CALTROP FAMILY 539 



3. TRIBULUS L. Bur-nut. 



Diffuse herbs, with weak, often prostrate, stems and branches. Leaves 

 abruptly pinnate, opposite. Stipules lanceolate or subulate, membranaceous. 

 Flowers solitary on a.xillary peduncles. Sepals 5, lanceolate, herbaceous, soon 

 caducous. . Petals 5, obovate, yellow, orange, or rarely white, spreading, decidu- 

 ous. Stamens 10, hypogynous; filaments filiform, naked, the 5 inner alternate 

 with the petals, shorter than the outer, subtended by a small gland. Ovary 

 sessQe, 5-celIed, surrounded at the base by an urceolate 10-lobed disk. Styles 

 united into a short stout column; stigmas 5, more or less connate. Fruit de- 

 pressed, 5-angled, tuberculate or spinose, separating at maturity into 5 bony 

 carpels. Seeds oblong-obovate. Endosperm wanting. 



1. T. terrestris L. A diffuse traihng annual herb ; stems hirsute and slightly 

 swollen at the nodes; leaflets about 5-7 pairs, somewhat oblique, oblong or 

 elliptic, 3-13 mm. long; petals obovate, about 4 mm. long, light yellow; carpels 

 5, bony, each with 2 divergent stout spines and 2 or more smaller ones, sparingly 

 hispid. Waste places and sandy soil: S.C. — -111. — -Neb. — Ariz.; Mex. and W. 

 Ind.; nat. from Eu. Plain — Son. 



4. KALLSTROEMIA Scop. Caltrop. 



Diffuse and branching herbs. Stems procumbent. Leaves opposite, abruptly 

 pinnate, the terminal pair larger. Flowers solitary, orange or yellow. Peduncles 

 axillary. Sepals 5 or 6, mostly persisting. Petals 4-6, obovate or obcordate, 

 spreading, caducous. Stamens 10 or 12, hypogynous; filaments filiform, those 

 opposite the petals adnate to the petals, the alternate ones smaller and sub- 

 tended externally by a small gland. Ovary sessile, 8-12-celled, without trans- 

 verse septa; styles united, columnar, or subulate from a conic base; stigma capi- 

 tate; fruit roughened or tuberculate, separating at maturity into 8-12 bony, 

 indehiscent, 1- rarely 2-seeded tuberculate nutlets, leaving a more or less per- 

 sistent thick styliferous central axis. 



Plant sparingly pubescent or glabrate; petals 3-5 mm. long; beak much shorter than the 

 body of the fruit. 1. K. brachystylis. 



Plant densely hirsute; petals 5-6 mm. long; beak slightly shorter than the body. 



2. K. hirsutissima. 



1. K. brachystylis Vail. A profusely branched annual; stems 2-3 dm. long 

 or more, very brittle; leaflets 3-4 pairs, obUquely elliptic or oval, 6-15 mm. long, 

 slightly falcate, ciliate on the margins; sepals lanceolate, caducous; petals 4r-5 

 mm. long, orange to pale yellow, sometimes shorter than the sepals; fruit minutely 

 pubescent; beak persistent, glabrous, 1-2 mm. long; nutlets with rounded tuber- 

 cles on the back, strongly reticulate on the faces. Sandy soil: N.M.— s Colo. — 

 L. Calif.; Mex. Son. 



2. K. hirsutissima Vail. A much branched annual; branches stout, trail- 

 ing, 4r-7 dm. long, appressed cinereous-pubescent and hirsute with longer spread- 

 ing hairs; leaflets 3-4 pairs, elliptic, 8-20 mm. long, shaggy-hirsute, at least 

 beneath; sepals linear-lanceolate, 4-6 mm. long; petals obovate-oblong, 5-6 mm. 

 long, yellow or orange, fading whitish, retuse; fruit canescent-strigose; beak 

 pubescent, conic at the base, 3-4 mm. long; carpels 10. Sandy soil: Tex. — 

 Kans. — Colo. — Mex. Son. 



Family 72. RUTACJdAE. Rue Family. 



Aromatic trees or shrubs, with secreting glands in the foliage. Leaves 

 mostly digitately or pinnately compound; leaflets usually inequilateral. 

 Flowers perfect, polygamous or dioecious. Calyx with 3-5 lobes or sepals, 

 rarely wanting. Petals 3-5, imbricate. Stamens as many as the petals or 

 twice as many, sometimes more, inserted on a hypogynous disk. Gynoe- 

 cium of 1-5, or more, free or united carpels. Fruit various, of follicles, a 

 capsule, samara, or drupe. 



