ADDENDA. 
Pennsylvania Water Cress. 
From six inches to a foot high. Flowers white, small. 
Whole plant peperish. In low meadow-grounds, and near 
rivulets and springs; common. Perennial. May. 
DIADELPHIA, DECANDEIA. 
To genus Lathyrus^ No. 314. vol. 2. page 72, 
add the following species : 
No. 2. Lathyius venosus; stem naked, four-an- 
gled ; stipules semi-sagittate, ovate, acuminate ; 
folioles very numerous, nearly alternate, ovate, 
obtuse, mucronate, veined; peduncles shoiter 
than the leaf, 5-10 flowered. — Willd. and Pursh. 
Flowers purple. Perennial. July. Within the limits of this 
work; Mr. Collins. 
To Andromeda paniculata add the following 
synonym : 
Andromeda ligustrina, Muhl. Cat. 2d ed. 
Vaccinium ligiistrinum, L. 
SYNGENESIA, ^QUALIS. 
To genus Cnicus, No. 306. p. 94. vol. 2, add the 
following species : 
5. Cnicus arvensis ; leaves sessile, pinnatifid, some- 
what smooth, dliate, very spinous ; stem panicu- 
late; calices ovate, mucronate; scales broad- 
lanceolate, adpresscd, woolly on the margin. — 
Pursh. 
Carduus arvensis, Smith, 
