8 

 pairs, oblong, inequilateral, opposite, short-stalked, 

 acutish or obtuse, 3"-8" long; flowers solitary, about 

 6" broad; peduncles shorter than the leaves; petals 

 oblong, about as long as the sepals; segments of the 

 fruit usually with 2 long spines, 2 shorter ones, and 

 a row of very short ones forming a crest on the 

 back, also commonly with some bristle-like hairs. 



In ballast and waste places about the eastern seaports, 

 and from Illinois to Nebraska, Arkansas, Arizona and 

 Mexico. Adventive from Europe. June-Sept. 



2. KALLSTROEMIA Scop. Introd. 212. 1777. 



Mostly annual branching pubescent herbs, the branches often prostrate, with opposite 

 stipules evenly pinnate leaves, and solitary axillary peduncled yellow flowers. Sepals usually 

 5, persistent or deciduous. Petals the same number, obovate or oblanceolate, deciduous. 

 stamens twice as many as the petals. Ovary sessile, io-12-celled ; ovule i in each cavity, 

 style long, or short, io-i2-grooved, persistent; stigma mostly io-i2-ridged. Fruit 

 io-i2-lobed not spiny, often tubercled, splitting into 10-12 i-seeded segments. [In honor of 

 Kallstroem.] 



Besides the following, ; 

 style longer than the carpel-bodies; carpel-faces scarcely wrinkled; petals 3 ^"- S " long. 



Persistent style shorter than the carpel-bodies; carpel-faces prominently wrinkled ^t^/J'-f 



2. K. hirsntissima. 



