Arrowhead (Sagittaria)

Group I. sep appressed in fr; lower fls perfect; fruiting pedicels recurved

tidal a.h. (2. spatula) brackish to nearly fresh tidal waters & salt marshes; s to NC

Group II & III. sepal reflex in fr; lower fls pistillate: fruiting pedicels in most spp. more or less ascending

Group II. filaments smooth, without scales; lvs often sagittate

..... most or all lv arrow-shaped; long petioled:   rarely arrow-shaped    
..... lanceolate or phyllodial sometimes narrow sagittate deltoid-ovate phyllodial & bladless
4)stamens mostly 7-15 ..... ..... ..... ..... tidal a.h. (2.spatula) brackish to nearly fresh tidal waters & salt marshes; s to NC
4) stamens 15-many ..... ..... ..... ..... .....
5) beak of the achene spreading at right angles to the body; bract more or less boat-shaped 1-1.5 " ..... ..... ..... ..... common a.h. (8.latifolia) varies from broad to narrow arrow- shaped; abundant in swamps, ponds, & streams; s to trop Am
5)beak of achene ascending to erect (or distally incurved); bracts not boat-shaped ..... ..... ..... ..... .....
6) beak of achene erect, short, to 0.5mm; achene nearly or quite without facial wings northern a.h. (7.cuneata) ponds & marshes in water or mud (often sandy silt) s to NY ..... ..... ..... .....
6) beak ascending, more than 0.5mm; achenes us. w/ one or more facial wings ..... ..... ..... ..... .....
7) fls in 2-4 whorls; bracts relatively thick & herbaceous; near the coast; 2/3-1" ..... ..... Englemann's a.h. (4.engelmanniana) narrowly arrow- shaped; acid waters of bogs, ponds & streams near the coast from MA to FL ..... .....
7) fls in 5-12 whorls; bracts stramineous, firm and papery; mostly inland ..... ..... Appalachian a.h. (5.australis) circumneutral water of lakes, ponds, or swamps; NY to GA ..... .....

Group III. filaments roughened with minute scales; lvs only rarely sagittate

..... round lvs flat-blade lance-shaped to oval
10)pistillate fls sessile or nearly so; scape often bent at the lowest fl-whorl 1/2-3/4" ..... ..... sessile-fruited a.h. (10.rigida) in shallow water of swamps & ponds; ME to VA
10) pistillate fls evid. pedicellate; scape not bent ..... ..... .....
11) phyllodia flat, not nodose; widespread; 1/2" wide ..... grass-leaved a.h. (11.graminea) swamps, mud, & shallow water; s to Cuba .....
11)phyllodia terete, nodose: 1/2" wide slender a.h. (12.teres) on sandy soil in shallow, acid water from MA to NJ ..... .....