312 PROCEEDINGS OF THE AMERICAN ACADEMY. 



legume about 3-jointed, finely pubescent upon the valves and strongly 

 setose on the margin. — Benth. in Hook. Lond. Jour. Bot. v. 85, & 

 Trans. Linn. Soc. xxx. 392. — Borders of Oaxaca and Chiapas, Nelson, 

 no. 2858 ; Guatemala, Skinner, ace. to Benth., J. D. Smith, nos. 3758, 

 6132; Costa Rica, Ujaras, Oersted, ace. to Hemsl. 



9. M. Pittieri, Micheli. Pinnse always 2 pairs; leaflets 5 to 6 

 pairs, ovate, ciliate : infra-stipular spines recurved, caducous : peduncles 

 axillary, solitary, exceeding the petioles : bracts nearly or quite as long 

 as the corolla. — Bull. Soc. Bot. Belg. xxx. 294 (whence description is 

 compiled). — Near Rio Jesus Maria Puntarenas, Costa Rica, Pittier, 

 no. 502. Not seen by the writer. 



*+ ••-* Leaflets oblong. 

 = Margin of legume bearing very short recurved hairs ; valves pubescent and 



often strigillose. 



10. M. affinis, Robinson. Pinnce 1 pair; leaflets 8 to 12 pairs, 

 acutish : peduncles shorter than the petioles. — Bot. Gaz. xvi. 341. — 

 Grassy land near Mazatlan, W. G. Wright, nos. 1218, 1265; hillsides 

 near Tequila, Pringle, no. 5453; Colima, Palmer, no. 131 (coll. of 

 1897) ; wet soil near Cuernavaca, Morelos, Pringle, no. 6662. 



= = Valves of the legume glabrous ; margins setose with straight spreading 

 bristles : pinnae 1 or more commonly 2 approximate pairs. 



1 1 . M. pudica, L. The well known sensitive plant of cultivation, 

 very variable as to jjubescence : occasional scattered spines as well as 

 the infra-stipular usually present. — Spec. i. 518; Benth. Trans. Linn. 

 Soc. xxx. 397, where extensive synonymy is given. — Common through- 

 out tropical America from S. Mexico southward ; Orizaba, Bourgeau, 

 no. 2400; Vera Cruz, Bourgeau, no. 1759, C. L. Smith, no. 999, Nelson, 

 nos. 159, 393; Costa Rica, /. D. Smith, no. 5767; Honduras, J. D. 

 Smith, no. 5219, Niederlein; Panama, Fendler, no. 96, Seemann, no. 

 102. (Also extensively naturalized in the warmer countries of the Old 

 World and said to be spontaneous in some parts of our Southern States.) 



•I- -I- Stems decidedly ligneous. 



++ Spines infra-stipular or scattered: pinnje 1 or "2 pairs: fruit (where known) 



rather narrow, not exceeding 8 mm. in breadth. 



= Leaflets 13 to 25 mm. long. 



a. Branchlets and peduncles scabrous-pubescent. 



12. M. tricephala, Cham. & Schlecht. Spines straight: leaf- 

 lets 10 to 15 pairs, ovate-oblong, 1-2-nerved, glabrous above, strigose 

 beneath,. 1.2 cm. long. — Linncea, v. 591; Benth. Trans. Linn. Soc. 



