200 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



compressed, with incrassate sutures, 2-valved, valves with a prominent nerve on both 

 sides near the margin, or winged near the lower suture; seeds obliquely oblong. Twin- 

 ing or prostrate herbs or undershrubs; leaves pinnate; leaflets 3, rarely 1, 5, or 7, some- 

 times so close together that they appear digitate; stipules persistent, striate; flowers 

 showy, often large, whitish, rose-colored, violet, or bluish, on axillary peduncles, 1 to 

 numerous; lower bracts of the same form as the stipules, in pairs or connate above, 

 bearing 1 or 2 flowers in the axils; bracteoles appressed to the calyx, striate, larger than 

 the bracts. 



The genus Centrosema strongly resembles Glitoria in habit, but can be distinguished 

 from it by the spurred standard and the much shorter calyx. 



KEY TO THE SPECIES. 



Upper calyx segments much shorter than the tube. 



Leaves 16 to 27.5 cm. long, turning black in drying; terminal 

 leaflet 8.5 to 12 cm. long, broadly ovate; bracteoles ovate, 

 twice as long as the calyx; calyx teeth very short, unequal; 

 pod 15 cm. long, 11 to 13 mm. wide; ribs of the legume 

 valves prominulous, 3.3 mm. distant from the margin; 

 corolla white, variegated with bright purple and yellow. 1. C. plumieri. 



Upper calyx segments longer, rarely a little shorter, than the tube. 



The upper calyx segments equal to the tube, connected below 

 the summit, inferior calyx lobe longer than the tube; leaf- 

 lets 5 to 7.5 cm. long, 2.5 to 3.7 cm. wide, ovate; bracteoles 

 ovate, as long as the calyx; pod 5 to 6.5 mm. wide, the ribs 



of the legume valves 2.2 mm. from the margin. 2. C. pubescens. 



The upper calyx segments longer than the tube, free or con- 

 nate at the base; leaflets 3.5 to 5 cm. long, 1.8 to 2.5 cm. 

 wide; bracteoles ovate, somewhat exceeded by the calyx; 

 pod 4.4 mm. wide; ribs of the legume valves juxtamarginal. 3. C. virginianum. 



1. Centrosema plumieri (Turp.) Benth. 

 (Urban, 300.) 



Stem twining, suffrutescent at the base; peduncle 2 or 3- (rarely 5 or 6-) flowered; 

 calyx 6.5 mm. long; standard spurred above the calyx, 4 cm. in diameter, orbicular; 

 wings narrowly oblong, falcate, shorter than the standard; keel large, broader and 

 shorter than the wings; legume 15 cm. long, 1.3 cm. wide, erect or slightly curved. 



Near Bayamon in thickets. Cuba, Jamaica. Haiti, St. Thomas, St. Kitts (Grisebach i, 

 Antigua, Martinique, St. Vincent, Grenada, Trinidad (Grisebach). Indigenous in 

 tropical America. 



Centrosema plurmeri is common on fences in the West Indies. The leaflets and 

 flowers are larger than those of the other two species of Centrosema found in Porto Rico. 

 The roots contain a volatile oil and a resin that is much used in popular medicine. 



Local name, conchita <l< Plumier (Cook and Collins). 



2. Centrosema pubescens Benth.b 



(Urban, 300.) 



Stem twining; flowers few, at the apex of the peduncle, yellow; calyx 6.5 to 11 mm- 

 deep; standard 2.5 cm. in diameter; keel wide, incurved; pod 15 to 20 cm. long, 3 to 

 6.5 mm. wide. 



a Cook and Collins, p. 94, as Bradburya plumieri. 

 ''Cook and Collins, p. 94, as Bradburya pubescens. 



