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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 4 [Vol. 9, No. 2 



4d. Sagittaria mbntevidensis subsp. spongiosa (Engelm.) Bogin, comb. nov. 

 Sagittaria calycina var. spongiosa Engelm. in Gray, Man. Bot. ed. 5, 493. 1867. 

 Lopbotocarpus spongiosus (Engelm.) J.G.Sm. Missouri Bot. Gard. Rep. 11: 148. 1899. 

 Lop botocarpus spatulatus J.G.Sm. Missouri Bot. Gard. Rep. 11: 149. 1899. 

 Sagittaria spathulata (J.G.Sm.) Buch. Pflanzenreich 4(15): 40. 1903. 



Annual. Plants submerged at high tide, emersed or stranded at low tide. The 

 rare, permanently emersed leaves sagittate, the typical leaves modified into 

 lanceolate phyllodia 4-18 x 0.6-1.1 cm, the free ends often spatulate to 1.5 cm 

 wide. Scape simple, typically reduced to 2-3 whorls of flowers. Bracts connate, 

 to 0.5 cm long, occasionally reduced or absent. Pistillate flowers with thickened 

 recurved pedicels 1-3 cm long; sepals 0.3-0.5 x 0.4-0.6 cm, scarcely covering a 

 third of the receptacle at maturity; functional stamens usually present. Staminate 

 flowers often absent. Stamens ca. 12, with glabrous, linear filaments 0.8-1.3 mm 

 long. Mature pistillate receptacle 0.6-1 cm in diameter; achenes 1.5-2 x 0.8-1.1 

 mm, the resin duct typically present, the beak often laterally inserted with the 

 free end depressed. (FIG. 8 c.) 



Type collection: Tatnall s.rc., July I860, Wilmington, Delaware (holotype MO, 

 isotype GH). The type collection includes plants approaching subsp. calycina as 

 well as the more typical tidal forms. 



Distribution: Brackish to nearly fresh tidal waters and salt marshes, Potomac 

 River north to the Gaspe. Collections examined from Quebec and New Brunswick 

 in Canada and from Connecticut, Delaware, Maine, Maryland, Massachusetts, 

 New Hampshire, New Jersey, New York, Virginia in the United States. (FIG. 8.) 



A wide ranging New World species, typically warm-temperate in distribution, 

 but present in both tropical and cold-temperate latitudes. S. montevidensis is 

 most closely related to the primitive species of the subgenus Lopbotocarpus (S. 

 guyanensis, 5. rhombifolia, 5. sprucei), sharing with them the closely appressed 

 sepals of the mature pistillate flower. The more advanced members of the sub- 

 genus, characterized by the spreading sepals and the semitropical and warm- 

 temperate North American distribution, are apparently derived without exception 

 from S. montevidensis. The reduction of S. chilensis, 5". calycina, and S. spongiosa 

 to subspecies of S. montevidensis is based on the similarity of the mature achenes 

 and the presence of numerous specimens exhibiting intermediate characteristics. 

 The only workable method of segregating the various subspecies is on the basis 

 of geographical distribution and a few correlated differences that seem more or 

 less constant. The description of each subspecies has intentionally been limited 

 to the typical plants of each; at the same time intermediate plants have been 

 included in each group that can be reliably identified only on their geographic 

 origin. The apparently complete isolation of each subspecies precludes hybridi- 

 zation as a cause for these intermediates and suggests that each group is very 

 closely allied. 



The two wide-ranging subspecies, montevidensis of South America and calycina 

 of North America, are completely isolated from each other and yet are only ten- 

 uously separated on the basis of the presence or absence of a purple spot at the 

 base of the petals, of functional stamens in the pistillate flowers, and of the very 

 plastic characteristic of bract-length. The localized South American subspecies 

 chilensis , with widely divergent lobes of the sagittate leaves, enormously en- 

 larged pistillate pedicels and glabrous, dilated filaments, in its typical form 

 differs distinctly from subsp. montevidensis; however, all shades of intergradation 

 of characteristics are present within its range. The same situation holds true for 

 the localized subspecies spongiosa of North America and subspecies calycina. 

 The former is a tidal plant of the Atlantic coast, while the latter ranges inland 



