352 



ZYGOPHYLLACEAE. 



[VOL. II. 



i. TRIBULUS L,. Sp. PI. 387. 1753. 



Herbs, mostly prostrate, with evenly pinnate leaves and peduncled axillary yellow 

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

 what longer. Ovary sessile, 5-lobed, 5-celled, hairy, the hairs erect; style short; stigma 5- 

 ridged; ovules 3-5 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, natives of warm and tropical regions. Besides the following, another occurs 

 in the southwestern States. 



i. Tribulus terrestris L,. Ground Bur- 

 nut. Land Caltrop. (Fig. 2267.) 



Tribulus terrestris L. Sp. PL 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, peduncled; 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 sea- 

 ports, and in central Nebraska. Fugitive 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, decidu- 

 ous. Stamens twice as many as the petals. Ovary sessile, io-i2-cclled; ovule I in each 

 cavity, pendulous; style long, or short, io-i2-grooved, persistent; stigma mostly 10-12- 

 ridged. Fruit io-i2-lobed, not spiny, often tubercled, splitting into 10-12 i-seeded segments. 

 [In honor of Kallstroem.] 



About 10 species, of wide distribution in warm and tropical regions. Besides the following, 3 

 others occur in the southern and western States. 



i. Kallstroemia maxima (L/.) T. & G. 

 Greater Caltrop. (Fig. 2268.) 



Tribulus ma.vimus L,. Sp. PL 387. 1753. 

 Kallstroemia maxima T. & G. Fl. N. A. i: 213. 1838. 



Annual, branches slender, prostrate, 6'-l8' long. 

 Leaves short-petioled; stipules subulate, shorter than 

 the petioles; leaflets 3-5 pairs, oval, or oblong, inequi- 

 lateral, acute or obtuse at the apex, rounded or subcor- 

 date at the base, 4"-io" long; peduncles slender, 6' / -2 / 

 long in fruit; flowers i' broad, or less; sepals linear- 

 lanceolate, very pubescent, persistent, shorter than the 

 petals; fruit ovoid-conic, about 3" in diameter, about as 

 long as the stout persistent style, the segments tuber- 

 cled. 



In dry soil, Kansas to Georgia, Florida and Texas. Also 

 in tropical America. April-Sept. 



Family 54. RUTACEAE Juss. Gen. 296. 1789. 



RUE FAMILY. 



Trees or shrubs, rarely herbs, with heavy-scented and glandular-punctate 

 foliage, alternate or opposite mainly compound exstipulate leaves, and (in our 

 species) polygamo-dioecious generally cymose flowers. Sepals 4-5, or none. 

 Petals 4-5, hypogynous or perigynous. Stamens of the same number, or twice 

 as many, distinct, inserted on the receptacle; anthers 2-celled, mostly versatile. 

 Disk annular. Pistils 2-5, distinct, or i and compound of 2-5 carpels, inserted 



