GENUS i. 



EVENING-PRIMROSE FAMILY. 



B. Fruit indehiscent, nut-like. 



Calyx-tube obconic ; filaments with scales at the base ; ovary 4-celled. 

 Calyx-tube filiform; filaments unappendaged ; ovary i -celled. 

 2. Floral whorls of 2 parts. 



1 8. Gaura. 



19. Stenosiphon. 



20. Circaea. 



I. 



ISNARDIA L. Sp. PI. 120. 1753. 



Annual or perennial succulent herbs. Stems prostrate or decumbent, creeping or float- 

 ing; leaves opposite, fleshy, narrowed into petioles which are slightly shorter than the blades. 

 Flowers perefect, axillary, sessile, commonly apetalous. Calyx turbinate, its segments 4, 

 shorter than the tube or slightly longer, persistent. Petals none, or 4, inconspicuous. Stamens 

 4; filaments very short; anthers ovoid or oblong. Ovary 4-celled, very short; styles often 

 almost wanting; stigma 4-lobed ; ovules numerous, in several rows. Capsule 4-angled, obovoid 

 or turbinate, straight, flat at the apex, septicidal. Seeds numerous, often transversely wrinkled. 

 [In honor of Antoine Dante Isnard, a French botanist, died I7 2 4-1 



About 4 species in Europe, North America, the West Indies and Mexico, the following typical. 



i. Isnardia palustris L. Marsh 

 Purslane. Fig. 3013. 



Isnardia palustris L. Sp. PI. 120. 1753. 

 Ludzvigia palustris Ell. Bot. S. C. i : 211. 1817. 



Procumbent or floating, glabrous, rooting 

 at the nodes, succulent. Stems branching, 

 4'-i5' long; leaves opposite, oval, ovate or 

 spatulate, acute or obtuse at the apex, 

 6"-i2" long, narrowed into slender peti- 

 oles ; flowers axillary, solitary, sessile, about 

 i" broad; bractlets at base of the calyx usu- 

 ally none ; calyx-lobes triangular, acute ; 

 petals small, reddish or often wanting; cap- 

 sule slightly longer than wide, about li" 

 high, somewhat exceeding the calyx lobes. 



In muddy ditches and swamps. Nova Scotia 

 to Manitoba and Oregon, Florida, Louisiana, 

 California and Mexico and the West Indies. 

 Widely distributed in the Old World. Also 

 called false or bastard loose-strife. Water- 

 purslane. Phthisic-weed. June-Nov. 



2. LUDWIGIANTHA Small, Bull. Torr. Club, 24: 178. 1897. 



Annual or perennial fleshy herbs. Stems prostrate, creeping, usually little branched ; 

 leaves opposite, sessile, numerous. Flowers axillary, solitary, perfect, yellow, on slender 

 bracted peduncles. Calyx narrowly obconic, its 4 segments narrow. Petals conspicuous, 

 surpassing the calyx-segments. Stamens 4 ; filaments elongated, very slender ; anthers ovoid. 

 Ovary 4-celled; united styles filiform, elongated; stigma 4-lobed; ovules numerous. Capsules 

 club-shaped, curved at the base at a right angle to the peduncle, about as long as the per- 

 sistent calyx, crowned by a 4-lobed stylopodium. [Derivation as in Ludwigia.] 



Two species of the southeastern United States, the first typical. 



Peduncles much longer than the leaves; calyx-lobes linear-lanceolate. i. L. arcuata. 



Peduncles shorter than the leaves ; calyx-lobes lanceolate. 2. L. brevipes. 



i. Ludwigiantha arcuata (Walt.) Small. 



Long-stalked Ludwigiantha. Fig. 3014. 

 Ludwigia arcuata Walt. Fl. Car. 89. 1788. 

 L. arcuata Small, Bull. Torr. Club 24: 178. 1897- 



Creeping or floating, rooting at the nodes, glabrous 

 or somewhat appressed-pubescent, little branched, 

 3'-i2' long. Leaves opposite, oblanceolate, sessile, 

 leathery, smooth, obtusish or acute at the apex, nar- 

 rowed at the base, 6"-i2" long; flowers 6"-io" broad 

 on filiform, 2-bracted peduncles much longer than 

 the leaves; calyx-lobes linear-lanceolate, acuminate, 

 shorter than the obovate petals; filaments and fili- 

 form style about 2" long ; capsule club-shaped, some- 

 what curved, glabrous, 4" -5" long, about equalling 

 the calyx-lobes. 



In swamps, Virginia to Florida. May-July. 



