62 CLASS IV. ORDER I. 



numerous, large, and crowded, oblong heart shaped, acQte, 

 smooth, with numerous fleshy veins of a paler color. They 

 grow from the root on long petioles, hollowed in front, and furn- 

 ished with large oblong sheaths. They continue to increase in 

 size for a month or two after the flowering period is past, and 

 are conspicuous in summer in every meadow, swamp, and brook 

 side. 



The odor depends on a volatile principle not separable by dis- 

 tillation. There is besides an acrid principle, which remains in 

 the root when dried. This plant has been found useful in asth- 

 ma and some other diseases, but is not safe in large quantities. 



66. LUDWIGIA. 

 LuDWiGiA ALTERNiFOLiA. L. Common Ludwigia. 



Erect, smooth ; leaves alternate, lanceolate, pale 

 beneath; peduncles axillary, one llowered ; capsules 

 globose, four cornered, crowned with the calyx. 



Sljn. LXJDWIGIA MACROCARPA. Mx. 



Stem erect, round, with a tough, fibrous bark. Leaves scat- 

 tered, on very short petioles, lanceolate, entire, pale, and veined 

 underneath. Flowers on short, axillary stalks. Calyx of four 

 ovate acute leaves, investing the germ at base, which is square^ 

 with winged angles. Petals orbicular, yellow. — Shady swamps, 

 Cambridge. — July, August. — Perennial. 



67. ISNARDIA. 



IsNARDiA PALusTRis. L. IsnarcUcl. 



A weed swimming in ditches and streams of water, or creep- 

 ing on wet grounds. Leaves opposite, oval or ovate, smooth. 

 Flowers small, sessile in the axils of the leaves, without beauty. 

 -—June. — Annual. 



68. SWERTIA. 



SwERTiA PusiLLA. Ph. Alpine stccrtia* 



Corolla rotate, twice as long as the calyx; stem 

 simple, one flowered ; leaves oblong. 



A small plant, hardly exceeding an inch in height with a blue 

 flower of considerable size, having the habit of a Gentian. It 



