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



garded as having some of the longest recorded angiosperm leaves. The remarkably 

 elo ngate inflorescence must also be regarded as approaching a record length. 

 This taxon needs further study to determine the causes of this great size. The 

 answer probably should be sought in its ecology and cytology. 



S. subulata, with recurved and variously thickened pistillate pedicels and 

 widely spreading (but not reflexed) sepals, is most closely related to S. demersa 

 and S. montevidensis . It probably represents the end-line in development in the 

 subgenus Lophotocarpus . The point of origin of the subgenus Sagittaria, marked 

 by its reflexed sepals, in uncertain. 



Subgenus 2. Sagittaria. 



Sagitta Adans. Fam. PI. 2: 459. 1763. 

 Diphorea Raf. Noegen. 3. 1825. 

 Drepacbnia Raf. Neogen. 3. 1825. 



Sagittaria sect. Eusagittaria Benth. & Hook. Gen. PI. 3(2): 1006. 1883. 



Mature pistillate flowers with reflexed sepals, their pedicels mostly ascend- 

 ing, if recurved, not markedly thickened. Perfect flowers rarely present. (Species 

 9-20.) 



9. Sagittaria rigida Pursh, Fl. Am. Sept. 2: 397. 1814. 



Sagittaria bulbosa Donn, Hort. Cant. ed. 6. 246. 1811. Nomen nudum. 

 Sagittaria heterophylla Pursh, Fl. Am. Sept. 2: 397. 1814. 

 Sagittaria sagitti folia var. minor Hook. Fl. Bor. Am. 2: 167, p.p. 1840. 

 Sagittaria sagittifolia var. rigida (Pursh) Torr. Nat. Hist. N.Y. 2(2): 259. 1843. 

 Sagittaria heterophylla var. fluitans Engelm. in A. Gray, Man. Bot. ed. 2. 439. 1856. 

 Sagittaria heterophylla var. angusti folia Engelm. in A. Gray Man. Bot. ed. 5. 494. 1867. 

 Sagittaria heterophylla var. elliptica Engelm. in A. Gray, Man. Bot. ed. 5. 494. 1867. 

 Sagittaria heterophylla var. rigida (Pursh) Engelm. in A. Gray, Man. Bot. ed. 5. 494. 1867. 

 Sagittaria rigida var. engelmanniana Farw. Ann. Rep. Comm. Parks Detroit 44. 1900. 

 Sagitta rigida (Pursh) Nieuwl. Am. Midi. Nat. 3: 22. 1913. 



Perennial with runners. Emersed or submerged. Emersed. leaves with linear 

 to elliptical blades 5-15x0.6-12 cm, occasionally with one or two linear re- 

 curving or divergent lobes, the submerged leaves modified into phyllodia 30-70 

 cm long or longer, the occasional floating ends rarely widened into a linear to 

 lanceolate blade; petioles 15-105 cm long. Scapes 10-115 cm long or longer, 

 simple, with 2-6 whorls of flowers, typically geniculate at the lowest whorl. 

 Bracts connate, 0.4-0.6 cm long, obtuse. Pistillate flowers sessile or subsessile, 

 rarely with ascending pedicels to 2.5 cm long; sepals 0.4-0.7 cm long, reflexed 

 at maturity; petals white, ca. twice as long as the sepals. Staminate flowers with 

 ascending pedicels 1-3 cm long; stamens 15-°S the pubescent filaments 1-2 mm 

 long, widened at the base, gradually tapering above, the ovate anthers 0.6-1.2 

 mm long. Mature pistillate heads echinate, 1-1.7 cm in diameter; achenes obovate 

 to oblong, 2-3 X 1.3-1.6 mm, the narrow wings 0.1«=0.3 mm wide, the faces typi- 

 cally with a long resin duct (this occasionally reduced or absent), the stoutish 

 recurved beak 0.8-1.4 mm long, obliquely or vertically inserted. (FIG. 13a-c.) 



Type collection: Pursh s.n., Canada (lectotype, NY). A search of the herbar- 

 ium at the Academy of Natural Sciences in Philadelphia failed to uncover either 

 of the plants Pursh described as S, rigida and S. heterophylla, and they are pre- 

 sumed to be lost. The only P«ursh collection at hand of this species is the plant 

 chosen as the lectotype. The specimen is quite small and very juvenile, but can 

 readily be identified by the long recurving beak of the immature achene, the sub- 

 sessile pistillate flower, and the pubescent filaments somewhat longer than the 

 anthers. 



