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



simple with 3-10 whorls of flowers, rarely branching at the lowest whorl. Bracts 

 linear, 1-3 cm long, remotely papillose, scarcely joined at the base, the free 

 ends often recurving. Pedicels ascending, 1-2.5 cm long. Sepals 0.5-0.7 cm long, 

 reflexed, remotely papillose. Petals white, less than twice as long as the sepals. 

 Stamens 15-21, the linear glabrous filaments 1-1.5 mm long, equaling or somewhat 

 exceeding the subglobose anthers. Mature receptacle 0.8-1.2 cm in diameter; 

 achenes oblong, 1.8-2.1 x 1.3-1.5 mm, narrowly winged, the faces 1-winged, the 

 laterally inserted minute beak to 0.15 mm. (FIG. 12d-f.) 



Type collection: 1875, G. D. Butler s.n., 'Indian Territory' probably Oklahoma 

 (lectotype MO). Smith did not designate a type in his original description of 5*. 

 ambigua. He did cite a number of collections however, most of which are now 

 missing from the herbaria in which he worked. The selected lectotype was cited 

 and annotated by Smith and is characteristic of the species. 



Distribution: Southern Great Plains; sporadic in sloughs, swamps, and ponds. 

 Collections examined from Kansas, Missouri, Oklahoma. (FIG. 12.) 



A not too common plant most closely related to 5". papulosa, differing from 

 that species in its larger, winged-faced achenes and its remotely papillose, 

 elongate bracts. The two species have distinct and separate ranges which ap- 

 proach each other but apparently never overlap. No intermediate forms have been 

 seen, although they are to be expected. If such intermediates do exist, there may 

 be reasonable justification for reducing S. ambigua to a subspecies of S. papulosa. 



14. Sagittaria macrophylla Zucc. Ahb. Bayr. Acad. 1: 289. 1832. 

 Sagittaria mexicana Steud. Nom. ed. 2. 2: 491. 1841. 



Perennial with short, small rhizome and elongate runners. Leaves emersed 

 with lanceolate to ovate blades 8-20 x 1.5-7 cm, frequently with 1 or 2 basal 

 lobes to 8 cm long and 2 cm wide. Scape simple with 2-5 distant whorls of 

 flowers. Bracts 1-2 cm long, at first strongly connate and membranous, at length 

 nearly free and thickish. Pistillate flowers with thickish, recurved pedicels (as- 

 cending in youth) 4-15 cm long; sepals more or less reflexed, 0.7-1 cm long; 

 petals ca. twice as long; stamens frequently present, non- functional, in a ring. 

 Staminate flowers with 18-<» stamens, the glabrous, gradually tapering filaments 

 2.5-3.3 mm long, the oblong anthers 1.8-2.1 mm long. Mature receptacle 1-1.3 cm 

 in diameter; achenes obovate, 2.8-3.1x2-2.5 mm, the dorsal wing ca. 0.6 mm 

 wide, somewhat wider than the ventral wing, the erect, subapical, thick-based 

 beak 0.3-0.7 mm long, variously curved. (FIG. 9b-d.) 



Type collection: Karwinski s.n., Mexico (holotype, not seen, presumably at 

 Munich; frag, of holotype MO). 



Distribution: Mexico; apparently limited to the region around Mexico City, 

 there, on the basis of the numerous collections, locally abundant in lakes and 

 ponds. (FIG. 9.) 



A peculiar species of extremely limited range, S. macrophylla is unique in 

 several respects. It is apparently related to the sagittate-leaved members of the 

 subgenus Sagittaria and at the same time shows unmistakable affinities with the 

 subgenus Lophotocarpus. It resembles 5. latifolia and its allies in the more or 

 less reflexed sepals, glabrous filaments, and sagittate leaves. The thickened, 

 recurved pistillate pedicels and general bract characteristics are close to those 

 of 5. montevidensis. The remarkable length of the pistillate pedicels is unique, 

 as are the characters of the achenes. The fact that the pistillate flower frequently 

 bears a ring of non-functional stamens leads the writer to believe that the species 

 is intermediate between the two subgenera. 



