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 axillary 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 

 sessile, 5-celled, 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, tuber culate or spinose, separating at maturity into 5 bony 

 carpels. Seeds oblong-obovate. Endosperm wanting. 



1. T. terrestris L. A diffuse trailing 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.^Ill. — 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. br achy sty lis. 



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, obliquely elliptic or oval, 6-15 mm. long, 

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

 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, 4-7 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. 



F.\MiLY 72. RUTACEAE. 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. 



