468 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



leaflet; flowers axillary, solitary or in pairs, short-pediceled, small and 

 inconspicuous; pods as in Cracca; seeds quadrangular, sharply con- 

 stricted at the middle. 



1. Sphinctospermum constrictum (S. Wats.) Rose, Contrib. U. S. Natl. 

 Herbarium 10: 107. 1906. 



Tephrosia constricta S. Wats., Amer. Acad. Arts and Sci. Proc. 

 24: 46. 1889. 



Santa Cruz and Pima Counties, 2,500 to 4,000 feet, not common, 

 open sandy places, July to September. Southern Arizona, Sonora, 

 and Baja California. 



37. SESBANIA 



Plant annual, glabrous; stems tall, erect, sparingly branched, leafy; 

 leaves bright green, elongate, pinnate, the leaflets numerous, narrow, 

 oblong or elliptic ; flowers in axillary few-flowered racemes ; corolla pale 

 yellow, usually streaked and spotted with brown purple; pods long, 

 very slender, dehiscent, with cross partitions between the numerous 

 oblong seeds. 



1. Sesbania exaltata (Raf.) Rydb., North Amer. Fl. 24: 204. 1924. 



Darwinia exaltata Raf., Fl. Ludov. 106. 1817. 

 Sesban sonorae Rydb., North Amer. Fl. 24: 205. 1924. 



Bottom lands along the Colorado River, Yuma County, and occa- 

 sionally escaped from cultivation elsewhere in irrigated districts of 

 southern Arizona, August to October. Missouri to Florida, Texas, 

 southwestern Arizona, southeastern California, and northwestern 

 Mexico. 



Often planted as a soil-improvement crop on farms in irrigated sec- 

 tions of the Southwest and as a cover crop in citrus orchards. It is 

 a fiber plant producing lustrous, smooth, and very strong filaments, 

 which are used by the Yuma Indians for nets and fishlines. The 

 stems reach a height of 3 m. (10 feet). 



38. SWAINSONA 



Plant herbaceous, perennial, glabrous or nearly so; flowering stems 

 from creeping rootstocks, tall, erect, leafy, strictly branched above; 

 leaves pinnate, the leaflets numerous, thin, narrowly elliptic or oblan- 

 ceolate, about 1 cm. long; flowers in numerous loose axillary racemes, 

 large and showy; corolla dull red; pods large, bladderlike, nearly 

 globose, long-stipitate, with thin papery walls, indehiscent or tardily 

 and irregularly dehiscent. 



1. Swainsona salsula (Pall.) Taubert in Engl, and Prantl, Pflanzen- 

 fam. III. 3: 281. 1894. 



Phaca salsula Pall., Reise 3: 747. 1776. 

 Sphaerophysa salsula DC, Prodr. 2: 271. 1825. 



Navajo County, at Winslow (Peebles 9595, 11998), and Holbrook 

 to Winslow (McKelvey 4565), May and June. Here and there in the 

 western United States, introduced from Asia. 



The plant is known to the writers only in a single roadside colony at 

 Winslow, which has not increased greatly in size during the past 5 

 years. Related species are reputed to be poisonous. The plant 

 might easily be mistaken for a large bladdery-fruited Astragalus 



