392                                       APPENDIX.
XV. CLASS MONADELPHIA.
* '
66.  Geranium robertianum, Nutt. Gen. II. p. 80. Common in Pennsylvania.
XVI. CLASS DIADELPHIA.
67.  Petalostemum candidum, Pursh, p. 461. Indigenous to the western country.
68.  Petalostemum violaceum, Pursh, p. 461. Likewise peculiar to the western countries.
Both these plants are well described by Michaux, and figured on his Tab. 37, f. 1 and 2.
69.  Corydalis glauca, Pursh, p. 463. Common among rocky hills.
70.  Amorpha canescens, Nutt. Gen. II. p. 92. Peculiar to the north-western country.
71.  Lathyrus palustris, Pursh, p. 471.
Found in Canada by Michaux, and common in Europe.
72.  Lathyrus venosus, Pursh, p. 471. Common in the Pennsylvania mountains.
73.  Vicia *tridentata, L. v. Schw.
The single, but good specimen of this plant, does not agree,, I think, with any one described by American authors or Persoon. I therefore venture to point it out by the above name, taken from the singular form of its stipules. It approaches nearest to V. sylvatica.
Stem flexuosely bent, subpubescent, angular and much grooved. Peduncles equal to the leaves. Leaflets numerous, sometimes alternate, sometimes opposite, narrow, oblong, entire, obtuse, with a short mucro, sprinkled with hair on the upper surface, and almost canescently so on the under. Stipules, upper ones lanceolate, long, acuminate,