1955] 



REVISION OF THE GENUS SAGITTARIA 



189 



9. Filaments pubescent; leaves typically non-sagittate. Eastern North 

 America (no. 11 extending to South America). 

 10. Bracts more or less connate and membranous; filaments dilated or 

 subulate. 



11. Pistillate flowers subsessile or nearly so; scape geniculate at 

 the lowest whorl; achene-beak 0.8 mm or more long; filaments 

 subulate. 9. S. rigida. 



11. Pistillate flowers obviously stalked; scape erect; achene-beak 



shorter; filaments dilated. 10. S. graminea. 



10. Bracts thickened, papillose or ridged, nearly free; filaments linear. 



11. S. I and folia. 



9. Filaments glabrous; leaves typically sagittate (except nos. 12, 13 and 

 20). North-temperate (no. 14 Mexican, nos. 15 and 19 extending to 

 the tropics). 

 12. Plants of the New World. 



13. Bracts more or less papillose; leaves never sagittate. Southern 

 plains states. 



14. Bracts densely papillose, 7 mm or less long, obtuse; achenes 



1.5 mm or less long. Arkansas, Louisiana, Texas. 12. S. papulosa, 



14. Bracts sparsely papillose, longer, attenuate; achenes larger. 



Kansas, Missouri, Oklahoma. 13. S. ambigua. 



13. Bracts glabrous (if pubescent, the leaves sagittate); leaves typi- 

 cally sagittate. 



15. Pistillate pedicels greatly elongate, 5 cm or more long, at 



length recurved; flower-whorls remote (the internodes long), 

 Mexico. 14. S. macrophylla. 



15. Pistillate pedicels shorter, ascending; flower-whorls not remote. 

 16. Achene-beak laterally inserted. 



17. Bracts boat-shaped, obtuse or acute, more or less firm, 

 occasionally pubescent; beak 0.5 mm or more long. 

 Widespread. 15.5". lati folia. 



17. Bracts attenuate, more or less membranous, never pubes- 

 cent; beak shorter. Mexico, southern United States. 16. S. longiloba. 



16. Achene-beak apically insetred. 



18. Beak recurving, 0.5 mm or longer; achene-faces typically 



winged. Eastern United States. 17. S. engelmanniana. 



18. Beak erect, shorter; achene-faces plain or with resin-duct. 



Northern North America, Rocky Mountains. 18. S. cuneata* 



12. Plants of the Old World. 



19. Pistillate flowers on ascending pedicels; achenes entire-winged; 



beak erect. Eurasia. 19* S. sagitti folia. 



19. Pistillate flowers sessile; achenes toothed-winged; beak lateral. 



Asia. 20. S. pygmaea. 



Subgenus 1. Lophotocarpus (T. Dur.) Bogin, comb. nov. 



Sagittaria sect. Lophiocarpus* Kunth, Enum. PI. 3: 161. 1841. 

 Lopbiocarpus Miq. 111. Fl. Arch. Ind. 50. 1870. Non Lophiocarpus Turcz. 

 Lophotocarpus T. Dur. Ind. Gen. Phan. x. 1888. 

 Michelia T. Dur. Ind. Gen. Phan. 504. 1886. Non Michelia L. 



Mature pistillate flowers with appressed to spreading sepals, their pedicels 

 recurved, more or less thickened. Perfect flowers occasionally present. (Species 

 1-8.) 



Type species: Sagittaria guyanensis H.B.K. Nov. Gen. & Sp. 1: 250. 1815. 



Distribution: Tropical and warm- temperate. Completely New World except for 

 one pantropical species (S. guyanensis). A portion of another species is south- 

 temperate in distribution (5. montevidensis)\ all the remainder are tropical or 

 warm north-temperate. 



Type species: Sagittaria sagitti folia L. (which is also the type of the genus). 



Distribution: Essentially north-temperate New World. Two species, S. sagitti- 

 folia and 5. pygmaea, are Old World, with the former extending into the tropics. 



