DIADELPUIA. DECANDRIA. 95 



pressed, carinate, villous on the upper side. 

 Suture of the legume naked. 



Stem scandent or diffuse; petiole many-leaved, leaflets 

 and stipules large; peduncles axillary, i or many-flower- 

 ed. 



Species. 1. P. mariti7num. Abundant on the shores 

 of Lakes Erie, Huron and Michigan, but differs from the 

 European species m having a pubescent legume. 



At present there are but 4 species of this genus, indige- 

 nous to Europe and Egypt, but the habitat of the garden 

 pea (P, sativum) like that of many other important plants 

 in human diet, appears not to have been ascertained. 



495. OROBUS. L, (Bitter-Yetch.) 



Style linear. Corolla long. Calicc obtuse at 

 the base; upper segments deeper and mostly 

 shorter. 



Stem herbaceous, often erect; leaves conjugate, biju- 

 gate or pinnate, mostly terminated by a short and straight, 

 undivided, setiform tendril; stipules mostly semisagittate; 

 flowers racemose, axillary and terminal. 



Species. 1. O. * dispar. Leaves uaequally pinnate, 6 

 to 8 pair, leaflets linear, obtuse; stipules simply ovate, 

 acute; racemes sessile, filiform, 2 or 3 together; segments 

 of the cahx equal, the uppermost indenture deeper and 

 wider. Hab. On arid hiils near Fort Mandan. Flowering 

 in JuHe. Obs. This and the following species differ very 

 remarkably from the usual habit of the genus, but analy- 

 tically compared with Orobiis sylvaiicus, now before me, 

 they appear to be inseparable congeners. Root perennial. 

 Stems numerous, decumbent, branched, terete below, an- 

 gular above, rigid, a little pubescent in common with the 

 rest of the plant. Racemes about the length of the leaves; 

 flowers remote, ochroleucous; thecalix obtuse at the base, 

 dentures subacuminate; wings longer than the carina; 

 style and minute stigma nearly smooth; legume many- 

 seeded, smooth and flat, acute and curved at the point, at- 

 tenuated at the base; seeds 6 to 8, about the size of small 

 Vetches. The habit of this plant is more that of Astraga- 

 IziS than Orobus. 



2. * longifoUus. Sericeously villous; leaves ternate and 

 bijugate, uppermost simple,' leaflets very long and fiU- 

 forn)ly linear; stipules undivided, ovate-lanceolate, acumi- 

 nate; racemes pedunculate, filiform, often solitary, shorter 

 than the leaves; the 2 upper dentures of the calix shorter. 



