Flora of North America species comparison

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Sagittaria filiformis

narrow-leaf arrowhead, threadleaf arrowhead
Habit Herbs, perennial, to 170 cm, mostly of fresh waters, some plants stranded along shore; rhizomes absent; stolons present; corms present.
Leaves

submersed or floating, rarely emersed; submersed phyllodial, flattened, 30–250 × 0.1–1.5 cm; floating with petiole flattened, to 40 cm, blade linear-ovate to ovate, rarely sagittate, to 3.5 × 0.5 cm; emersed with petiole 5–10 cm, blade linear-ovate to ovate, rarely hastate to sagittate, to 4 × 0.5 cm; stranded plants usually with expanded leaf blades.
Inflorescences

racemes, rarely panicles, of 4–10 whorls, floating to slightly emersed, 15–25 × 5–15 cm;

peduncles 10–200 cm;

bracts connate more than ¼ total length, lanceolate, 110 mm, delicate, not papillose; fruiting pedicels spreading to recurved, cylindric, 1.5–4.5 cm.
Flowers

to 3 cm diam.;

sepals spreading in staminate, erect in pistillate, enclosing flower or fruiting head;

filaments dilated, ± equaling anthers, glabrous;

pistillate pedicellate, without ring of sterile stamens.
Fruiting

heads 0.7–1 cm diam.;

achenes obovoid, abaxially keeled, 5 × 2.5 mm, beaked;

faces not tuberculate, wings 0–3, ± entire, glands 0–1;

beak lateral, erect, 1 mm.
2n

= 22.

Sagittaria filiformis
Phenology Flowering summer–fall.
Habitat Shallow, swift waters or deep streams in northern portion of range, ponds, lakes, drainage canals, and swamps in southern portion of range
Elevation 0–100 m (0–300 ft)
Distribution
from FNA
AL; CT; FL; GA; MA; ME; NC; NJ; NY; PA; RI; SC; VA
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 22.
Parent taxa Alismataceae > Sagittaria
Sibling taxa
S. ambigua, S. australis, S. brevirostra, S. cristata, S. cuneata, S. demersa, S. engelmanniana, S. fasciculata, S. graminea, S. guayanensis, S. isoetiformis, S. kurziana, S. lancifolia, S. latifolia, S. longiloba, S. montevidensis, S. papillosa, S. platyphylla, S. rigida, S. sanfordii, S. secundifolia, S. subulata, S. teres
Synonyms S. stagnorum, S. subulata var. gracillima
Name authority J. G. Smith: N. Amer. Sagittaria. 20, plate 15, figs. 5–8. (1894)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Apiaceae, Boraginaceae, and Polemoniaceae.)

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