594 ONAGRACEAE (EVENING PRIMROSE FAMILY) 



ONAGRACEAE (Evening Primrose Family) 



Herbs, tmth ^-merous (sometimes 2-3- or o-O-merous) perfect and symmetrical 

 flowers; the tube of the calyx adhering to the 2-4-ceUed ovary, its lobes valvate 

 in the bud or obsolete; the petals convolute in the bud, sometimes 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, slender ; stigma 2-4-lobed or capi- 

 tate. Pollen-grains often connected by cobwebby threads. Seeds anatropous, 

 small, without albumen. — Mostly herbs, with opposite or alternate leaves. Stip- 

 ules none or glandular. 



♦ Parts of the flower in fours or more numerous. 

 ■»- Fruit a many-seeded pod, usually loculicidal. 



++ Calyx-limb (divided to the summit of the ovary) persistent. 



1. Jussiaea. Petals 4-6. Stamens twice as many. Capsule elongated, 4-6-celled. 



2. Ludvigia. Petals 4 or none. Stamens 4. Capsule short. 



«• ++ Calyx-tube or deeply cleft limb deciduous from the summit of the capsule ; petals 4 ; 



stamens 8. 

 8. Epilobium. Seeds silky-tufted. Flowers (in ours) not yellow. Lower leaves often opposite. 



4. Oenothera. Seeds not tufted. Flowers mostly yellow. Leaves alternate. 



•«- +- Fruit dry and indehiscent, 1-4-seeded. 

 ++ Terrestrial ; leaves alternate ; stamens 6-8. 



5. Gaura. Calj-x-tube obconical. Filaments appendaged at base. 



6. Stenosiphon. Calyx-tube filiform. Filaments (8) not appendaged. 



++ ++ Aquatic ; leaves opposite or whorled ; stamens 4. 



7. Trapa. Calyx-tube short. Filaments unappendaged. Fruit large, coriaceous, turbinate. 



* * Parts of the flower in twos ; leaves opposite. 



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



1. JUSSIAEA L. Primrose-willow 



Calyx-tube elongated, not at all prolonged beyond the ovary ; the lobes 4-6^ 

 herbaceous and persistent. — Herbs (ours glabrous perennials), with mostly 

 entire and alternate leaves, and axillary yellow flowers in summer. (Dedicated 

 to Bernard de Jussieu^ the founder of the Natural System of Botany.) 



1. J. decurrens (Walt.) DC. Stem erects 3-6 dm. high, winged by the decur- 

 rent lanceolate leaves ; calyx-lobes 4, as long as the petals ; capsule cylindric- 

 club-shaped, wing-angled ; seeds in several rows in each cell. — Wet places, 

 •* Md." and Va. to Fla.; s. HI. and Mo. to La. and Tex. 



2. J. diffusa Forsk. Stem creeping, or floating and rooting ; leaves oblong, 

 tapenng int^ a slender petiole ; flowers large, long-peduncled ; calyx-lobes and 

 obovate petals 5; pod woody, cylindrical, with a tapering base ; seeds quadrate, 

 in 1 row in each cell, adherent to the spongy endorarp. (J. repens of auth., 

 probably not of L.) — In water or on muddy banks, Ky. and 111. to e. Kan., and 

 southw. 



2. LtJDViGIA L. False Loosestrife 



Calyx-tube not at all prolonged beyond the ovary ; the lobes 4, usually per- 

 sistent. Capsule short or cylindrical, many-seeded. — Perennial herbs, with 

 axillary (rarely capitate) flowers through summer and autumn. (Named lor 

 C G. Ludwig, Professor of Botany at Leipsic, contemoorary with Linnaeus.) 



