177 



I think Linnaeus' idea of holding Isnardia palustris genetically 

 separate from Ludzvigia altemifolia is the proper way of disposing 

 of these widely divergent species and their respective relatives. 

 There are three clear generic lines in Liidwigia as it is limited 

 by most authors and I think it is much more satisfactory to treat 

 these groups as separate genera than to associate them as sub- 

 genera in a composite genus. 



I append a synopsis which will serve to emphasize the diag- 

 nostic characters : 



Leaves opposite ; stems prostrate or decumbent, creeping or floating. 



Flowers sessile ; petals wanting or very small ; leaves petioled ; capsules short, 



sessile, straight, with a flat or depressed top. I. Isnardia. 



Flowers long-stalked ; petals large and conspicuous ; leaves sessile ; capsules 

 elongated, long-stalked, curved, with a prominent 4-lobed stylopodium. 



2. Ludwigantha. 

 Leaves alternate ; stems erect or ascending. 3. Ludwigia. 



I. ISNARDIA L. Sp. PI. 120. 1753. 



Key to the Species- 

 Petals usually none ; capsules 2.5-4 mm. long. 



Pubescent; capsules 2.5-3 mm. long. I. !• spathulata. 



Glabrous ; capsules 3-4 mm. long. 2. /. palutris. 



Petals usually present ; capsules 6-7 mm. long. 3. /• natans. 



I. Isnardia spathulata (T. & G.). 



Ludzvigia spathulata T. & G. Fl. N. A. i : 526. 1840. 

 Around pine barren ponds, middle Florida. 



2. Isnardia palustris L. Sp. PI. 120. i753- 



Ludzvigia apctala Walt. Fl. Car. 89. 1788. 

 Ludzvigia nitida Michx. Fl. Bor. Am. i: 57. 1803. 

 Ludwigia palustris Ell. Bot. S.C. & Ga. i: 211. 1817. 

 Lsnardia palustris var. Americana DC. Prodr. 3: 61. 1828. 

 Lsnardia ascendens Hall; Eaton & Wr. N. A. Bot. 285. 1840. 

 Ditches,streams and ponds, throughout eastern North America. 



3. Isnardia natans (Ell.). 



Ludzvigia natans Ell. Bot. S. C. & Ga, i: 518. 18 17. 

 Streams and marshes, North Carolina to Florida and Mexico. 



