Plants perennial, rarely annual, submersed, floating-leaved, or emersed, glabrous to sparsely pubescent; rhizomes often present, occasionally terminated by tubers; stolons often present; corms absent; tubers white to brown, smooth. Roots septate. Leaves sessile or petiolate; petiole terete to triangular; blade with translucent markings absent, linear to obovate, base attenuate to hastate or sagittate, margins entire, apex round to acute. Inflorescences racemes, panicles, rarely umbels, of 1–17 whorls, erect, emersed or floating, rarely submersed; bracts coarse or delicate, apex obtuse to acute, smooth or papillose proximally to distally. Flowers unisexual, the proximal rarely with ring of sterile stamens; staminate flowers pedicellate, distal to pistillate flowers; pistillate flowers mostly pedicellate, rarely sessile; bracts subtending pedicels, lanceolate, shorter than pedicels, apex obtuse to acute; pedicels ascending to recurved; receptacle convex; sepals recurved in staminate flowers, recurved to erect in pistillate flowers, often sculptured, herbaceous to leathery; petals white, rarely with pink spot or tinge, entire; stamens 7–30; filaments linear to dilated, glabrous to pubescent; pistils to 1500 or more, spirally arranged, not radiating in starlike pattern, distinct; ovules 1; styles terminal. Fruits without longitudinal ribs, compressed, abaxially keeled or not, abaxial wings often present, lateral wing often present, 1, curved, glands present. x = 11.

Distribution

Mostly Western Hemisphere, Europe, Asia.

Discussion

Species ca. 30 (24 in the flora).

Selected References

Beal, E. O., J. W. Wooten, and R. B. Kaul. 1982. Review of Sagittaria engelmanniana complex (Alismataceae) with environmental correlations. Syst. Bot. 7: 417--432.

Bogin, C. 1955. Revision of the genus Sagittaria (Alismataceae). Mem. New York Bot. Gard. 9: 179--233.

Rataj, K. 1972. Revision of the genus Sagittaria. Part II. (The species of West Indies, Central and South America). Annot. Zool. Bot. 78.

Wooten, J. W. 1973. Taxonomy of seven species of Sagittaria from eastern North America. Brittonia 24: 64--74.

Lower Taxa

Sagittaria ambigua, Sagittaria australis, Sagittaria brevirostra, Sagittaria cristata, Sagittaria cuneata, Sagittaria demersa, Sagittaria engelmanniana, Sagittaria fasciculata, Sagittaria filiformis, Sagittaria graminea, Sagittaria guayanensis, Sagittaria isoetiformis, Sagittaria kurziana, Sagittaria lancifolia, Sagittaria latifolia, Sagittaria longiloba, Sagittaria montevidensis, Sagittaria papillosa, Sagittaria platyphylla, Sagittaria rigida, Sagittaria sanfordii, Sagittaria secundifolia, Sagittaria subulata, Sagittaria teres

Key

1	Fruiting pedicels recurved or rarely spreading; pistillate sepals mostly erect and closely enclosing flower or fruiting head, occasionally spreading to recurved.	> 2
1	Fruiting pedicels spreading to ascending or absent; pistillate sepals mostly spreading to recurved, not enclosing flower.	> 9
2	Leaves, at least some, emersed.	> 3
2	Leaves submersed, floating, rarely emersed, or plants stranded on shore.	> 5
3	Fruiting heads 1.2–2.1 cm diam.; leaf blade hastate to sagittate	Sagittaria montevidensis
3	Fruiting heads 0.7–1.2 cm diam.; leaf blade linear-ovate to lance-elliptic.	> 4
4	Achenes abaxially keeled, mostly more than 2 mm; faces not tuberculate, often with glands; California.	Sagittaria sanfordii
4	Achenes not abaxially keeled, mostly less than 2 mm, faces tuberculate, without glands; e of Rocky Mountains.	Sagittaria platyphylla
5	Achene faces tuberculate; floating leaves with sagittate blades present at least on some plants of population.	Sagittaria guayanensis
5	Achene faces not tuberculate; floating leaves absent or, if present, with unlobed or hastate blades.	> 6
6	Fruiting pedicels 0.2–1.1 cm; phyllodia lenticular in cross section; tidal muds; mostly brackish waters.	Sagittaria subulata
6	Fruiting pedicels 1.5–6.5 cm; phyllodia flattened in cross section; rarely tidal muds; mostly fresh waters.	> 7
7	Leaves with blades and petioles usually present on some plants; some plants often stranded along shore, these usually with expanded leaf blades.	Sagittaria filiformis
7	Leaves all phyllodia; plants almost always submersed, rarely stranded, these without expanded leaf blades.	> 8
8	Phyllodia 50–250 cm; Florida springs.	Sagittaria kurziana
8	Phyllodia 12–53 cm; streams and lakes, New Mexico.	Sagittaria demersa
9	Filaments pubescent to tomentulose (except S. fasciculata).	> 10
9	Filaments glabrous.	> 17
10	Leaves all phyllodia, nearly terete; ne United States.	Sagittaria teres
10	Leaves with blades and petioles or if phyllodia, then flattened to triangular in cross section; mostly widespread.	> 11
11	Pistillate flowers sessile to subsessile.	Sagittaria rigida
11	Pistillate flowers obviously pedicellate.	> 12
12	Filaments cylindric.	Sagittaria lancifolia
12	Filaments dilated.	> 13
13	Rhizomes present, coarse; stolons and corms absent.	> 14
13	Rhizomes absent or if present, then not coarse; corms and/or stolons present.	> 15
14	Abaxial wing of fruit ± entire; plants widespread	Sagittaria graminea
14	Abaxial wing of fruit scalloped or toothed; ne Alabama	Sagittaria secundifolia
15	Filaments exceeding anthers in length.	Sagittaria cristata
15	Filaments shorter than or equaling anthers in length.	> 16
16	Blades of emersed leaves 0.5 cm or more wide; w Carolinas.	Sagittaria fasciculata
16	Blades of emersed leaves, if present, 0.4(–0.5) cm or less wide; se coastal plain.	Sagittaria isoetiformis
17	Emersed leaf blades linear to ovate.	> 18
17	Emersed leaf blades cordate, sagittate, or hastate.	> 20
18	Bracts papillose.	Sagittaria papillosa
18	Bracts not papillose.	> 19
19	Emersed plants with erect to ascending petioles; leaf blades lanceolate to ovate.	Sagittaria ambigua
19	Emersed plants with recurved petioles; leaf blades linear to sagittate.	Sagittaria cuneata
20	Bracts distinct or connate much less than ¼ total length.	> 21
20	Bracts connate at least ¼ total length.	> 23
21	Flowers in 2–4 whorls; achenes with facial glands.	Sagittaria engelmanniana
21	Flowers in 5–12 whorls; achenes without facial glands.	> 22
22	Petiole winged in cross section; achene beak strongly recurved.	Sagittaria australis
22	Petiole ridged in cross section; achene beak ascending apically.	Sagittaria brevirostra
23	Achene beak 1–2 mm, horizontal.	Sagittaria latifolia
23	Achene beak 0.1–0.6 mm, erect or incurved.	> 24
24	Emersed plants with recurved petioles and linear to sagittate blades; basal lobes equal to or shorter than remainder of blade; submersed leaves phyllodial, floating leaves cordate to sagittate	Sagittaria cuneata
24	Emersed plants with ascending to erect petioles and sagittate blades; basal lobes longer than remainder of blade; submersed and floating leaves absent.	Sagittaria longiloba