110 ONAGRACE.iE. 



(Torr. 4- Gfr.) ^. (Pursh.)Stem about a foot high, slender, smooth and pur- 

 plish towards the summit. Flowers small, orange-yellow, in a terminal some- 

 what crowded spike. Perhaps not distinct from the next 



Orange-flowered Evening Primrose. 



7. (E. pumila Linn. : minutely pubescent ; stem ascending ; leaves lan- 

 ceolate or oblong-lanceolate, mostly obtuse, attenuate at base, entire, the 

 radical ones obovate-spatulate ; petals obcordate; capsule oblong-clavate, 

 nearly sessile, 8-angled. (E. pusilla Mich. 



Dry fields. Hudson's Bay to Car. July. (g). (Torr. fy Gr.)Stem 612 

 inches high, mostly simple. Flowers small, pale yellow, in a loose elongated 

 leafy spike. Low Evening Primrose. 



4. ISNARDIA. Linn. Isnardia. 

 (In honor of Antotne d'Isnard ; a French botanist.) 



Tube of the calyx ovate or subcylindric, short, adhering to 

 the ovary ; limb 4-parted, persistent. Petals 4, often minute 

 or wanting. Stamens 4. Style filiform, deciduous. Stigma 

 capitate. Capsule short, 4-sided, 4-valved, many-seeded. 



* Petals 4. T.UDWIGIA. 



1 . /. alternifolia D. C. : stem erect, branched, nearly smooth ; leaves al- 

 ternate, lanceolate or oblong-lanceolate, somewhat scabrous on the margins 

 and under side ; peduncles axillary, 1-flowered ; lobes of the calyx large, 

 ovate, acuminate ; capsule obovoid-globose 4-cornered, the angles winged. 

 Ludwigia alternifolia Linn. Torr. fy Gr. L. macrocarpa Mich. 



Swamps. Can. to Flor. July. 1\..Stem 23 feet high, often purplish. 

 Flowers large, yellow, on short peduncles. Alternate-leaved Isnardia. 



2. I. uniflora. : stem straight, simple ; leaves alternate, lanceolate, acute, 

 smooth ; flower terminal j petals longer than the calyx. Ludwigia uni- 

 flora, Raf. 



Swamps. N. J. This seems to be sufficiently distinct. Dr. Torrey, how- 

 ever, suggests that it is a variety of the former. Single-flowered Isnardia. 



3. 7. hirtetta : hirsute ; stem erect, scarcely-angled ; leaves alternate, 

 ovate-oblong, sessile, upper ones narrower ; peduncles 1-flowered, axillary ; 

 capsule villous, globose, 4-angled, the angles slight winged. /. hirsuta 

 Pursh. Ludwigia hirtetta Raf. 



Ditches and pools. N. J. to Flor. July, Aug. 1|.. Stem 12 feet high, 

 simple or sparingly branched. Flowers bright yellow, axillary. 



Hairy Isnardia. 

 ** Petals very minute or none. ISNARDIA. 



4. /. sphfsrocarpa D. C. : stem erect, nearly smooth, much branched ; 

 leaves narrow-lanceolate, mostly acute, attenuate at base ; flowers solitary, 

 axillary, or clustered towards the summit of the branches ; capsule turbi- 

 nate-globose, obscurely 4-sided, canescent. Ludwigia sphterocarpa Ell. 



In water. Near Peekskill, N. Y. to Flor. July, Aug. Q.Stem about 2 

 feet high, reddish. Flowers in somewhat compound leafy spikes. Petals none. 



Round-fruited Isnardia. 



5. 7. palustris Linn. : stem prostrate, creeping, glabrous ; leaves opposite, 



