ONAGRACEAE. 653 



rowed into slender petioles; flowers solitary, about 2 mm. broad; bractlets at base 

 of the calyx usually none; calyx-lobes triangular, acute; petals small, reddish, or 

 often wanting; capsule 4-sided, slightly Longer than wide, about 3 mm. high, 

 slightly exceeding the calyx lobes. In muddy ditches and swamps, N. S. to Man- 

 itoba, Ore., Fla., Cal. and Mex. Widely distributed in the Old World. June-Nov. 



2. LUDWIGIANTHA Small. 



Fleshy herbs. Stems prostrate, creeping; leaves opposite, sessile, numerous. 

 Flowers yellow, on slender bracted peduncles. Calyx-segments narrow, longer 

 than the tube. Petals conspicuous, surpassing the calyx-segments. Filaments 

 elongated. Ovary relatively long; united styles filiform, elongated. Capsule club- 

 shaped, curved at the base, about as long as the persistent calyx-segments. [Deriva- 

 tion as in the following genus.] A monotypic genus. 



I. Ludwigiantha arcuata (Walt.) Small. CURVED-PODDED LUDWIGIANTHA. 

 (I. F. f. 2556.) Stems glabrous or nearly so, 8-30 cm. long. Leaves oblanceolate, 

 leathery, smooth, obtusish at the apex, narrowed at the base, 12-25 mm - l n g; 

 flowers axillary, solitary, bright yellow, 8-12 mm. broad; calyx-lobes linear- 

 lanceolate, acuminate, shorter than the obovate petals; capsule club-shaped, some- 

 what curved, glabrous, 8-10 mm. long. In swamps, Va. to Fla. May-July. 



3. LUDwiGIA L. 



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

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

 lobes generally persistent. Petals usually 4. Stamens usually 4. Ovary 4-5- 

 celled. Capsule terete, ribbed or winged, septicidally 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 abun- 

 dant in N. Am. 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 cap- 

 sule separating 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; capsule top- 

 shaped, glabrous. 2. L. polycarpa. 

 Capsules cylindric or obpyramidal. 



Capsules cylindric. 3. L. glandulosa. 



Capsules obpyramidal. 



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



4. L. alata. 

 Capsules several times longer than broad, the angles obtuse. 



5. L. linearis. 

 Flowers showy, peduncled ; petals large, bright yellow ; capsules opening by an apical 



pore. 



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



Plants glabrous or nearly so ; capsules glabrous. 7. L. alternifolia. 



1. Ludwigia sphaerocarpa Ell. GLOBE-FRUITED LUDWIGIA. (I. F. f. 

 2557.) Stem generally finely pubescent, 6-9 dm. high, the lower part clothed 

 with serenchyma when growing in water. Leaves sessile, those of the stem and 

 branches lanceolate, acute at both ends, 5-10 cm. long, scabrous and minutely 

 denticulate, those of the stolons obovate; flowers sessile, greenish, about 3 mm. 

 broad; calyx-lobes triangular-ovate, acute; petals commonly none; capsule about 

 4 mm. high, scarcely longer than the calyx-lobes. In swamps, eastern Mass, and 

 southern N. Y. to Fla., west to La. July-Sept. 



2. Ludwigia polycarpa Short & Peter. MANY-FRUITED LUDWIGIA. (I. F. 

 f. 2558.) Stems glabrous, 3-9 dm. high. Leaves sessile, narrowly lanceolate, 

 acute at each end, 5-10 cm long, rough-margined, those of the stolons spatulate; 

 flowers sessile, about 3 mm. broad, greenish; calyx-lobes triangular-lanceolate, 

 acute, sometimes serrulate; petals minute, greenish; capsule glabrous, slightly 4- 

 sided, about 5 mm. high, often twice the length of the calyx- lobes. In swamps, 

 Ont. to Minn, and Mass., south to Ky., Neb. and Kans. July-Oct. 



