177 
I think Linnaeus’ idea of holding /snardia palustris generically 
separate from Ludwigia alternifolia is the proper way of disposing 
of these widely divergent species and their respective relatives. 
There are three clear generic lines in Ludwigia 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. 1. Jsnardia, 
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. 
1. ISNARDIA L. Sp. Pl. 120. 1753. 
Key to the Species. 
Petals usually none; capsules 2.5—4 mm. long. 
Pubescent; capsules 2.5-3 mm. long. 1. J. spathulata, 
Glabrous ; capsules 3-4 mm. Jong. 2. L, palutris. 
Petals usually present; capsules 6-7 mm. long. 3. J. natans. 
1. ISNARDIA SPATHULATA (T. & G.). 
Ludwigia spathulata T. & G. FI. N. A. 1: 526. 1840. 
Around pine barren ponds, middle Florida. 
2. IsSNARDIA PALUSTRIS L. Sp. Pl. 120. 1753. 
Ludwigia apetala Walt. Fl. Car. 89. 1788. 
' Ludwigia nitida Michx. F1|. Bor. Am. 1:57. 1803. 
Ludwigia palustris Ell. Bot. S.C. & Ga. 1: 211. 1817. 
Isnardia palustris var. Americana DC. Prodr. 3: 61. 1828. 
Isnardia ascendens Hall; Eaton & Wr. N. A. Bot. 285. 1840. 
Ditches, streams and ponds, throughout eastern North America. 
3. IsNARDIA NATANS (EIl.). 
Ludwigia natans Ell. Bot. S. C. & Ga. 1: 518. 1817. 
Streams and marshes, North Carolina to lie and Mexico. 
