TETRAXDBIA. MOll^OOTNIA. 103 



Species. 1. F. Walteri. From Canada to Carolina. 

 In the dry and open woods of western Pennsylvania and 

 New-York, in certain localities abundant. It is ti.ere 

 called Cohimbo-root, and appears to be a tonic no way in- 

 ferior to the Gentiana lutea. 



A genus peculiar to the United States. 



152. OBOLx\RIA. L. 



Calix 0, or in the form of 2 bractcs. Corolla 

 campanulate, 4-clet't, segments entire, (the mar- 

 gin sometimes crenately torn.) Stamina equal, 

 proceeding from the clefts of the corolla. Stig- 

 ma emarginate. Capsule ovate, 1 -celled, 2-valv- 

 cd, many-seeded; seeds minute. 



A very small vernal plant, with a simple stem, and op- 

 posite leaves; flowers sessile, terminal and marcescent, 

 collected by pairs or by threes towards the summit of the 

 stem; stigTna minutely bifid. (Bitter, and probably tonic ) 



Species. 1. O. virginica. Perennial? about 3 or 4 

 inches high, with a small branching root; leaves thick, 

 g"reen, almost carnose, frequently purplish on the un- 

 der side; flowers bluish-while, subtended by foliaceous- 

 bractes. 



Peculiar to North America. — In the neig-hbourhood of 

 Philadelphia, rare. — Ur. W. P. Barton. Near West Ches- 

 ter, (Pensylvania.) — Dr, W. Darlington. Abundant in 

 the shady forests of Lake Erie, (Ohio.) In the revision 

 and arrangement of this genus, which distinctly apper- 

 tains to the Natuial Order Gentianece o^ ixxasx^n, I amhap- 

 py to have been corroborated by the interesting remarks 

 of Ur. W. Darlington, who for four years in succession 

 I has been in the habit of examining the Obolaria. 



ff Flowers tetrapetalous* 



153. AMMANNIA. Z. 



Calix 1 -leaved, striate, 8-toofhed, inferior. 

 Corolla of 4 petals, or none, inserted upon the 

 calix. Capsule 4-celled, many=seeded. 



Siibaquatic herbs with opposite leaves; flowers very 

 small, axillary, sessile, or shortly pedunculate, opposite, 

 and sometimes almost verticillate. In ^1. indica, and ^. 

 vertkillaiay the calix is 4-toothed, and shorter than the 

 capsule. 



