176 ONAGRACE^E. (EVENING-PRIMROSE FAMILY.) 



nut-like, 1-celled, 1-seeded. — Perennial aquatics, with simple entire leaves in 

 whorls, and minute flowers sessile in the axils in summer. (Name from liriros, 

 a horse, and ovpd, a tail. ) 



1. H. vulgaris, L. Leaves in whorls of 8 or 12, linear, acute. — Ponds 

 and springs, New York to Kentucky and northward : rare. Stems simple, 1°~ 

 2° high. Flowers very inconspicuous. (Eu.) 



Order 39. ONAGBACEJB. (Evening-Primrose Family.) 



Herbs, with 4-merous {sometimes 2-3- or 5 - 6-merous) perfect and sym- 

 metrical Jlowers ; the tube of the calyx cohering with the 2-4-celled ovary, 

 its lobes valvale in the bud, or obsolete; the petals convolute in the bud, some- 

 times wanting ; and the stamens as many or twice as many as the petals or 

 calyx-lobes, inserted on the summit of the calyx-tube. Style single, slen- 

 der : stigma 2 - 4-lobed or capitate. Pollen grains olten connected by cob- 

 webby threads. Seeds anatropous, small, without albumen. 



* Parts of the flower in twos. 



1. Circeea. Petals 2, obcordate or 2-lobed. Stamens 2. Fruit 1 - 2-seeded, bristly. 



# * Parts of the flowers in fours or more, 

 -t- Fruit dry and indehiscent, mostly becoming 1-celled, 1-4-seeded. 



2. Gaura* Petals 4 Stamens 8 and with the long style turned downwards. 



h- ■*- Fruit a many -seeded pod, usually loculicidal. 



3. Epilobium, Stamens 8 Petals 4. Seeds with a large downy tuft at the apex. 



4. Oenothera. Stamens 8 and petals 4 on the prolonged calyx-tube. Seeds naked. 



5. Jussisea. Stamens 8-12. Petals 4-6. Calyx-tube not prulonged beyond the ovary. 



6. Ludwigia. Stamens 4. Petals 4 or more. Calyx-tube not prolonged beyond the ovary. 



1. CIRC iE A, Tourn. Enchanter's Nightshade. 



Calyx-tube slightly prolonged, the end filled by a cup-shaped disk, deciduous ; 

 lobes 2, reflexed. Petals 2, inversely heart-shaped. Stamens 2. Fruit inde- 

 hiscent, small and bur-like, bristly with hooked hairs, 1-2-celled: cells 1-seeded. 

 — Low and inconspicuous perennials, in cool or damp woods, with opposite thin 

 leaves on slender petioles, and small whitish flowers in racemes, produced in 

 summer. (Named from Circe, the enchantress.) 



1. C. Lutetiana, L. Taller (l°-2° high) ; leaves ovate, slightly toothed; 

 bracts none; hairs of the roundish 2-cdled fruit bristly. — Very common. JEu.) 



2. C. alpina, L. Low (3' -8' high), smooth and weak; leaves heart-shaped, 

 thin, shining, coarsely toothed; bracts minute; hairs of the obovate-oblong \-ceiled 

 fruit soft and slender. — Deep woods . common northward. July. (Eu.) 



2. GAURA, L. Gaura. 



Calyx- tube much prolonged beyond the ovary, deciduous ; the lobes 4 (rarely 

 3), reflexed. Petals clawed, unequal or turned to the upper side. Stamens 

 mostly 8, often turned down, as is also the long style. A small scale-like ap- 

 pendage before the base of each filament. Stigma 4-lobed, surrounded by a 

 ring or cup-like border. Fruit hard and nut-like, 3 - 4-ribbed or angled, inde- 



