Voi,. II. ] 



EVENING-PRIMROSE FAMILY. 



477 



at the base at a right angle to the peduncle, about as long as the persistent calyx-segments, 

 crowned by a prominent 4-lobed stylopodium. [Derivation as in the following genus.] 

 A monotypic genus of the southeastern United States. 



i. Ludwigiantha arcuata (Walt.) Small. 

 Curved-podded Ludwigiantha. (Fig. 2556.) 



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

 Ludwigiantha arcuata Small, Bull. Torr. Club, 24: 



178. 1897. 



Creeping or floating, rooting at the nodes, gla- 

 brous or nearly so, little branched, tf-i.'i' long. 

 Leaves opposite, oblanceolate, sessile, leathery, 

 smooth, obtusish at the apex, narrowed at the 

 base, 6 // -i2 // long; flowers axillary, solitary, bright 

 yellow, 4 // -6 // broad on filiform, 2-bracted pedun- 

 cles much longer than the leaves ; calyx-lobes 

 linear-lanceolate, acuminate, shorter than the 

 obovate petals; capsule club-shaped, somewhat 

 curved, glabrous, about 4 // -5 // long, equalling or 

 slightly longer than the calyx-lobes. 



In swamps, Virginia to Florida. May-July. 



3. LUDWIGIA L. Sp. PI. 118. 1753. 



Perennial or annual herbs, with alternate usually entire leaves, and axillary or terminal, 

 yellow or greenish flowers. Stems erect or ascending, sometimes angled, or winged. Calyx- 

 tube cylindric, obpyramidal or top-shaped, not prolonged beyond the ovary, 3-5-lobed 

 (usually 4-lobed), the lobes generally persistent. Petals usually 4 sometimes none, inserted 

 under the margin of the disk. Stamens usually 4, inserted with the petals; filaments short. 

 Ovary 4~5-celled; stigma capitate or 4-lobed. Capsule terete, ribbed or winged, crowned 

 with the calyx-lobes, many-seeded, septicidally or irregularly dehiscent, or opening by an 

 apical pore. [Named in honor of C. G. Ludwig, 1709-1773, Professor of Botany at Leipsic.] 

 About 25 species, natives of warm and temperate regions, most abundant in North America. 

 Besides the following about 10 others occur in the southern and southwestern States. 

 Flowers inconspicuous; petals none, or small, yellowish or greenish; valves of the capsule separat- 

 ing from the terminal disk. 

 Capsules subglobose or top-shaped. 



Bractlets at the base of the calyx minute, or none; capsule subglobose, finely pubescent. 



i. L. sphaerocarpa. 

 Bractlets at the base of the calyx linear, about equalling the capsule 



glabrous. 



Capsules cylindric or obpyramidal. 

 Capsules cylindric. 

 Capsules obpyramidal. 



Capsules as long as broad, or broader, the angles winged. 

 Capsules several times longer than broad, the angles obtuse. 



Flowers showy, peduncled; petals large, bright yellow; capsules opening by atT apical pore. 

 Plants hirsute ; capsules bristly pubescent. 6. L. hirtella. 



Plants glabrous; capsules glabrous. 7. L. alternifolia. 



i. Ludwigia sphaerocarpa Ell. Globe- 

 fruited Ludwigia. (Fig. 2557.) 



capsule top-shaped, 



2. L. polycarpa. 



3. L. glandulosa. 



4. L. alata. 



5. L. linearis. 



Ludwigia rudis Walt. Fl. Car. 89. 1788. ? 

 Ludivigia sphaerocarpa Ell. Bot. S. C. i: 213. 



1817. 



Erect, branching, generally finely pubescent, 

 stoloniferous, 2-3 high, the lower part of the 

 stem clothed with aerenchyma when growing in 

 water. Leaves alternate, sessile, those of the stem 

 and branches lanceolate, acute at both ends, 2 / -4 / 

 long, scabrous and minutely denticulate, those 

 of the stolons obovate; flowers solitary, sessile, 

 greenish, about i%" broad; bractletsat base of 

 calyx minute or none; calyx-lobes triangular- 

 ovate, acute; petals commonly none; capsule 

 subglobose, about 2" high, scarcely longer than 

 the calyx- lobes, finely pubescent. 



In swamps, eastern Massachusetts and southern 

 New York to Florida, west to Louisiana. July-Sept. 



