1955] 



REVISION OF THE GENUS SAGITTARIA 



229 



Sagitta aquatica (S. F. Gray) St. Lager in Cariot Etudes Fl. ed. 8. 2: 819. 1899. 



Sagitta palustris Bub. Fl. Pyren. 4: 4. 1891. 



Sagittaria aginashi Makino, Bot. Mag. Tok. 15: 104. 1901. 



Sagittaria hyp erborea Laest. ex. Lindb. Medd. Soc. Faun. Fl. Fenn. 27: 66. 1901. 

 Nomen nudum. 



Sagittaria septentrionalis Laest. ex. Lindb. Medd. Soc. Faun. Fl. Fenn. 27: 66. 1901. 

 Nomen nudum. 



Sagittaria leucopetala (Miq.) Bergm. Vasti PI. Rot. 479. 1924. 

 Sagittaria tri flora Auct. non L. 



Perennial with runners and corms, rarely with rhizomes. Leaves emersed, 

 floating, or submerged, the emersed sagittate leaves with linear to ovate deltoid 

 blades 3-16 x 0.3-7 cm, the linear to lanceolate deltoid basal lobes 2-20 x 0.2-4 

 cm, the floating leaves linear to oblong, rarely cordate, the submerged modified 

 into linear flattened phyllodia to 30 cm long or longer, the petioles 10-100 cm 

 long. Scape 10-100 cm long, with 2-10 whorls of flowers, occasionally branching 

 at the lowest whorl. Bracts free or joined at the base, more or less firm, lanceo- 

 late, 0.3-1.5 cm long. Pistillate pedicels ascending 0.5-1.5 cm long, occasionally 

 nearly sessile, those of the staminate flowers typically longer and somewhat 

 thinner. Sepals reflexed, 0.4-0.7 cm long. Petals white, typically with base purple- 

 spotted, ca. twice the length of the sepals. Stamens numerous, the glabrous, 

 linear filaments 1-2 mm long, usually exceeding the linear to ovate anthers. Mature 

 receptacle 1-2 cm in diameter; achenes obovate to nearly orbicular, 2.5-4.5 x 

 1.6-3.5 mm, the broad dorsal wing to 1.3 mm wide, ca. twice as wide as the ven- 

 tral wing, the faces unadorned or with a single resin duct, the apical erect beak 

 0.2-0.8 mm long. (FIG. 3a-c.) 



Type locality: Europe. A number of collections from Europe and Asia, annoted 

 by Linnaeus, are present in the herbarium of the Linnean Society. 



Distribution: Europe and Asia, absent only in the more arid regions. S. sagitti- 

 folia grows in a wide range of aquatic habitats from the subarctic to the tropics. 

 This Sagittaria is the common species of the Old World and the only member of 

 the genus throughout a great part of its range. Collections examined from Austria, 

 Belgium, Denmark, England, Finland, Germany, Hungary, Ireland, Italy, Nether- 

 lands, Norway, Russia, Sweden, and Switzerland in Europe and from Assam, 

 Afghanistan, Burma, China, Formosa, India, Indochina, Indonesia, Japan, Korea, 

 Manchuria, Mongolia, Pakistan, Philippines, Ryukyu Islands, Siam, and Siberia in 

 Asia. (FIG. 3.) 



The glabrous filaments and sagittate emersed leaves show the close relation- 

 ship between 5. sagittifolia and the S. latifolia group of the New World. It is also 

 closely related to the only other Old World species of the subgenus, S. pygmaea. 



An extremely variable species vegetatively, S. sagittifolia responds to tem- 

 perature and water-level changes in much the same manner as S. cuneata. The 

 entire subarctic and alpine portion of the species, with almost exclusively float- 

 ing or submerged leaves and generally smaller achenes, has regularly been sepa- 

 rated as S. natans Pallas. After close study of the available material and after 

 critically comparing it to the very similar New World 5. cuneata, the present writer 

 can find no basis for maintaining S. natans on any taxonomic level. The only other 

 taxon presently maintained by authors, but here included in synonymy, is var. 

 leucopetala. This is a warm-temperate or tropical segregate from East Asia with 

 all-white petals but certainly no other distinguishing characteristics. The balance 

 of the numerous proposed taxa, resulting from the vegetative variability and the 

 wide distribution, have previously been reduced to synonymy by other students of 

 the genus. 



