2955] 



REVISION OF THE GENUS SAGITTARIA 



223 



his name are larger throughout, since the key characteristics of bract-size, blade 

 and basal lobe ratios, and achene-differences show no geographical correlation and 

 intermediates are commonly found throughout the entire range. 



17. Sagittaria engelmanniana J.G.Sm. Mem. Torrey Club 5: 25. 1894. 



Perennial with rhizomes and/ or runners with corms. Leaves emersed, occa- 

 sionally linear to lanceolate, typically sagittate with linear to ovate attenuate or 

 obtuse blades 4.5-20 x 0.2-12 cm, the linear to ovate deltoid or attenuate basal 

 lobes 4-18 x 0.1-8 cm, the petioles 10-60 cm long. Scape 20-80 cm long or longer, 

 with 2-12 whorls of flowers, occasionally branching at the lowest whorl. Bracts 

 distinct, 0.5-3 cm long or longer, linear to lance-attenuate, firm or membranous. 

 Pedicels ascending, 0.7-3.5 cm long. Sepals 0.4-0.7 cm long, reflexed. Petals 

 white, nearly twice as long as the sepals. Stamens numerous, the slender glabrous 

 filaments 1-2.7 mm long, the oblong anthers 1-2 mm long. Mature receptacle 1-2.5 

 cm in diameter, often markedly echinate; achenes obovate or cuneate-obovate, 

 2.3-4 x 1.6-3 mm, the broad dorsal wing 0.4-1 mm wide, often crested, the ventral 

 wing 0.3-0.6 mm wide, the faces 0->winged, the erect or recurving obliquely to 

 apically inserted broad-based beak 0.5-2 mm long. 



1. Mature receptacle markedly echinate; scape typically simple. 



2. Bracts shorter than the pedicels; scape 2-4-whorled; bog plant of 



coastal regions. 17a. subsp. engelmanniana. 



2. Bracts equal to or exceeding the pedicels; scape more than 4-whorled; 



inland and southern plant. 17b. subsp. longirostra. 



1. Mature receptacle not echinate; scape often branched; northern and 



western plant. 17c. subsp. brevirostra. 



17a. Sagittaria engelmanniana subsp. engelmanniana 



Sagittaria variabilis var. gracilis S. Wats, in A. Gray, Man. Bot. ed. 6. 555, p.p. 1889. 

 Sagitta engelmanniana (J.G.Sm.) Nieuwl. Am. Midi. Nat. 3: 22. 1913. 



Leaves emersed, occasionally linear or lanceolate, typically sagittate, with 

 linear or lance-attenuate, rarely elliptical blades 4.5-10x0.2-2 cm, the basal 

 lobes linear to lance-attenuate. Scapes with 2-4 whorls of flowers. Bracts more 

 or less membranous, 0.5-1.2 cm long. Pedicels 1.5-3.5 cm long. Receptacle 

 echinate, 1-1.8 cm thick; achenes cuneate-obovate, 2.5-4 x 1.5-3 mm, the faces 

 1-3-winged, the obliquely ascending beak (0.7-)l-2 mm long. (FIG. 18a-c.) 



Type collection: September 1864, Robbins s.n., sphagnum bog, Uxbridge, 

 Worcester Co., Massachusetts (holotype MO; isotype GH). 



Distribution: Massachusetts to New Jersey, sporadic along the coast to South 

 Carolina; common especially northward in bogs and acid waters of ponds and 

 streams, Collections examined from Connecticut, Dealware, Maryland, Massa- 

 chusetts, New Jersey, New York, Rhode Island, South Carolina, Virginia. 

 (FIG. 18.) 



17b. Sagittaria engelmanniana subsp. longirostra (Micheli) Bogin, comb. nov. 



Sagittaria sagittifolia var. longirostra Micheli in DC. Monogr. Phan. 3: 69. 1881. 



Sagittaria longirostra (Micheli) J.G.Sm. Mem. Torrey Club 5: 26. 1894. 



Sagittaria variabilis var. echinocephala Engelm. ex J.G.Sm. Missouri Bot. Gard. Rep. 



6: 16. 1894. Nomen nudum. 

 Sagittaria longirostra var. australis J.G.Sm. in Mohr, Bull. Torrey Club 24: 20. 1897. 

 Sagittaria australis (J.G.Sm.) Small, Fl. SE. U.S. 46. 1903. 



Leaves sagittate, with ovate-deltoid obtuse blades 3-13x2.5-10 cm, the 

 basal lobes broad. Scape with 5-12 whorls of flowers. Bracts firm, 0.7-2.5 cm 

 long. Pedicels 0.7-2.3 cm long. Receptacle 1-1.5 cm thick, echinate; achenes 



