Sagittaria teres S. Watson

Herbs, perennial, to 80 cm; rhizomes absent; stolons present; corms present. Leaves emersed or submersed, sessile, phyllodial, nearly terete; emersed, to 60 ´ 0.15--0.7 cm; submersed, 3.5--18.5 ´ 0.15--0.4 cm. Inflorescences racemes, of 1--4 whorls, emersed, 2.5--4 ´ 2.5--6 cm; peduncles 10--80 cm; bracts connate more than or equal to total length, subulate, 2--3 mm, delicate, not papillose; fruiting pedicels obliquely ascending, filiform, 1 cm. Flowers to 1.5 cm diam.; sepals recurved, not enclosing flower; filaments dilated, ± equaling anthers, pubescent; pistillate pedicellate, without ring of sterile stamens. Fruiting heads 0.6--1 cm diam.; achenes obovoid-cuneate, abaxially keeled, 2--3 ´ 1.2--1.5 mm, beaked; faces not tuberculate, wings absent, glands 1--2; beak erect to horizontal, 0.3--0.4 mm. 2n = 22.

Mass., N.J., N.Y., R.I.

Flowering summer (Jul--Sep).

Sandy pond shores and swamps of acid waters, mainly along Atlantic Coastal Plain; 0--100m.

Sagittaria teres S. Wats, in A. Gray, Man. ed. 6. 555. 1890
Plants more or less submerged, 1.5-6.5 dm. tall ; leaves usually represented by elongate, attenuate, nodose phyllodia, 10-60 cm. long, occasionally developing narrow imperfect blades ; scapes slender, 1-6, dm. tall, longer than the leaves ; bracts ovate, 3 mm. long, obtuse ; whorls of the inflorescence solitary or sometimes 3, 1 or 2 pedicels of the lower whorl bearing pistillate flowers, 10-25 mm. long, longer than those of staminate flowers ; sepals ovate or oval, becoming 3 mm. long; corolla 12-15 mm. broad; filaments dilated, pubescent, shorter than the anthers; anthers oblong; fruit-heads 8-12 mm. in diameter; achenes oval or oval-obovate, 2 mm. long, with the dorsal margin undulate and the ventral one nearly straight, the several facial wings undulate, the beak stout, near the top of the achene-body, curved upward.
Type locality : Massachusetts.
Distribution : Massachusetts to South Carolina.

Sagittaria teres, the quill-leaved arrowhead or slender arrowhead, is an aquatic plant species in the genus Sagittaria native to the northeastern United States: Rhode Island (Providence and Washington Counties), Massachusetts, New Hampshire (Hillsborough County), New York (Suffolk County) and New Jersey.

Sagittaria teres grows along the shores of lakes, marshes, and other wetlands, frequently those with acidic water such as Sphagnum bogs.

Sagittaria teres is a perennial herb up to 80 cm (32 inches) tall. Leaves can grow both under the water and above it. Flowers are white, up to 1.5 cm (0.6 inches) in diameter, borne in one or more whorls on a stalk rising above the leaves.

Sagittaria teres là một loài thực vật có hoa trong họ Alismataceae. Loài này được S.Watson miêu tả khoa học đầu tiên năm 1890.