310 PROCEEDINGS OF THE AMERICAN ACADEMY. 
Var.? panamensis, Benru. 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 MM. sensitiva). 
++ ++ 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. sensittva, L. Spines of stem numerous (rarely few), somewhat 
4-seriate, very short, recurved: petioles copiously armed; leaflets — 
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 
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 aggregated in long terminal almost naked racemes.— H B. a 
Willd. Spec. iv. 1030; Kunth, Mimos. 2,t.1. JZ 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; Sinaloa, Rose, no. 1731 (peculiar form with broad very ones 
leaflets) ; Jalisco, Palmer, no. 693 (coll. of 1886); Orizaba, F. Miller, 
no. 172, Bourgeau, no. 2861; Oaxaca, Nelson, nos. 792, 204 » 
L. C. Smith, no. 792; Vera Cruz, Nelson, nos. 63, 479; Huastects 
Ervendberg, no. 1; Guatemala, Hayes, J. D. Smith, nos. 300, _ 
6118 (in part passing to var. floribunda); Costa Rica, Ocrsted no. 10; 
«SD. Smith, nos. 5765, 8975, Pittier, nos. 28, 1279, 1279 b, 1447, 301% 
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