ludwigia. OXAGRACEiE. 221 



= = Stigina entire or rarely 4-toothed : ovaries and capsule sessile 

 or nearly so. 



7. Taraxia. Stigma capitate: calyx-tube longer than the ovary, usually 

 adherent to the style. 



8. Sphserostigina. Stigma capitate: calyx-tube campanulate, shorter 

 than the ovary. 



= = = .Stigma capitate, ovules and capsule long-stalked. 



9. Chylismia. Calyx-tube somewhat funnel-form, many times shorter 

 than the ovary. 



*+ *+ Flowers irregular : the alternate stamens longer. 



10. Pachylophus. Plants normally acaulescent: ovules and seeds few, 

 sessile : seeds with a deep furrow along the raphe. 



+- -*- Anthers attached at or near the base, remaining erect; those 

 opposite the petals much shorter or sterile, rarely wanting ; petals 

 never yellow. 



11. Godetia. Calyx-tube above the ovary obconical, its lobes reflexed. 

 Petals sessile, entire, rarely 2-lobed. Capsule coriaceous. Seeds nu- 

 merous angled or margined. 



12. Boisduvalia. Calyx-tube above the ovary obconical, its lobes erect. 

 Petals sessile, 2-lobed. Capsule membranaceous, the cells few-seeded, 

 seeds smooth. 



13. Clarkia. Calyx-tube above the ovary obconical; its lobes reflexed. 

 f'etals with claws either lobed or entire: the stamens opposite them 

 often sterile. Capsule coriaceous. 



Tribe III. Gaurixe.e. Limb or produced tube of the calyx 

 deciduous lrom the dry and indehiscent 1-4-seeded fruit. Parts 

 of the flowers in 4's or rarely H's. Leaves alternate. 



14. Gaura. Stamens 8, all perfect. Anthers attached by the middle, 

 versatile. 



15. Heterogaura. Fertile stamens 4 with anthers attached at the base, 

 sterile stamens 4 opposite the petals. 



Tribe IV. Circee.e. Limb of the calyx deciduous from the 

 indehiscent burr-like 1-2-seeded fruit. Parts of the flowers in 

 2's throughout. Leaves opposite. 



16. Circaea. Small perennial herbs with opposite petioled leaves. 



LTJDWIGIA L. Gen. n. 153. 



Calyx-tube not produced beyond the short ovary, the 4 lobes 

 usually persistent. Petals 4 often small or wanting. Stamens 

 4 ; filaments bhort. Capsule short or cylindrical, many-seeded, 

 4-valved, dehiscent septicidally or by openings at the summit. 

 Seeds minute. Aquatic or marsh perennials; leaves entire (op- 

 posite in one species) ; flowers axillary, mostly solitary and 

 sessile. 



L. palustris Ell. i, 211. Stems creeping and rooting in the mud or 

 floating, 4-12 inches long or more: leaves all opposite, ovate or oval, 6-12 

 lines long tapering to a short petiole acute : flowers solitary, sessile : petals 

 none or short ana reddish : capsule short-oblong 2 lines long or less some- 



