464 



29. TEPHROSIA 



Plants perennial, herbaceous; stems either sympodial and the 

 racemes appearing lateral, opposite the leaves, or monopodial and the 

 racemes terminal and axillary; herbage not punctate; leaves odd-pin- 

 nate, the leaflets few to numerous ; stamens more or less united ; pods 

 linear, flat, several-seeded. 



Although some of the species of this genus are a source of 

 rotenone, an extensively used insecticide, the Arizona species ap- 

 parently contain little or none of this substance. They are, however, 

 suspected of being poisonous. 



Key to the species 



1. Stem sympodial; racemes appearing lateral, opposite the leaves, few-flowered, 

 the flowers very scattered; leaflets 5 to 11, linear to oblanceolate, up to 

 8 mm. wide but usually much narrower; corolla 8 mm. long, rose purple; 

 pubescence of the herbage strictry appressed (strigose) ; plant herbaceous. 



1. T. PURPUREA. 



1. Stem monopodial; racemes terminal and axillary; leaflets commonly more than 

 11; corolla more than 10 mm. long; plants suffruticose (2). 



2. Stems finely strigose-canescent; leaflets narrowly elliptic or oblanceolate, 

 not more than 8 mm. wide, glabrous above; racemes elongate, narrow, 

 loosely flowered, many of them axillary; blades of the petals rose purple; 

 pods glabrous, 5 to 6 mm. wide 2. T. leiocarpa. 



2. Stems with spreading as well as short appressed hairs; leaflets elliptic, oblong, 

 or subspatulate, often more than 8 mm. wide, pubescent on both faces; 

 racemes short, broad, densely flowered, all or nearly all terminal; blades 

 of the petals whitish, more or less tinged with purple; pods pilose, 3 to 4 

 mm. wide 3. T. leucantha. 



1. Tephrosia purpurea (L.) Pers., Syn. PI. 2: 329. 1807. 



Cracca purpurea L., Sp. PL 752. 1753. 

 Tephrosia tenella A. Gray, PI. Wright. 2: 36. 1853. 

 Cracca tenella Rose, Contrib. U. S. Natl. Herbarium 12: 271. 

 1909. 



Pinal, Cochise, Santa Cruz, and Pima Counties, 4,000 to 6,000 (?) 

 feet, slopes and mesas, usually in partial shade, May to September. 

 Texas, southern Arizona, and Mexico; widely distributed in the 

 tropics of both hemispheres. 



2. Tephrosia leiocarpa A. Gray, PL Wright. 2: 36. 1853. 



Cracca leiocarpa Kuntze, Rev. Gen. PL 1: 175. 1891. 



Sonoita Valley, Patagonia Mountains, Sycamore Canyon near 

 Ruby (Santa Cruz County), Baboquivari Mountains (Pima County), 

 4,500 to 5,500 feet, August and September. Southern Arizona and 

 northern Mexico. 



A roundish shrub, about 1 m. high. 



3. Tephrosia leucantha H. B. K., Nov. Gen. et Sp. 6: 460. 1824. 



Cracca leucantha Kuntze, Rev. Gen. PL 1: 175. 1891. 

 Cracca thurberi Rydb., North Amer. Fl. 24: 165. 1923. 



Cochise, Santa Cruz, and Pima Counties, 5,000 to 6,000 feet, dry 

 slopes among live oaks, August and September. Southern Arizona 

 and Mexico. 



