2(1). Petals absent; capsule with a broad green band at each comer 



12. L. palustris. 



2. Petals present; capsule lacking green bands 13. L. repens. 



3(1 ). Stamens twice as many as the sepals, in 2 series (4) 



3. Stamens as many as the sepals, in 1 series (8) 



4(3). Stems conspicuously 4-winged 1. L. decurrens. 



4. Stems not conspicuously 4-winged (5) 



5(4). Sepals 4; seeds in several series in each locule of the capsule, free 



2. L. octovalvis. 



5. Sepals 5 (rarely 6); seeds in 1 series in each locule of the capsule, sur- 



rounded by woody endocarp at maturity (6) 



6(5). Seeds each surrounded by a horseshoe-shaped (hippocrepiform) piece 

 of endocarp, readily faUing free 3. L. leptocarpa. 



6. Seeds fused in large masses of endocarp, the entire capsule tough and woody 



(7) 



7(6). Flowering stems erect; plants covered with long spreading pubescence; 

 petals 12-33 mm. long 5. L. Uruguay ensis. 



7. Flowering stems usually decumbent; plants subglabrous; petals 7-14 (-24) 



mm. long 4. L. peploides. 



8(3). Capsule nearly globose, opening by a terminal pore; roots fascicled; stolons 

 lacking (9) 



8. Capsules variable in shape, irregularly dehiscent; roots not fascicled or if so 



the capsule not globose; plants with creeping stolons (10) 



9(8). Plants hirsute; leaves sessile 6. L. hirtella. 



9. Plants glabrous to puberulent; leaves petiolate 7. L. alternifolia. 



10(8). Petals present 8. L. linearis. 



10. Petals absent (11) 



11(10). Plants glabrous to pubescent or strigulose; bracteoles less than 2 mm. 

 long or wanting (12) 



11. Plants conspicuously pilose; bracteoles inserted above the base of the capsule, 



2.5-4.2 mm. long 9. L. pilosa. 



12(11). Capsule globose to subglobose. 2.5-5.6 mm. long 10. L. sphaerocarpa. 



12. Capsule subcylindric, 2-8 mm. long, 1.5-2 mm. thick 11. L. glandulosa. 



1. Ludwigia decurrens Walt. Primrose-willow. Fig. 551. 



Subglabrous erect herb to 2 m. tall, freely branched, the stems 4-winged; leaves 

 lanceolate to elliptical, 2-12 (-16) cm. long, 2-35 mm. wide, subsessile; sepals 4, 

 7-10 mm. long; petals 8-12 mm. long; stamens 8; disk not elevated, with a sunken 

 white-hairy nectary surrounding the base of each epipetalous stamen; capsule 1-2 

 cm. long, 3-4.5 mm. thick, sharply 4-angled, irregularly and readily loculicidal, 

 the pedicel 0-1 cm. long; seeds in several series in each locule, free, 0.3-0.4 mm. 

 long, the raphe about one fifth the diameter of the body. Jussiaea decurrens 

 (Walt.) DC. 



Swamps and wet places, in water of ditches and streams, about ponds and often 

 forming a vegetative mat in lakes, in Okla. (McCurtain, Mcintosh, LeFlore, 

 Johnston, Adair, Sequoyah and Choctaw cos.) and e. Tex., June-Oct.; s.e. U.S. to 

 e. Tex. and scattered to n. Arg. 



2. Ludwigia octovalvis (Jacq.) Raven subsp. octovalvis. Fig. 552. 



Subglabrous to strigulose usually well-branched weedy herb to 1 m. tall or more; 

 leaves lanceolate or narrowly lanceolate to narrowly ovate, 3-14.5 cm. long, 4-40 



1178 



