310 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Var. ? panamensis, Benth. Annual or a slender undershrub, 

 armed with scattered recurved spines : leaflets oblong, narrower than 

 in the typical form, the larger 18 mm. long, 6 mm, broad. — Trans. 

 Linn. Soc. xxx. 391. — Panama, in meadows near Nata, Seemann, no. 

 98 (in herb. Gray) ; also at Boruca, Costa Rica, Pittier, no. 4554 (dis- 

 trib. as M. sensitiva). 



++ -M- Armed shrubs with ovate-lanceolate or ovate-oblong, acutely or at least 

 bluntly pointed leaflets : margin of legume bearing long straight spreading 

 spinescent bristles; valves sparingly covered with weak straight appressed 

 bristles. 



M. SENSITIVA, L. Spines of stem numerous (rarely few), somewhat 

 4-seriate, very short, recurved: petioles copiously armed; lea.flets 

 lanceolate, thickish, glabrous or puberulent above, appressed-setulose 

 beneath. — Spec. i. 518 (Breyne, Cent. 31, t. 16); Benth. Trans. Linn. 

 Soc. xxx. 390, & in Mart. FI. Bras. xv. pt. 2, 305. — Brazil, Claussen 

 (Mart. Herb. Fl. Bras.) 1079 (in herb. Gray). This S. American 

 species has been credited to Costa Rica by Micheli (Bull. Soc. Bot. 

 Belg. xxx. 294) on the basis of Pittier's nos. 23, 1279, 1279 bis, 1447, 

 1448, 3013, but the writer, who (through the kindness of Captain J. 

 Donnell Smith) has seen specimens of all these numbers except 1448, 

 would regard them as mere forms of M. albida, H. & B. 



++++++ Armed shrubs with leaflets mostly acutish but sometimes rounded at the 

 apex : legumes finely strigillose with short appressed or often incurved hairs 

 both on margin and valves. 



7. M. albida, H. & B. A polymorphous species: stems armed 

 with scattered (not seriate) spines, and covered with spreading usually 

 copious often tawny hairs : leaflets acutish rarely obtuse or rounded, cov- 

 ered on both surfaces with fine white appressed hairs which are denser and 

 often mixed with strigose bristles beneath : pedunculate heads axillary 

 or affSfresfated in long terminal almost naked racemes. — H. & B. in 

 Willd. Spec. iv. 1030; Kunth, Mimos. 2, t. 1. 31. sensitiva, Lodd. Bot. 

 Cab. t. 249; Micheli, Bull. Soc. Bot. Belg. xxx. 294; not L. — S. 

 Mexico and Centr. Am., southward to Peru. San Luis Potosi, Pringle, 

 no. 3970 ; Siualoa, Rose, no. 1731 (peculiar foi-m Avith broad very obtuse 

 leaflets) ; Jalisco, Palmer, no. 693 (coll. of 1886) ; Orizaba, F. MilUer, 

 no. 172, Bourgeau, no. 2861; Oaxaca, Nelson, nos. 792, 2070, 

 L. C. Smith, no. 792 ; Vera Cruz, Nelson, nos. 63, 479 ; Iluasteca, 

 Ervendherg, no. 1 ; Guatemala, Hayes, J. D. Smith, nos. 300, 2307, 

 6118 (in part passing to var. jlorihunda) ; Costa Rica, Oersted no. 10, 

 /. D. Smith, nos. 5765, 8975, Pittier, nos. 23, 1279, 1279 b, 1447, 3013, 



