1955] 



REVISION OF THE GENUS SAGITTARIA 



193 



Sagittaria cordifolia Roxb. Fl. Ind. 3: 647. 1832. 



Sagittaria nymphaei folia Hochst. ex Steud. Nom. ed. 2. 2: 491. 1840. Nomen nudum. 

 Sagittaria blumei Kunth, Enum, PI. 3: 158. 1841. 

 Sagittaria obtusissima Hassk. Cat. PI. Hort. Bog. 26. 1844, 

 Lophiocarpus cordifolius (Roxb.) Miq. 111. Fl. Arch. Ind. 2: 50. 1870. 

 Lophiocarpus lappula (D. Don) Miq. 111. Fl. Arch. Ind. 2: 50, 1870. 



Lophiocarpus cordifolius var. madagascariensis Buch. Abh. Nat. Ver. Brem. 7: 30. 

 1880. 



Sagittaria parviflora Wall, ex Micheli in DC. Monogr. Phan. 3: 62. 1881. Nomen nudum. 

 Lopbotocarpus guyanensis var. lappula (D. Don) Buch. Pflanzenreich 4(15): 36. 1903. 

 Lophotocarpus guyanensis var. madagascariensis Buch. Pflanzenreich 4(15): 36. 1903. 

 Lopbotocarpus formosanus Hayata, Ic. PI. Formos. 5: 249. 1915. 



Achenes compressed, 2.5-3.5 x 1.8-3 mm, the wings typically deeply crested, 

 rarely nearly smooth, their faces usually prominently 1-ribbed, the rib occasionally 

 remotely echinate, rarely unadorned. (FIG. 5c.) 



Type collection: Hamilton s.n., Nepal (holotype thought to be at Edinburgh, 

 not found). 



Distribution: Old World tropics, absent in Australia and Oceania. Collections 

 examined from Africa: Anglo-Egyptian Sudan, Madagascar, Nigeria; from Asia: 

 Burma, China, Formosa, Hong Kong, India, Indo-China, Java, Malaya, Pakistan, 

 Siam. It has also been reported in the other East Indian Islands associated with 

 the Asiatic flora. It is, however, absent from the Philippines and Ceylon. (Fig. 5.) 



A widespread, pantropical species of lakes, swamps, and the nearly stagnant 

 waters of streams. The most common Sagittaria of the tropics, with cordate leaf- 

 blades always floating, never emersed. The flowers are produced under water, but 

 typically are found floating at or near the surface. 



The remarkable and almost unique pantropical distribution may be correlated 

 with the obviously primitive features of the species. In floral structure, it is nearly 

 intermediate between Sagittaria and Echinodorus. The pistillate flowers regularly 

 bear a ring of 6-9 functional stamens and the staminate flowers usually show 

 remnants of aborted pistils. Many authors have based the maintenance of this 

 species in the separate genus Lopbotocarpus on these characteristics. The re- 

 curved, thickened pedicels and the appressed sepals of the mature pistillate 

 flowers show the close relationship of Sagittaria guyanensis with S. montevidensis 

 and S. rhombifolia. Its achenes and leaf-shape are quite distinctive. 



As a member of a genus whose species are characterized by wide variation in 

 leaf-shape, 5. guyanensis is, oddly enough, extremely constant in leaf-form. This 

 constancy is even more remarkable in the light of its wide distribution. Vegeta- 

 tively and rlorally, there is absolutely no basis for separating this taxon into 

 different species. The present treatment, with division into two subspecies, is 

 justified on the basis of achene characteristics and correlated geographical dis- 

 tribution. The Old World plant is characterized by a uniformly larger achene, 

 flattened in cross section, with deeply crested wings and relatively little facial 

 adornment (5. lappula D. Don). It must be noted, however, that in some Madagascan 

 plants the achene is reduced in size and the cresting nearly absent (var. mada- 

 gascariensis Buch.). The New World subspecies has an achene plump in cross 

 section, uniformly smaller in size, with the wings typically shallowly crested and 

 the faces markedly echinate (5. echinocarpa Mart.). Some northern South American 

 plants have achenes without facial adornment (var. typicus Buch.), a trend result- 

 ing finally in a completely unadorned achene without even wing-cresting (S. seuber- 

 tiana Mart.). The extensive synonymy has resulted from the wide geographical 

 range, the confusion in deciding on generic characteristics, and the variation 

 in the achenes. 



